AC 91-67A

“DRAFT”

U.S. Department

of Transportation

Federal Aviation

Administration

Advisory

Circular

Subject: Minimum Equipment Requirements

for General Aviation Operations

Under 14 CFR Part 91, § 91.213

Date: DRAFT AC No: AC 91-67A

Initiated by: AFS-800 Change:

This advisory circular (AC) describes acceptable methods for the operation of aircraft with

certain inoperative instruments and equipment items, which are not essential for safe operations

under Title 14 of the Code of Federal Regulations (14 CFR) part 91, 133, or 137 (including

part 91 operations conducted by parts 141 and 142 certificate holders (CH)).

The contents of this document do not have the force and effect of law and are not meant to bind

the public in any way, and the document is intended only to provide information to the public

regarding existing requirements under the law or agency policies.

This AC describes an acceptable means, but not the only means, to operate an aircraft with

certain inoperative instruments and equipment items that are not essential. While using the

means described in this AC is not mandatory, an operator that voluntarily elects to use the means

described in this AC must follow, in all respects, the terms, conditions, and processes provided in

the AC.

Lawrence Fields

Acting Executive Director, Flight Standards Service

DATE “DRAFT” AC 91-67A

CONTENTS

Paragraph Page

Chapter 1. Introduction ................................................................................................................ 1-1

1.1 Purpose of This Advisory Circular (AC) ...................................................................... 1-1

1.2 Audience ....................................................................................................................... 1-1

1.3 Where You Can Find This AC...................................................................................... 1-1

1.4 What This AC Cancels.................................................................................................. 1-1

1.5 Related 14 CFR Sections .............................................................................................. 1-2

1.6 Related Documents (current editions) .......................................................................... 1-2

1.7 Background ................................................................................................................... 1-2

1.8 Definitions and Terminology ........................................................................................ 1-3

1.9 AC Feedback Form ....................................................................................................... 1-8

Chapter 2. Master Minimum Equipment List (MMEL) .............................................................. 2-1

2.1 General ......................................................................................................................... 2-1

2.2 ATA/JASC Coded System Section Components ......................................................... 2-1

2.3 Obtaining a Current MMEL.......................................................................................... 2-3

2.4 Aircraft for Which No MMEL Has Been Developed ................................................... 2-3

2.5 MMEL PLs ................................................................................................................... 2-3

2.6 MMEL PL Global Change (GC) Designation .............................................................. 2-4

Chapter 3. Minimum Equipment List (MEL) .............................................................................. 3-1

3.1 General ......................................................................................................................... 3-1

3.2 Three Methods for Operating an Aircraft with Inoperative Equipment ....................... 3-2

3.3 MEL LOA ..................................................................................................................... 3-2

3.4 Aircraft Operated Under Multiple 14 CFR Parts .......................................................... 3-3

3.5 Fleet MEL ..................................................................................................................... 3-3

Chapter 4. Conducting Operations Without an MEL .................................................................. 4-1

4.1 Operating Without an MEL .......................................................................................... 4-1

4.2 Removal, Deactivation, and Placarding ........................................................................ 4-1

4.3 Continued Operation with Inoperative Items ................................................................ 4-2

4.4 Safety Risk Analysis of Proposed Operation with Inoperative Equipment Items ........ 4-3

DATE “DRAFT” AC 91-67A

iii

Chapter 5. Conducting Operations with an MEL ........................................................................ 5-1

5.1 Operating with an MEL ................................................................................................ 5-1

5.2 Documentation of Deferred Items ................................................................................ 5-2

5.3 Placarding ..................................................................................................................... 5-2

5.4 Performing (M) and (O) Procedures ............................................................................. 5-2

5.5 Repair of Deferred Instruments or Equipment Items .................................................... 5-3

Chapter 6. Application for MEL Letter of Authorization (LOA) ................................................ 6-1

6.1 Application for an MEL Approval Issued Under LOA D095 ...................................... 6-1

6.2 Application for an MEL Approval Issued Under LOA D195 ...................................... 6-1

6.3 Request for Approval of an MEL That Does Not Conform to This AC....................... 6-1

6.4 Oversight ....................................................................................................................... 6-1

Chapter 7. Content of a Procedures Document ............................................................................ 7-1

7.1 MEL Approval Under LOA D095 ................................................................................ 7-1

7.2 Procedures Document Content ..................................................................................... 7-1

7.3 Procedures Document Required Sections ..................................................................... 7-1

7.4 Procedures Document Optional Sections...................................................................... 7-3

7.5 Example “As Required by 14 CFR” and (M) and (O) Procedures ............................... 7-3

Chapter 8. Content of an Operator-Developed MEL ................................................................... 8-1

8.1 MEL Approval Under LOA D195 ................................................................................ 8-1

8.2 MEL Content ................................................................................................................ 8-1

8.3 MEL Required Sections ................................................................................................ 8-1

8.4 MEL Optional Sections................................................................................................. 8-2

8.5 ATA/JASC Coded System Sections ............................................................................. 8-2

8.6 Example Proviso, “As Required by 14 CFR,” and (M) and (O) Procedures ................ 8-7

Chapter 9. MEL Revisions ........................................................................................................... 9-1

9.1 General ......................................................................................................................... 9-1

9.2 FAA-Initiated MEL Revisions ...................................................................................... 9-1

9.3 Operator-Initiated MEL Revisions ............................................................................... 9-4

9.4 Vertical Bar (Change Bar) ............................................................................................ 9-4

Chapter 10. MEL Relief for Items Installed After Type Certification ....................................... 10-1

10.1 General ...................................................................................................................... 10-1

DATE “DRAFT” AC 91-67A

10.2 Operator NEF Items or Administrative Control Items (ACI) ................................... 10-1

10.3 MMEL Items and MEL Items ................................................................................... 10-1

10.4 MMEL PL-109 .......................................................................................................... 10-1

10.5 STCs ....................................................................................................................... 10-1

10.6 Adding Relief for Items Installed After Type Certification ...................................... 10-2

10.7 Items Needed for Evaluation of Design Changes ..................................................... 10-3

Chapter 11. Nonessential Equipment and Furnishings (NEF) Program .................................... 11-1

11.1 Definition................................................................................................................... 11-1

11.2 Background ............................................................................................................... 11-1

11.3 The NEF Program Under § 91.213(a) ....................................................................... 11-1

11.4 Deferral Authority ..................................................................................................... 11-2

11.5 NEF Program Development ...................................................................................... 11-3

11.6 Required NEF Program Contents .............................................................................. 11-3

11.7 NEF Program Approval............................................................................................. 11-4

11.8 Criteria for Selection of NEF Items .......................................................................... 11-4

11.9 NEF Deferral Process ................................................................................................ 11-5

Chapter 12. Configuration Deviation List (CDL) ...................................................................... 12-1

12.1 Purpose of the CDL ................................................................................................... 12-1

12.2 Development ............................................................................................................. 12-1

12.3 CDL Versus MEL ..................................................................................................... 12-1

12.4 CDL Management Program ...................................................................................... 12-2

List of Figures

Figure 2-1. Example MMEL ATA/JASC Coded System Section Page .................................... 2-2

Figure 2-2. Sample Global Change Header Box ....................................................................... 2-4

Figure 4-1. PIC Decision Sequence ........................................................................................... 4-4

Figure 5-1. PIC Decision Sequence ........................................................................................... 5-4

Figure 6-1. Sample LOA D095 Request Letter ......................................................................... 6-2

Figure 6-2. Sample LOA D195 Request Letter for an Operator-Developed MEL That Conforms

to the Content Described in AC 91-67 .................................................................... 6-3

Figure 6-3. Sample LOA D195 Request Letter for an Operator-Developed MEL That Does Not

Conform to the Content Described in AC 91-67 .................................................... 6-4

Figure 7-1(a). Example MMEL “As Required by 14 CFR” Statement ...................................... 7-3

DATE “DRAFT” AC 91-67A

Figure 7-1(b). Example Procedures Document “As Required by 14 CFR” Regulatory

Reference or Requirement/Limitation ................................................................. 7-4

Figure 7-2(a). Example 1 MMEL Maintenance (M) and Operations (O) Symbols and

Provisos ................................................................................................................ 7-4

Figure 7-2(b). Example 1 Procedures Document Maintenance (M) and Operations (O)

Procedures ............................................................................................................ 7-4

Figure 7-3(a). Example 2 MMEL Maintenance (M) Symbol and Proviso ................................. 7-5

Figure 7-3(b). Example 2 Procedures Document Maintenance (M) Procedure .......................... 7-5

Figure 8-1(a). Example MMEL General “As Required by 14 CFR” Statement ........................ 8-8

Figure 8-1(b). Example MEL Specific “As Required by 14 CFR” Regulatory Reference......... 8-8

Figure 8-1(c). Example MEL Specific “As Required by 14 CFR” Requirement/Limitation ..... 8-9

Figure 8-2(a). Example 1 MMEL General Maintenance (M) and Operations (O) Symbols

and Provisos ......................................................................................................... 8-9

Figure 8-2(b). Example 1 MEL Specific Maintenance (M) and Operations (O) Symbols

and Provisos ....................................................................................................... 8-10

Figure 8-2(c). Example 1 Procedures Document Maintenance (M) and Operations (O)

Procedures .......................................................................................................... 8-10

Figure 8-3(a). Example 2 MMEL General Maintenance (M) Symbol and Proviso ................. 8-11

Figure 8-3(b). Example 2 MEL Specific Maintenance (M) Symbol and Proviso .................... 8-11

Figure 8-3(c). Example 2 Procedures Document Maintenance (M) Procedure ........................ 8-12

Figure 8-4(a). Example 3 MMEL General Operation (O) Symbol and Proviso ....................... 8-12

Figure 8-4(b). Example 3 MEL Specific Operations (O) Symbol and Proviso ........................ 8-12

Figure 8-4(c). Example 3 Procedures Document Operations (O) Procedure ............................ 8-13

Figure 11-1. Required NEF MEL Proviso for an Operator’s NEF Program .......................... 11-4

Figure 11-2. NEF Item Selection Criteria Elements Flowchart ............................................. 11-7

DATE “DRAFT” AC 91-67A

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CHAPTER 1. INTRODUCTION

1.1 Purpose of This Advisory Circular (AC). This AC describes acceptable ways in which

an aircraft can be operated under Title 14 of the Code of Federal Regulations (14 CFR)

part 91, 133, or 137 (including part 91 operations conducted by parts 141 and 142

certificate holders (CH)) with certain inoperative instruments and equipment items that

are not essential for safe operations, in accordance with part 91, § 91.213. The methods

described are not the only means to comply with § 91.213. The Federal Aviation

Administration (FAA) will consider other means of compliance an operator may present.

1.1.1 Effects of Guidance. The contents of this document do not have the force and effect of

law and are not meant to bind the public in any way, and the document is intended only

to provide information to the public regarding existing requirements under the law or

agency policies. While using the means of compliance described in this AC is not

mandatory, an operator that voluntarily elects to use the means of compliance described

in this AC must follow, in all respects, the terms, conditions, and processes described in

the AC. The use of terms such as “shall” and “must” throughout the AC do not impose

any regulatory requirement.

1.2 Audience. This AC applies only to aircraft operated under parts 91, 133, and 137

(including part 91 operations conducted by parts 141 and 142 CHs) with certain

inoperative instruments and equipment.

Note: Unless otherwise stated, the term “operator,” used throughout this AC,

applies to part 91 operators, parts 133 and 137 CHs, and part 141 pilot schools or

provisional pilot schools. This AC uses the singular term “operator” for

simplicity.

1.2.1 Applicability. This AC does not apply to part 91 subpart K (part 91K) program managers

or CHs under 14 CFR part 121, 125 (including part 125 Letter of Deviation Authority

(LODA) holders), or 135. These operators are required to comply with their approved

minimum equipment list (MEL), even when the operation is conducted under part 91.

Refer to § 91.213(c).

1.2.2 Foreign Air Carriers and Foreign Operators of U.S. Registered Aircraft Engaged in

Common Carriage (14 CFR Part 129). Foreign air carriers and foreign operators of U.S.

registered aircraft engaged in common carriage should refer to AC 129-4, Maintenance

Programs for U.S. Registered Aircraft Operated Under 14 CFR Part 129, for information

regarding their MELs.

1.3 Where You Can Find This AC. You can find this AC on the FAA’s website at

https://www.faa.gov/regulations_policies/advisory_circulars and the Dynamic Regulatory

System (DRS) at https://drs.faa.gov.

1.4 What This AC Cancels. AC 91-67, Minimum Equipment Requirements for General

Aviation Operations Under FAR Part 91, dated June 18, 1991, was canceled on

November 3, 2017.

DATE “DRAFT” AC 91-67A

1-2

1.5 Related 14 CFR Sections. All regulatory references in this AC are found in 14 CFR

unless otherwise indicated. The following 14 CFR sections are related to this AC. You

can download the full text of these regulations at the U.S. Government Publishing Office

(GPO) Electronic Code of Federal Regulations (e-CFR) website at https://ecfr.gov. You

can order a paper copy by sending a request to the U.S. Superintendent of Documents,

U.S. Government Publishing Office; by calling the telephone number 202-512-1800; or

by sending a request by facsimile at 202-512-2104.

• Part 21, §§ 21.19, 21.197, and 21.199.

• Part 43, §§ 43.3, 43.7, 43.9, 43.11, and 43.13.

• Part 91, §§ 91.7, 91.205, 91.213, 91.405, 91.417, and 91.501.

1.6 Related Documents (current editions).

• Master Minimum Equipment List (MMEL) Policy Letter (PL)-25, MMEL/MEL

Definitions.

• MMEL PL-36, 14 CFR Part 91 MEL Approval and Preamble.

• AC 43-9, Maintenance Records.

• AC 43-12, Preventive Maintenance.

• AC 91-70, Oceanic and Remote Continental Airspace Operations.

1.7 Background. The airworthiness certification of an aircraft is conditioned on the aircraft

conforming to its type certificate (TC) and being in a condition for safe operation. While

items installed in an aircraft must be operative for the aircraft to conform to its TC, an

approved MEL allows an operator to operate the aircraft with certain items inoperative.

An approved MEL, as authorized by a Letter of Authorization (LOA) under § 91.213(a),

constitutes an approved change to the type design without requiring recertification.

1.7.1 Airworthiness. Under § 91.7, an operator cannot operate an aircraft unless it is in an

airworthy condition. As noted above, to be airworthy, the aircraft must conform to its TC

and be in a condition for safe operation. An inoperative item present on the aircraft would

result in a violation of § 91.7, unless the inoperative item or equipment is listed on the

operator’s approved MEL, in accordance with § 91.213. As such, compliance with all

applicable criteria of an MEL is necessary when taking advantage of the relief an MEL

provides; in the absence of such compliance, the FAA would not consider the aircraft

airworthy.

1.7.2 Acceptable Level of Safety (ALoS). The FAA developed the concept of the MEL after

recognizing that under certain circumstances, a flight or series of flights might occur

safely with certain inoperable instruments and equipment. In certain specific situations,

an ALoS can be met because not all of an aircraft’s installed instruments and equipment

are necessary for every type of operation. For example, a flight that is not being

conducted in icing conditions would not require operable airframe deicing or anti-icing

equipment. Similarly, an aircraft that will not operate at night may receive relief from the

DATE “DRAFT” AC 91-67A

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requirement to have an operable landing light. In other words, the MEL requirements and

related processes are independent from an aircraft’s operating requirements and an MEL

cannot authorize a deviation from operating rules.

1.7.3 Requirement for Items to be Operative. All items related to the airworthiness of the

aircraft that are not included in an approved MEL are required to be operative in

accordance with the aircraft’s TC. An MEL does not include obviously required items,

such as wings, rudders, flaps, engines, landing gear, etc. An aircraft is not airworthy

when any item that is not included in the MEL is inoperative.

1.7.4 Repair Inoperative Items at Earliest Opportunity. The MEL is intended to permit

operations with inoperative items of equipment for the minimum period of time necessary

until repairs can be accomplished. It is important that repairs be accomplished at the

earliest opportunity to return the aircraft to its design level of safety and reliability.

1.7.5 MEL Development. The MEL is developed from an MMEL for the aircraft type. The

operator uses the MMEL as the baseline to develop the MEL and the operational and

maintenance procedures and lists the items installed in the operator’s aircraft. The MEL

is developed by the operator for their particular type of operation (i.e., instrument flight

rules (IFR), visual flight rules (VFR), Category (CAT) II, over water, etc.). The MEL is

approved by the responsible Flight Standards office.

1.8 Definitions and Terminology. For additional MMEL and MEL definitions, refer to

MMEL PL-25.

1.8.1 Airworthiness Directive (AD). ADs are legally enforceable regulations issued by the

FAA in accordance with 14 CFR part 39 to correct an unsafe condition in a product.

Part 39 defines a product as an aircraft, engine, propeller, or appliance.

1.8.2 Air Transport Association of America (ATA)/Joint Aircraft System/Component (JASC)

Coded System Section Components. MMEL system sections are organized by aircraft

system according to the ATA or JASC coded numbering system. MMEL system numbers

use the ATA/JASC codes that are standardized for each aircraft system. The ATA/JASC

numbering system provides an industrywide standard for numbering aircraft systems and

is relevant for all aircraft. ATA changed its name to Airlines for America (A4A) in 2011;

however, the acronym “ATA” is still used for coded aircraft systems. The acronyms

“ATA” and “A4A” are considered interchangeable. The alternate format for aircraft

system coding is the JASC codes, which are a modified version of the ATA codes.

1.8.3 Aircraft Evaluation Division (AED). The inspectors in AED serve as technical subject

matter experts for operational and engineering activities of the FAA’s Flight Standards

Service (FS). These inspectors coordinate and assist with aircraft certification and

continued airworthiness programs and serve as a liaison with the responsible Aircraft

Certification Service office during the initial certification of an aircraft and throughout

the service life of the aircraft.

1.8.4 Configuration Deviation List (CDL). A CDL is a list of externally exposed aircraft parts

that may be missing for flight. A CDL allows continued operation with missing

DATE “DRAFT” AC 91-67A

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externally exposed nonstructural parts by defining restrictions, limitations, or

performance penalties, while the aircraft remains airworthy. See Chapter 12 for

additional information on the CDL.

1.8.5 Deferral. The term “deferral” is used to describe the authorization for an operator to delay

repair and continue operating with a required item inoperative, under the authority of

their FAA-approved MEL. Authority to defer an inoperative item is subject to specific

conditions and limitations, as described in the associated proviso.

1.8.6 Dynamic Regulatory System (DRS). DRS is an FAA website that contains regulatory,

policy, and guidance information. DRS can be accessed at https://drs.faa.gov.

1.8.7 Flight Operations Evaluation Board (FOEB). An FOEB is comprised of technically

qualified specialists, engineering representatives, and aviation safety inspectors (ASI)

responsible for developing MMELs from the proposed MMEL provided by the aircraft

manufacturer. An aircraft MMEL is usually developed during initial aircraft certification.

FOEBs are also responsible for developing MMEL revisions. FOEBs coordinate with

internal and external stakeholders, such as the responsible Aircraft Certification Service

office, Flight Standards offices, aircraft and engine manufacturers, operators, and

private-sector groups.

1.8.8 Global Change (GC). A GC is newly developed or changed relief for an item, usually

applicable to numerous MMELs (hence “global”) to allow operators to obtain MEL relief

prior to the release of a revised MMEL. Incorporation of a GC into an operator’s MEL is

optional until the GC is incorporated in the aircraft’s MMEL. GCs may be used to

provide immediate relief for items required by a new regulatory requirement, policy

change, or new technology.

1.8.9 Kinds of Operations Equipment List (KOEL). Aircraft certificated under 14 CFR part 23

or 27 may have a KOEL. The KOEL specifies the kinds of operations (e.g., VFR, IFR,

day, or night) in which the aircraft can be operated. The KOEL also indicates the

installed equipment that may affect any operating limitation. Although the certification

rules require this information, there is no standard format; consequently, the

manufacturer may furnish it in various ways. Inoperative equipment, when required by

the KOEL for a particular type of operation (e.g., VFR, IFR, day, or night), may not be

deferred for that operation under § 91.213.

1.8.10 Letter of Authorization (LOA). The term “LOA,” used throughout this AC, refers to an

operator-specific LOA, which is the MEL-authorizing document containing conditions

and limitations the operator must comply with in order to conduct aircraft operations with

specific inoperative items. When used in this AC, the term “LOA” refers to all LOAs

issued under the provisions of § 91.213(a) to part 91 operators, part 133 rotorcraft

external-load operators, part 137 agricultural aircraft operators, and part 141 pilot schools

or provisional pilot schools.

Note: The part 142 training specification (TSpec) D095 has been

decommissioned. Part 142 training centers holding TSpec A003, Aircraft

DATE “DRAFT” AC 91-67A

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Authorization, and seeking MEL authorization must do so under the appropriate

operating rule (e.g., part 91, 121, or 135).

1.8.11 Maintenance (M) Procedure. The (M) symbol indicates a specific maintenance procedure

that must be accomplished prior to operation with the listed item inoperative. Normally,

(M) procedures are accomplished by qualified maintenance personnel; however, other

personnel may be qualified and authorized to perform certain functions. Procedures

requiring specialized knowledge or skill, or requiring the use of tools or test equipment,

should be accomplished by maintenance personnel. The satisfactory accomplishment of

all (M) procedures, regardless of who performs them, is the responsibility of the aircraft

operator. Appropriate procedures are required as a part of the aircraft operator’s MEL.

See paragraph 5.4, Performing (M) and (O) Procedures.

1.8.12 Master Minimum Equipment List (MMEL).

1.8.12.1 The term “MMEL,” used throughout this AC, means an FAA-approved,

aircraft make, model, and series (M/M/S)-specific master list of aircraft

instrument and equipment items that may be inoperative under certain

operational conditions, while maintaining the airworthiness of the aircraft and

providing an ALoS. An MMEL is the baseline document used by operators to

develop their own aircraft-specific MEL. Operators may download MMELs

from the “MMELs and AED Guidance Documents” section in DRS at

https://drs.faa.gov.

1.8.12.2 The United States may enter a Bilateral Aviation Safety Agreement (BASA)

with a foreign government when there is a need for technical cooperation with

the foreign government’s Civil Aviation Authority (CAA), and if the foreign

authority’s civil aviation safety oversight is substantially comparable to the

FAA’s. BASAs are carried out through associated implementation procedures.

Refer to country-specific BASAs for MMEL considerations relating to foreign

type-certificated aircraft validated under Implementation Procedures for

Airworthiness (IPA). The BASAs and associated IPAs may be found at

https://www.faa.gov/aircraft/air_cert/international/bilateral_agreements/.

1.8.13 Minimum Equipment List (MEL). The term “MEL,” used throughout this AC, means a

document listing items that may be inoperative during flight for a specific aircraft or a

fleet of aircraft. Operation of the aircraft under the MEL is authorized by an operator

specific LOA. As provided in § 91.213(a)(2), an MEL and the associated LOA constitute

a Supplemental Type Certificate (STC) for the aircraft. Operators will base their MEL on

the MMEL applicable to the aircraft M/M/S. An operator’s MEL may be more restrictive

than the MMEL, but it will not be less restrictive. Unless specified otherwise, the term

“MEL,” used throughout this AC, refers to both: (1) the MEL approval under LOA D095,

MMEL Used as an MEL, consisting of an MMEL and a procedures document, and (2)

the MEL approval under LOA D195, Minimum Equipment List (MEL), consisting of an

operator-developed MEL. When required for clarity, this AC will distinguish between an

MEL approval under LOA D095 or D195 by using the terms “procedures document,” or

“operator-developed MEL,” respectively.

DATE “DRAFT” AC 91-67A

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Note: MEL approvals under LOA D095 meet the International Civil Aviation

Organization (ICAO) MEL requirements of Annex 6, Parts II and III. However,

some CAAs may not accept LOA D095 as a valid MEL approval.

1.8.14 MMEL Policy Letters (PL). PLs clarify FAA MMEL policy regarding specific kinds of

equipment that may be deferred. While developing its MEL, an operator may need to

refer to one or more aircraft or equipment-specific PLs with a GC designation, as these

PLs may provide additional relief for items until the MMEL is revised. Operators may

download PLs from the “MMELs and AED Guidance Documents” section in DRS at

https://drs.faa.gov.

1.8.15 Make, Model, and Series (M/M/S). M/M/S is a common abbreviation used when

referring to a manufacturer’s particular model or type and series of given aircraft.

1.8.16 Nonessential Equipment and Furnishings (NEF) Program. An operator’s MEL program

may also include an NEF program that allows relief for nonessential items. An NEF

program allows operators to use the authority granted by their MEL LOA to provide

relief for nonessential items located throughout the aircraft. See Chapter 11 for additional

information on an NEF program.

1.8.17 Operational Control. As defined in 14 CFR part 1, § 1.1, operational control, “with

respect to a flight, means the exercise of authority over initiating, conducting or

terminating a flight.”

1.8.18 Operations (O) Procedure. The (O) symbol indicates a specific operations procedure that

must be accomplished prior to operation with the listed item inoperative. Normally, these

procedures are accomplished by the flightcrew; however, other personnel may be

qualified and authorized to perform certain functions. These procedures may be required

for flight planning purposes, or they may require action by the flightcrew. Additionally,

MEL items affecting the aircraft Weight and Balance (W&B) and cargo loading may

require procedures for additional personnel, such as those involved with aircraft load

control. The satisfactory accomplishment of all (O) procedures, regardless of who

performs them, is the responsibility of the aircraft operator. Appropriate procedures are

required as a part of the aircraft operator’s MEL. See paragraph 5.4.

1.8.19 Procedures Document. The procedures document is based on the MMEL applicable to

the aircraft M/M/S. The procedures document, the MMEL, and the MEL LOA D095

together constitute an approved MEL. The procedures document contains:

• The name(s) of the operator(s),

• The aircraft serial and registration numbers (or “Fleet”),

• The aircraft M/M/S,

• The MMEL revision number on which the MEL is based,

• (M) and (O) procedures that correspond with the (M) and (O) provisos listed in the

MMEL,

DATE “DRAFT” AC 91-67A

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• A list of all MMEL items that contain the statement “as required by 14 CFR,”

• All applicable definitions, per MMEL PL-25, and

• The preamble, per current MMEL PL-36.

1.8.20 Principal Base of Operations. The term “principal base of operations” used throughout

this AC is the physical address where an operator or pilot school conducts business or

resides. It is a physical location where the FAA can contact the operator (i.e., a post

office box is not an acceptable principal base of operations). While the principal base of

operations may coincide with the place where the aircraft is located, this is not always the

case. Depending upon the applicable 14 CFR part, this location may be an operator’s

residence, business address, home base of operations, or a pilot school’s principal

business office. For simplicity, this AC uses the singular term “principal base of

operations” to refer to all these locations.

1.8.21 Principal Inspector (PI). PIs are FAA personnel, within the operator’s responsible Flight

Standards office, who are assigned primary responsibility for oversight of an operator’s

safety of operations. PIs specialize in the three general areas of aircraft operations

according to their qualifications, either as a Principal Avionics Inspector (PAI), Principal

Maintenance Inspector (PMI), or Principal Operations Inspector (POI). PIs have FAA

administrative authority to evaluate and approve an operator’s manuals, including the

MEL.

1.8.22 Responsible Flight Standards Office. The term “responsible Flight Standards office,”

used throughout this AC, refers to the Flight Standards office responsible for issuance

and oversight of all LOAs for the operator. This is typically the Flight Standards office

with a Service Area (SA) covering the location of the operator’s principal base of

operations. FAA office locations are available at

https://www.faa.gov/about/office_org/field_offices/fsdo/ and

https://www.faa.gov/about/office_org/field_offices/ifo.

1.8.23 Responsible Person (Part 91 Only). The term “Responsible Person,” used throughout this

AC, is the person who has legal authority to sign the LOA on behalf of a part 91 operator.

Such person should have ongoing knowledge of the operations of the aircraft. The

Responsible Person may be the individual who acts as operator or, if the operator is a

legal entity, an officer, employee, or person duly designated to act on behalf of the

operator. The person assumes responsibility for ensuring the operator complies with all

applicable regulations, requirements, limitations, and provisions. If the Responsible

Person relinquishes responsibility, the LOA is no longer valid.

1.8.24 Supplemental Type Certificate (STC). An STC is a TC issued by the FAA to a person

who applies for a major change to a type design when the proposed change does not

require an application for a new TC under § 21.19. The STC, which incorporates by

reference the related TC, approves not only the modification but also how that

modification affects the original design.

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1.9 AC Feedback Form. For your convenience, the AC Feedback Form is the last page of

this AC. Note any deficiencies found, clarifications needed, or suggested improvements

regarding the contents of this AC on the Feedback Form.

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CHAPTER 2. MASTER MINIMUM EQUIPMENT LIST (MMEL)

2.1 General.

2.1.1 MEL Is Based on an MMEL. An M/M/S-specific MMEL is the document on which an

operator will base their aircraft-specific MEL. MMELs are developed for most FAA

type-certificated aircraft in general service today. Most multiengine airplanes have an

MMEL specific to their type design (e.g., Mitsubishi MU-2B).

2.1.2 Generic Single Engine Airplane MMEL. The FOEB has developed a generic

single-engine airplane MMEL for single-engine airplanes that do not have an

M/M/S-specific MMEL. The generic single-engine airplane MMEL cannot be used for an

airplane that has its own M/M/S-specific MMEL. If an operator is using the generic

single-engine airplane MMEL, and an MMEL is subsequently published for that specific

make and model single-engine airplane, the operator’s MEL must be revised to conform

to the new M/M/S-specific MMEL within 90 calendar-days of new M/M/S-specific

MMEL publication.

Note: Operators base their MEL on the MMEL applicable to the aircraft M/M/S

or the generic single-engine airplane MMEL, as appropriate.

2.1.3 Items Listed in an MMEL. The MMEL includes those items of equipment related to

airworthiness and operating regulations and other items of equipment, which may be

inoperative, and yet maintain an ALoS by appropriate conditions and limitations; it does

not contain obviously required items, such as wings and rudders. Additionally, an MMEL

does not include items required to be operative by an AD, unless the AD specifically

allows for their inclusion.

2.2 ATA/JASC Coded System Section Components. These sections are organized by

aircraft system according to the ATA or JASC coded numbering system (see Figure 2-1,

Example MMEL ATA/JASC Coded System Section Page) and contain the following

components:

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Figure 2-1. Example MMEL ATA/JASC Coded System Section Page

2.2.1 ATA/JASC System Code Numbers. MMEL system numbers use the ATA or JASC codes

that are standardized for each aircraft system. The ATA numbering system provides an

industrywide standard for numbering aircraft systems and is relevant for all aircraft. The

alternate format for aircraft system coding is the JASC codes, which are a modified

version of the ATA codes.

2.2.2 Individual Item Sequence Numbers. Individual item sequence numbers are the unique

identification for each item within an ATA/JASC system category. The numbering

scheme may be modified to align with the aircraft operator’s specific MEL format and

may differ from the MMEL. They are not required to match ATA/JASC system code

numbers. A triple asterisk (***) below the sequence number in the first column of an

MMEL indicates that an item, which is not required by regulation, has been installed on

some models of a particular aircraft.

2.2.3 Item. An item is an instrument, piece of equipment, a system, component, or function of

an instrument, piece of equipment, system, or component on an aircraft. An MMEL may

contain multiple versions of particular items (e.g., flight deck display systems, navigation

equipment, or engine instrumentation) installed on different models or series of the

aircraft covered by the MMEL.

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2.2.4 Repair Categories. The repair category intervals indicated by the letters A, B, C, and D in

column 1 of the MMEL are not applicable to an MEL approved under the provisions of

§ 91.213(a), but operators must comply with any provisos defining a repair interval

(e.g., flights, flight legs, cycles, hours, days, etc.). The operator must have any

inoperative items, which are permitted to be inoperative, either repaired, replaced,

removed, or inspected within the proviso-defined repair interval period, or at the next

required aircraft inspection, whichever comes first. Refer to § 91.405(c).

2.2.5 Number of Items Installed (Number Installed). Column 2 of an MMEL lists the number

(quantity) of the specified item normally installed on the aircraft. This number typically

represents the aircraft configuration used to develop the aircraft MMEL.

2.2.6 Variable Number Installed. A dash (-) for the number installed indicates a variable

number (quantity) of the installed item.

2.2.7 Number Required for Dispatch. Column 3 of an MMEL reflects the minimum number

(quantity) of items required to be operable for flight, provided the conditions specified in

the “Remarks or Exceptions” are met.

2.2.8 Variable Number of Items Required for Dispatch. A dash (-) indicates a variable number

required for dispatch.

2.2.9 Remarks or Exceptions. Column 4 includes provisos, notes, “as required by 14 CFR”

statements, and Maintenance (M) and Operations (O) symbols. Some MMEL “Remarks

or Exceptions” are intentionally general to accommodate a variety of operators and

operating rules.

2.3 Obtaining a Current MMEL. Operators may download MMELs from the “MMELs and

AED Guidance Documents” section in DRS at https://drs.faa.gov.

2.4 Aircraft for Which No MMEL Has Been Developed. Some aircraft, for which no

MMEL has been developed, may be operated under the provisions of § 91.213(d).

Note 1: Operators of single-engine reciprocating and turbine-powered airplanes

that do not have an MMEL for their specific M/M/S may use the generic

single-engine airplane MMEL.

Note 2: An operator may not operate an aircraft for which the FAA issued an

original experimental Airworthiness Certificate with inoperative items unless

specifically authorized in the aircraft’s operating limitations.

2.5 MMEL PLs. MMEL PLs communicate FAA policy for matters related to the

development and approval of MMELs and MELs. The primary audience for PLs is the

FOEB Chair and members. However, sometimes PLs apply to operators and are specific

to MEL considerations.

2.5.1 Mandatory MMEL PLs. Operators must include applicable information from MMEL

PL-25 (definitions) and MMEL PL-36 (preamble) in their MEL. See Chapters 7 and 8 for

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additional information. Except for MMEL PL-25 and PL-36, or unless specifically

mandated in the PL, an operator is not required to include MMEL PL information in their

MEL.

2.5.2 Where to Find MMEL PLs. Operators may download MMEL PLs from the “MMELs and

AED Guidance Documents” section in DRS at https://drs.faa.gov.

2.6 MMEL PL Global Change (GC) Designation. The FAA may designate an MMEL PL

as a GC for a variety of reasons, including the provision of immediate relief for items

required by a new regulatory requirement, policy change, or new technology. A GC

designation will not typically occur in great number or regularity, and their application

and use will typically be limited. The sole purpose of a GC designation is to allow

operators to obtain timely MEL relief for installed items referenced in an MMEL PL

prior to the release of a revised MMEL or applicable Design Change Approval Letter

(e.g., STC Relief Approval Letter). An operator is not required to include GC designation

relief in their MEL.

2.6.1 GC Designation Identification. MMEL PLs with a GC designation are identified by the

letters “GC” after the MMEL PL revision number on the title page. For example,

“MMEL PL-54, Revision 10 GC.” MMEL PLs with a GC designation will contain a

header box explaining their applicability (e.g., to what types of aircraft, operators, and/or

operations the GC applies). The header box will also contain requirements on how to

apply the sample proviso(s) of the GC to an operator’s MEL. See Figure 2-2.

Figure 2-2. Sample Global Change Header Box

MMEL GLOBAL CHANGE (GC)

This is an approved addendum to all existing MMEL documents. Operators may

seek use of the specific relief contained in this PL by revising their minimum

equipment list (MEL). In doing so, each applicable sample proviso stating the

relief in this PL must be copied verbatim in the operator’s MEL. Approval of a

revised MEL is gained utilizing established procedures through the assigned

Principal Operations Inspector (POI). This GC expires 9/13/2025.

2.6.2 GC Designation Applicability. An MMEL PL with a GC designation is typically

applicable to all aircraft. MMEL PLs will specify applicability (inclusion or exclusion)

when the GC designation is not applicable to all aircraft types. The Principal Operations

Inspector (POI) has the authority to approve the inclusion of an installed item in the

operator’s MEL on the basis that an MMEL PL with a current GC designation is an

approved addendum to the existing MMEL. The POI should contact the FOEB Chair

prior to approving the MEL if there is a concern about the applicability of the GC

designation for that specific aircraft.

2.6.3 GC Designation Expiration. The GC designation typically has an expiration date. The

expiration date may be extended by the FAA’s initiative or upon request by an FOEB

Chair. Keep in mind that even if the GC designation expires, the MMEL PL is still

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effective. In other words, the FOEB can continue to use an effective MMEL PL for

MMEL development and revision, however, after the expiration of a GC designation,

MEL relief through the MMEL PL is no longer available.

2.6.4 GC Designation Validity. The MEL relief available in an MMEL PL with a GC

designation is valid until any of the following occur:

• The aircraft’s MMEL is revised to include information in the applicable MMEL PL;

• An applicable Design Change Approval Letter is issued; or

• The MMEL PL GC designation expires.

Note: When the relief available in an MMEL PL with a GC designation is no

longer valid, the operator must ensure their MEL is not less restrictive than the

relief provided in the current MMEL or applicable Design Change Approval

Letter.

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CHAPTER 3. MINIMUM EQUIPMENT LIST (MEL)

3.1 General. An MEL allows an operator to continue to operate an aircraft with certain

inoperative items or to reposition the aircraft to a place where repairs can be made. The

MEL is intended to permit operations with inoperative items of equipment for the

minimum period of time necessary until repairs can be accomplished. It is important that

repairs be accomplished at the earliest opportunity in order to return the aircraft to its

design level of safety and reliability.

Note: Unless specified otherwise, the term “MEL,” used throughout this AC,

refers to both: (1) the MEL approval under LOA D095, consisting of an MMEL

and a procedures document, and (2) the MEL approval under LOA D195,

consisting of an operator-developed MEL. When required for clarity, this AC will

distinguish between an MEL approval under LOA D095 or D195 by using the

terms “procedures document,” or “operator-developed MEL,” respectively.

3.1.1 Requirement for All Aircraft Equipment to be Operative. Except as provided in

§§ 21.197 and 91.213(d), or under the provisions of an MEL and LOA, all instruments or

equipment items installed on an aircraft in compliance with the airworthiness standards or

operating rules must be operative for takeoff.

3.1.2 MEL Characteristics. An MEL and its associated LOA issued under the provisions of

§ 91.213(a) constitute an approved STC for the aircraft. An MEL allows an operator to

continue a flight (or series of flights) with certain items inoperative or to reposition to a

place where repairs can be made. An operator’s MEL may be more restrictive than the

MMEL, but it will not be less restrictive.

3.1.3 MEL Development and Content. MEL development is the responsibility of the operator.

Operators base their MEL on the MMEL applicable to the aircraft M/M/S, or the generic

single-engine airplane MMEL, as appropriate. When developing an MEL, the operator

should list all MMEL items for which the operator requests relief, based on their aircraft

configuration and operation. See Chapters 7 and 8 for detailed information concerning

MEL content. Except for NEF program items, MEL relief is only available for items

listed in:

1. The MMEL,

2. An applicable Design Change Approval Letter (e.g., STC Relief Approval Letter), or

3. An applicable MMEL PL with a current GC designation.

Note: See Chapter 10 for information on how to obtain relief for an item not

listed in items 1–3 above.

3.1.4 MEL Restrictions. An operator’s MEL will not be in any way less restrictive than the

following:

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• The MMEL from which it was developed;

• Title 14 CFR operating rule;

• The operator’s LOA D095 or D195;

• The approved flight manual limitations and emergency procedures;

• Applicable MMEL PLs with current GC designation;

• STC/instructions for continued airworthiness (ICA) (as applicable); and

• Applicable ADs.

3.1.5 MEL Conflicts with ADs. Occasionally, an AD applies to an item that may be authorized

to be inoperative under the MEL. In those cases, the operator must fully comply with the

terms of the AD or an FAA-approved alternative method of compliance (AMOC) with

the AD. When provisions of an AD allow operation of the aircraft on the condition

certain installed items be used or be operative, those affected items must be operative,

even if the MEL provides for the deferral of repair.

3.1.6 MEL Management Program Not Required. An operator, as defined by this AC, is not

required to have an MEL management program. However, a means of recording

discrepancies and corrective actions must be available to the pilot in command (PIC)

when operating under the provisions of § 91.213(a).

3.2 Three Methods for Operating an Aircraft with Inoperative Equipment.

Section 91.213 provides three methods for operating an aircraft with inoperative

instruments or equipment installed. The relief could be obtained:

• Through an MEL and LOA;

• Under the provisions of § 91.213(d); or

• Under a special flight permit (SFP) issued in accordance with §§ 21.197 and 21.199.

3.2.1 Experimental Aircraft. An operator may not operate an aircraft for which the FAA issued

an original experimental Airworthiness Certificate with inoperative items unless

specifically authorized in the aircraft’s operating limitations.

3.3 MEL LOA. The FAA indicates approval of an MEL under the provisions of § 91.213(a)

through the issuance of an LOA authorizing the operation of the specific aircraft with

inoperative items in accordance with the MEL and the conditions and limitations of the

LOA. The MEL and the LOA together constitute an STC for the aircraft.

3.3.1 LOA D095 Versus LOA D195. For aircraft operated under parts 91, 133, and 137

(including part 91 operations conducted by parts 141 and 142 CHs), the FAA provides

two types of approvals for MELs under the provisions of § 91.213(a): LOA D095 and

D195.

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3.3.1.1 MEL Approval Under LOA D095. The MEL approved under LOA D095

consists of the LOA, the aircraft M/M/S-specific MMEL, and the procedures

document. See Chapter 7 for detailed information regarding procedures

document content.

3.3.1.2 MEL Approval Under LOA D195. The MEL approved under LOA D195

consists of the LOA and the operator-developed MEL document, which is

based on the aircraft M/M/S-specific MMEL. See Chapter 8 for detailed

information on operator-developed MEL content.

3.3.2 Multiple Aircraft for a Single Operator. If an operator has multiple aircraft or more than

one type of aircraft, the aircraft serial number, registration number, and M/M/S will be

entered on the LOA for each aircraft. It is possible for an operator to have some aircraft

with an MEL approved under LOA D095 and other aircraft with an MEL approved under

LOA D195. Only one LOA D095 and one LOA D195 can be issued per operator.

3.3.3 Operational Control. LOAs are issued to the operator exercising operational control of

the aircraft. For example, under an aircraft dry lease agreement, the lessee assumes

operational control of the aircraft. Since the lessee is the operator of the aircraft, the

lessee may use only an MEL LOA specifically issued to them. The lessee cannot use an

MEL authorization issued to any other person (e.g., the lessor or another lessee).

3.3.4 Multiple Operators of a Single Aircraft. An MEL LOA is issued to a specific operator for

a specific aircraft. It is common for multiple operators to use a single aircraft on a

nonexclusive basis (e.g., multiple dry leases for the use of any one aircraft can be in place

at one time). In such instances, each individual operator is required to request an MEL

LOA in their own name. An operator may operate only under the MEL LOA issued to it.

Under timesharing, interchange, or joint ownership agreements, as defined in § 91.501(c),

the LOA is issued to the person exercising operational control.

3.4 Aircraft Operated Under Multiple 14 CFR Parts. Section 91.213(c) requires an

operator who has an approved MEL issued under either part 91K, 121, 125 (including

part 125 LODA holders), or 135 to use that MEL for part 91 operations. Only the

approved operator may use their MEL in part 91 operations. If a part 91K, 121, 125,

or 135 operator (the lessor) dry leases their aircraft to another operator (the lessee), the

lessee should obtain their own MEL since it cannot operate under the lessor’s MEL. MEL

authorizations are issued to the person exercising operational control.

3.5 Fleet MEL. An operator may develop a fleet MEL for multiple aircraft of the same

M/M/S. The operator is not required to list aircraft serial or registration numbers on a

fleet MEL. When a fleet MEL is used, aircraft of the same M/M/S may have differing

numbers of specific items installed. Operators may use a fleet MEL to reflect all of the

items applicable to a specific aircraft fleet type. This is allowable, provided the MMEL

applies to all of the M/M/S aircraft contained in the fleet. For example, the MMEL

applies to all Textron Aviation 500 Series Models: 500, 501, 550, S550, and 560 aircraft.

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3.5.1 Identify Each Model and Configuration Difference. A fleet MEL will identify each

aircraft configuration difference, when appropriate. Operators may use whatever

methodology they deem appropriate to distinguish the applicability of individual MEL

items to aircraft within the fleet. Methods include, but are not limited to, registration

number, serial number, pre/post-Service Bulletin (SB) accomplishment, or system

characteristics (e.g., three-display configuration and five-display configuration). The

method chosen should make it clear to users which individual MEL item applies.

3.5.2 Modifications Within a Fleet. The aircraft manufacturer determines the configuration of

the aircraft, items installed, and official parts listed during the initial aircraft type

certification process conducted at the time of manufacture. Any subsequent installation or

removal of items is accomplished through the use of an STC or other

FAA-approved/accepted data (as appropriate). Operators with a fleet MEL may continue

to operate under the provisions of the current fleet MEL with new items installed in one

or more fleet aircraft. However, operators may not defer repair of the new items until the

items are included in the MMEL and the fleet MEL is revised to include the additional

items.

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CHAPTER 4. CONDUCTING OPERATIONS WITHOUT AN MEL

4.1 Operating Without an MEL. This chapter provides guidance for operators who elect to

conduct flight operations under the provisions of § 91.213(d).

4.1.1 No Application Required. No application, written request, or approval is required to

operate under § 91.213(d).

4.1.2 Section 91.213(d). Operators who do not have an MEL per § 91.213(a) or (c) may takeoff

an aircraft with inoperative instruments or equipment items provided the conditions

detailed in § 91.213(d)(1)–(4) are met.

4.1.2.1 The following aircraft may be operated under § 91.213(d):

• Rotorcraft, non-turbine-powered airplane, glider, lighter-than-air aircraft,

powered parachute, or weight-shift-control aircraft, for which an MMEL

has not been developed.

• Small rotorcraft, non-turbine-powered small airplane, glider, or

lighter-than-air aircraft for which an MMEL has been developed.

4.1.2.2 Certain aircraft may not be operated under § 91.213(d), including:

• Turbine-powered airplanes.

• Large rotorcraft for which an MMEL has been developed.

• Large non-turbine-powered airplanes for which an MMEL has been

developed.

Note: An operator may not operate an aircraft for which the FAA

issued an original experimental Airworthiness Certificate with

inoperative items unless specifically authorized in the aircraft’s

operating limitations.

4.1.2.3 In addition to the above, § 91.213(d) requires:

• Instruments and equipment required by § 91.213(d)(2) must be operative;

• The maintenance action required by § 91.213(d)(3) has occurred; and

• A determination has been made in accordance with § 91.213(d)(4) that the

inoperative instrument or equipment does not constitute a hazard to the

aircraft.

4.2 Removal, Deactivation, and Placarding. When an operator elects to operate without an

MEL, any inoperative instrument or equipment items must either be repaired, removed,

deactivated, or inspected, and then placarded. Repair, removal, deactivation, or inspection

must be performed by a person authorized to perform aircraft maintenance in accordance

with § 43.3.

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4.2.1 Removal. Removal of any item requires an appropriately authorized person under § 43.7

to:

• Properly record the removal of the item in maintenance records in accordance with

§ 43.9;

• Properly adjust the aircraft’s W&B information and equipment list, if required;

• Placard the cockpit controls or indicators, as appropriate;

• Complete and submit an FAA Form 337, Major Repair and Alteration (Airframe,

Powerplant, Propeller, or Appliance), as appropriate; and

• Approve the aircraft for return to service, as appropriate.

4.2.2 Deactivation. When an item is “deactivated” or “secured,” or both, the specified item

must be put into an acceptable condition for safe flight. Deactivation may involve more

than simply turning off a system switch, which does not remove power from the system.

Deactivation may involve pulling and securing the circuit breaker and/or removing the

equipment. Deactivation of an inoperative system is not preventive maintenance as

described in part 43 appendix A. Regardless of the method of deactivation, a person

authorized to approve the aircraft for return to service under § 43.7 must make the

maintenance record entry required by § 43.9. No person may operate the aircraft without

the entry required by § 43.9.

• Only appropriately qualified maintenance personnel may conduct procedures

requiring specialized knowledge or skill, or requiring the use of tools or test

equipment. The satisfactory accomplishment of all maintenance procedures,

regardless of who performs them, is the responsibility of the operator.

• An appropriately authorized person must accomplish the deactivation.

4.2.3 Placarding. Each inoperative item must be placarded (e.g., marked “inoperative”) to

inform and remind the flightcrew and maintenance personnel of the item’s condition. To

the extent practical, placards will be securely affixed to a location adjacent to the control

or indicator for the item affected. The placard is not required to be in a particular form,

but it will be legible and visible to the flightcrew. The placard may not obscure other

controls or indicators and should not interfere with aircraft operation. Unless otherwise

specified, placard wording and location will be determined by the aircraft operator.

4.3 Continued Operation with Inoperative Items. The operator of the aircraft must ensure

any inoperative instrument or item of equipment, permitted to be inoperative by

§ 91.213(d)(2), is repaired, replaced, removed, or inspected at the next required

inspection, and when listed discrepancies include inoperative instruments or equipment,

shall ensure that a placard has been installed, as required by § 43.11.

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• The person performing the required inspection must give the aircraft owner or lessee

a signed and dated list of all discrepancies not repaired.

• The person performing the required inspection must ensure each inoperative item that

remains inoperative is placarded appropriately.

4.4 Safety Risk Analysis of Proposed Operation with Inoperative Equipment Items.

Before operating an aircraft with inoperative items permitted under § 91.213(d), the

operator should carefully evaluate whether the aircraft and crew are capable of safely

conducting the proposed operation under anticipated flight conditions with the

inoperative equipment. The safety risk analysis should include:

• A determination that the inoperative instrument or equipment, including failure

conditions, do not constitute a hazard to the operation;

• A determination that the inoperative instrument or equipment is not required for the

planned operation, such as oceanic/remote, or international operations;

• Interrelationship and effects of multiple instrument or equipment item failures;

• Adverse weather;

• Night operations;

• Departure and destination airports and their surrounding environment;

• En route environment;

• Diversion and alternate airport options;

• Additional crew workload caused by inoperative items; and

• Crew fatigue.

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Figure 4-1. PIC Decision Sequence

Figure 4-1 illustrates the sequence of events involved in operating an aircraft under § 91.213(d)

with inoperative items.

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CHAPTER 5. CONDUCTING OPERATIONS WITH AN MEL

5.1 Operating with an MEL. If the aircraft has an MEL and LOA, the PIC may defer

allowable inoperative items by following the MEL procedures. When operating under the

provisions of § 91.213(a), the MEL and LOA must be available to the PIC. The MEL

may be in hardcopy format (printed) or via another method approved by the

Administrator (e.g., electronically). Indirect methods of MEL and LOA access, such as

telephone, radio, or data link, are not acceptable.

5.1.1 Applicability. MEL item relief may be applied to an MEL item newly identified as

inoperative up until takeoff. Takeoff, for the purposes of this AC, is defined as the act of

beginning a flight in which an aircraft is accelerated from a state of rest to that of flight.

For the purposes of MEL relief, this means the point at which the pilot begins to apply

power to initiate the takeoff from the runway or takeoff surface.

5.1.2 Item Failures During or After Engine Start, During Taxi, or Any Time Prior to Takeoff.

The MEL does not allow a flight to continue if a discrepancy is discovered before

takeoff, but not yet not addressed by repair or deferral. An aircraft must not takeoff with

inoperative items until the MEL deferral process has been completed. For instance, if the

MEL procedures for a specific item require a mechanic’s inspection, takeoff would be

prohibited until the required inspection is complete.

5.1.3 Item Failures After Takeoff. MEL relief does not apply for item failures occurring after

takeoff. After takeoff, the flightcrew should handle item failures in accordance with the

Airplane Flight Manual (AFM)/Rotorcraft Flight Manual (RFM) approved procedures. A

record of the equipment failure must be made in the aircraft’s maintenance records.

Before the next takeoff, the inoperative item must either be repaired, or the PIC must

follow MEL deferral procedures. Therefore, any item failure that occurs after takeoff,

must be addressed before the subsequent takeoff.

5.1.4 Safety Risk Analysis of Proposed Operation with Inoperative Items. Before operating an

aircraft with inoperative items using an MEL, the operator should carefully evaluate

whether the aircraft and crew are capable of safely conducting the proposed operation

under anticipated flight conditions with the inoperative equipment. The safety risk

analysis should include, but is not limited to:

• A determination that the inoperative instrument or equipment, including the failure

condition, does not constitute a hazard to the operation;

• A determination that the inoperative instrument or equipment is not required for the

planned operation, such as oceanic, remote, or international operations;

• Interrelationship and effects of multiple instrument or equipment item failures;

• Adverse weather;

• Night operations;

• Departure and destination airports and their surrounding environment;

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• En route environment;

• Diversion and alternate airport options;

• Additional crew workload caused by inoperative items; and

• Crew fatigue.

5.2 Documentation of Deferred Items. A means of recording discrepancies and corrective

actions must be in the aircraft and available to the PIC when operating under the

provisions of § 91.213(a). Additionally, when an instrument or equipment item is

discovered to be inoperative, an entry must be made in the aircraft maintenance records.

Since some operators do not carry aircraft logbooks in the aircraft, a discrepancy record

or log is an acceptable alternative. When an operator uses this type of discrepancy log in

lieu of the aircraft maintenance records, the operator must retain the log as a part of the

aircraft’s records, per § 91.417(b). If the operator elects to use the aircraft maintenance

record to log inoperative items, that portion of the record must be carried onboard the

aircraft during all operations.

5.3 Placarding. Each inoperative item must be placarded (e.g., marked as “inoperative”) to

inform and remind the flightcrew and maintenance personnel of the item’s condition. To

the extent practical, placards will be securely affixed to a location adjacent to the control

or indicator for the item affected. The placard is not required to be in a particular form,

but will be legible and visible to the flightcrew; may not obscure other controls or

indicators; and should not interfere with aircraft operation. Unless otherwise specified

(e.g., in an MEL proviso), placard wording and location will be determined by the aircraft

operator.

5.4 Performing (M) and (O) Procedures. The presence of either (M) or (O) symbols (as

explained below) in the “Remarks or Exceptions” column of the MEL indicate a specific

(M) or (O) procedure is required to be accomplished. In addition to carrying the

documents that comprise the MEL onboard the aircraft, the operator must have available

any applicable technical manuals needed to accomplish (M) and (O) procedures when

operating under the provisions of § 91.213(a).

5.4.1 (M) Procedures. The (M) symbol indicates a specific maintenance procedure that must be

accomplished prior to operation with the listed item inoperative. Normally, (M)

procedures are accomplished by qualified maintenance personnel; however, other

personnel may be qualified and authorized to perform certain functions. Procedures

requiring specialized knowledge or skill, or requiring the use of tools or test equipment,

should be accomplished by maintenance personnel. The satisfactory accomplishment of

all (M) procedures, regardless of who performs them, is the responsibility of the aircraft

operator. Appropriate procedures are required as a part of the aircraft operator’s MEL.

5.4.2 (O) Procedures. The (O) symbol indicates a specific operations procedure that must be

accomplished prior to operation with the listed item inoperative. Normally, these

procedures are accomplished by the flightcrew; however, other personnel may be

qualified and authorized to perform certain functions. These procedures may be required

for flight planning purposes, or they may require action by the flightcrew. Additionally,

DATE “DRAFT” AC 91-67A

5-3

MEL items affecting the aircraft W&B and cargo loading may require procedures for

additional personnel, such as those involved with aircraft load control. The satisfactory

accomplishment of all (O) procedures, regardless of who performs them, is the

responsibility of the aircraft operator. Appropriate procedures are required as a part of the

aircraft operator’s MEL.

5.5 Repair of Deferred Instruments or Equipment Items. The MEL is intended to permit

operations with inoperative items for the minimum period of time necessary until repairs

can be accomplished. It is important repairs be accomplished at the earliest opportunity in

order to return the aircraft to its design level of safety and reliability.

5.5.1 Accomplishing Repair, Replacement, Removal, or Inspection of Deferred Items. The

repair category intervals indicated by the letters A, B, C, and D in column 1 of the

MMEL are not applicable to an MEL approved under the provisions of § 91.213(a), but

operators must comply with any provisos defining a repair interval (e.g., flights, flight

legs, cycles, hours, days, etc.). The operator must have any inoperative items, which are

permitted to be inoperative, either repaired, replaced, removed, or inspected within the

proviso-defined repair interval period or at the next required aircraft inspection,

whichever comes first. If an operator chooses to defer maintenance on an inoperative

item beyond a required aircraft inspection, certificated maintenance personnel must

inspect the item for conformance with the requirements of the MEL and § 43.11(b).

• The person performing the required inspection must give the aircraft owner or lessee

a signed and dated list of all discrepancies not repaired.

• The person performing the required inspection must ensure each inoperative item that

remains inoperative is placarded appropriately.

DATE “DRAFT” AC 91-67A

5-4

Figure 5-1. PIC Decision Sequence

Figure 5-1 illustrates the sequence of events involved in using an MEL to operate an aircraft with

inoperative items. This chart is not required to be part of the operator’s MEL.

The PIC must ensure all applicable (M) and/or (O) procedures are performed and must

comply with applicable conditions or limitations listed in the “Remarks or Exceptions”

column of the MEL.

DATE “DRAFT” AC 91-67A

6-1

CHAPTER 6. APPLICATION FOR MEL LETTER OF AUTHORIZATION (LOA)

6.1 Application for an MEL Approval Issued Under LOA D095. An operator applying for

an MEL approval issued under LOA D095 must submit a signed, written request for

issuance of LOA D095 to the responsible Flight Standards office having jurisdiction over

the area in which the operator’s principal base of operations is located. An electronic

signature, or a signed and scanned request transmitted via email is acceptable. The

operator’s request must contain the information described in Figure 6-1, Sample

LOA D095 Request Letter. Except for reapplication after cancellation, rescission, or

revocation, the operator is not required to submit the procedures document to the FAA.

See Chapter 7 for detailed information on the procedures document content.

6.2 Application for an MEL Approval Issued Under LOA D195. An operator applying for

an MEL approval issued under LOA D195 must submit a signed, written request for

issuance of LOA D195, along with a copy of the operator-developed MEL (an electronic

copy is preferred), to the responsible Flight Standards office having jurisdiction over the

area in which the operator’s principal base of operations is located. An electronic

signature, or a signed and scanned request transmitted via email is acceptable. The

operator’s request must contain the information described in Figure 6-2, Sample

LOA D195 Request Letter for an Operator-Developed MEL That Conforms to the

Content Described in AC 91-67. Operators who conduct international operations and

currently hold an LOA D095 should state so in their request letter. See Chapter 8 for

detailed information on operator-developed MEL content.

6.3 Request for Approval of an MEL That Does Not Conform to This AC. An operator

may request approval of an operator-developed MEL that does not conform to the content

described in this AC. If an operator-developed MEL does not conform to the content

described in this AC, the operator should:

1. Submit a signed, written request to the responsible Flight Standards office for

approval of an MEL that does not conform to this AC (see Figure 6-3, Sample MEL

Approval Request Letter for an Operator-Developed MEL That Does Not Conform to

the Content Described in AC 91-67);

2. Explain in their request letter how their MEL meets the requirements of § 91.213(a);

3. Provide a copy of the operator-developed MEL (an electronic copy is preferred) with

the request; and

4. Be advised that approval of the MEL may be delayed.

6.4 Oversight. The FAA may request to review a procedures document or

operator-developed MEL during normal surveillance activity. If the FAA determines the

MEL does not comply with the conditions and limitations of the operator’s MEL LOA,

the FAA may rescind the LOA.

DATE “DRAFT” AC 91-67A

6-2

Figure 6-1. Sample LOA D095 Request Letter

To: Responsible Flight Standards Office

I request issuance of a Letter of Authorization (LOA) D095 under the provisions of Title 14 of

the Code of Federal Regulations (14 CFR) part 91, § 91.213 to [complete legal name of operator]

for the aircraft listed below.

I attest that I have a copy of the [state the make, model, series (M/M/S) Master Minimum

Equipment List (MMEL), revision number (e.g., Gulfstream Aerospace GVII-G500/G600

MMEL, revision 3)] and have developed a procedures document for the listed aircraft. The

procedures document conforms to the content described in Advisory Circular (AC) 91-67, and

contains:

1. The name(s) of the operator(s), aircraft serial and registration numbers (or “Fleet”),

aircraft M/M/S, and the MMEL revision number on which the minimum equipment list

(MEL) is based;

2. Maintenance (M) and Operations (O) procedures that correspond with the (M) and (O)

provisos listed in the MMEL;

3. A list of applicable MMEL items that contain the statement “as required by 14 CFR”;

4. Definitions, per current MMEL Policy Letter (PL)-25; and

5. A preamble, per current MMEL PL-36.

Principal base of operations address of the operator:

[Mailing address of the operator, if different from the principal address]:

Responsible Person’s full name, email address, and/or telephone number [part 91 only]:

Aircraft serial number:

Aircraft registration number:

Aircraft M/M/S:

[List information for additional aircraft, if applicable]

Sincerely,

[Signature]

[Full name of the person legally authorized to make the request on behalf of the operator]

DATE “DRAFT” AC 91-67A

6-3

Figure 6-2. Sample LOA D195 Request Letter for an Operator-Developed MEL That

Conforms to the Content Described in AC 91-67

To: Responsible Flight Standards Office

I request issuance of a Letter of Authorization (LOA) D195 under the provisions of Title 14 of

the Code of Federal Regulations (14 CFR) part 91, § 91.213 to [complete legal name of operator]

for the aircraft listed below.

I attest that the attached minimum equipment list (MEL) conforms to the content described in

Advisory Circular (AC) 91-67, is based on the [state the make, model, series (M/M/S) Master

Minimum Equipment List (MMEL), revision number (e.g., Gulfstream Aerospace

GVII-G500/G600 MMEL, revision 3)], is not less restrictive than the MMEL, and contains:

1. The name(s) of the operator(s), aircraft serial and registration numbers (or “Fleet”),

aircraft M/M/S, and the MMEL revision number on which the MEL is based;

2. A table of contents;

3. A log of revisions;

4. Definitions, per current MMEL Policy Letter (PL)-25;

5. A preamble, per current MMEL PL-36;

6. Control page(s);

7. Air Transport Association of America (ATA) [or Joint Aircraft System/Component

(JASC)] coded system sections;

8. Maintenance (M) and Operations (O) procedures that correspond with the (M) and (O)

provisos listed in the MMEL; and

9. Applicable MMEL items that contain the statement “as required by 14 CFR.”

Principal base of operations address of the operator:

[Mailing address of the operator, if different from the principal address]:

Responsible person’s full name, email address, and/or telephone number [part 91 only]:

Aircraft serial number:

Aircraft registration number:

Aircraft M/M/S:

[List information for additional aircraft, if applicable]

Sincerely,

[Signature]

[Full name of the person legally authorized to make the request on behalf of the operator]

DATE “DRAFT” AC 91-67A

6-4

Figure 6-3. Sample LOA D195 Request Letter for an Operator-Developed MEL That Does

Not Conform to the Content Described in AC 91-67

To: Responsible Flight Standards Office

I request review and approval of a Title 14 of the Code of Federal Regulations (14 CFR) part 91

minimum equipment list (MEL) that does not conform to the content described in Advisory

Circular (AC) 91-67. Upon review and approval, I request issuance of Letter of Authorization

(LOA) D195 under the provisions of part 91, § 91.213 to [complete legal name of operator] for

the aircraft listed below.

[Explain how the MEL conforms to the requirements of § 91.213(a)]

I have attached the proposed MEL for your review and approval.

Principal base of operations address of the operator:

[Mailing address of the operator, if different from the principal address]

Responsible Person’s full name, email address, and/or telephone number [part 91 only]:

Aircraft serial number:

Aircraft registration number:

Aircraft make, model, and series (M/M/S):

[List information for additional aircraft, if applicable]

Sincerely,

[Signature]

[Full name of the person legally authorized to make the request on behalf of the operator]

DATE “DRAFT” AC 91-67A

7-1

CHAPTER 7. CONTENT OF A PROCEDURES DOCUMENT

7.1 MEL Approval Under LOA D095. The MEL approved under LOA D095 consists of

three documents: the LOA, the aircraft M/M/S-specific MMEL, and the procedures

document.

Note: Operators may include MMEL PLs with a current GC designation, Design

Change Approval Letters, or any design change approval described in Chapter 11,

as an attachment to the MMEL.

7.2 Procedures Document Content. This chapter provides information to ensure the

procedures document meets the requirements listed in LOA D095.

1. The procedures document must contain the name(s) of the operator(s), aircraft serial

and registration numbers (or “Fleet”), aircraft M/M/S, and the MMEL revision

number on which the MEL is based.

2. The procedures document must include specific content based on the items installed

on the operator’s aircraft. The procedures document may omit an MMEL item if the

item or configuration is not installed or if the operator elects to not take relief. If the

operator does not take relief for an installed item, the procedures document will

clearly state that no MEL relief is provided for that item and it must be operative for

takeoff.

3. A procedures document should incorporate the phraseology used in the MMEL,

wherever appropriate, to ensure clarity and standardization.

7.3 Procedures Document Required Sections. The procedures document must contain the

following sections:

7.3.1 (M) and (O) Procedures. The presence of either (M) or (O) symbols in the MMEL

“Remarks or Exceptions” column indicates specific (M) or (O) procedures are required to

be accomplished prior to operation when the item is inoperative. The procedures

document must contain (M) and (O) procedures corresponding to the (M) and (O)

provisos listed in the MMEL for all installed equipment for which the operator desires

MEL relief. The procedures document’s (M) and (O) procedures:

1. Must meet the intent of the (M) and (O) provisos in the MMEL.

2. Must never be less restrictive than the (M) and (O) provisos in the MMEL.

3. May be either manufacturer’s (M) and (O) procedures or operator-developed (M) and

(O) procedures.

Note: It is recommended, although not required, that operators use the Original

Equipment Manufacturer’s (OEM) document (e.g., maintenance operational

placarding procedures (MOPP), dispatch deviation guide (DDG), or maintenance

policy manual (MPM)) as the required (M) and (O) procedures element.

DATE “DRAFT” AC 91-67A

7-2

4. May be developed from the manufacturer’s (M) and (O) procedures or the guidance

provided in the manufacturer’s AFM, RFM, or Aircraft Maintenance Manual

(AMM), manufacturer’s recommendations, engineering specifications, or other

appropriate sources. Operators are not required to copy the manufacturer’s

recommended (M) and (O) procedures verbatim in their MEL. When a

manufacturer-recommended procedure exists, the operator may use it as published or

develop equivalent procedures for their procedures document.

5. Must comply with all 14 CFR requirements and must not deviate from the AFM/RFM

limitations, emergency procedures, or ADs, all of which take precedence over the

MEL.

6. Must specify suitable conditions and limitations in the form of placards, maintenance

procedures, crew operating procedures, and other restrictions, which must be

accomplished by the operator to ensure an ALoS is maintained.

7. May reference a procedure in an FAA-approved or FAA-accepted manual. The

manual reference must be preceded by a specific instruction defining the action

required and direct the use of that manual to include specific chapter, section, task, or

paragraph references for the procedure.

7.3.2 As Required by 14 CFR. An operator must develop a list of all MMEL items containing

the statement “as required by 14 CFR” or any similar statement, based on the items

installed on the operator’s aircraft for which the operator desires MEL relief. The

procedures document will: (1) list the specific 14 CFR part and section (e.g., 14 CFR

part 91, § 91.209) (and the operator must carry the applicable 14 CFR section on board

the aircraft), or (2) specify the requirements and/or limitations to conduct the flight in

accordance with the appropriate 14 CFR regulations. MMEL PL-25 contains a list of

regulatory references according to the ATA chapter number. This list is not all-inclusive.

Note: The term “14 CFR” has replaced “Federal aviation regulations (FAR)” as

the current reference to Federal regulations pertaining to aviation. Many MMELs

and MELs still contain the acronym “FAR” and should be updated to “14 CFR”

as they are revised.

7.3.3 Definitions. MMEL and MEL definitions are contained in MMEL PL-25. Operators must

include all applicable definitions in their procedures document. Not all of the MMEL

definitions are required to be in a procedures document, as some are related to format

issues, specific aircraft types, and certain types of operations. Certain portions of an

MMEL definition may be edited or are not required, but the intent of the definition must

be the same and must not be less restrictive than the definition in MMEL PL-25.

Operators may download MMEL PLs from the “MMELs and AED Guidance

Documents” section in DRS at https://drs.faa.gov.

7.3.4 Preamble. The preamble contained in MMEL PL-36 is applicable to all § 91.213(a) MEL

approvals under LOA D095. This preamble must be reproduced verbatim in the

procedures document.

DATE “DRAFT” AC 91-67A

7-3

7.4 Procedures Document Optional Sections. An operator may include the optional

sections listed below. The operator may also include additional sections containing

information relevant to their MEL.

7.4.1 Cover Page. The cover page format and information may be the same as the MMEL. The

cover page content and format may vary due to operator preference.

7.4.2 Table of Contents. The table of contents is a list of all the sections/chapters in the

procedures document by title and the corresponding page identification. The format may

vary due to operator preference.

7.4.3 Log of Revisions. The log of revisions contains the revision identification (typically a

number and/or letter) and the date of the revision. At the operator’s discretion, it may also

contain a list of the revised pages, a block for the initials of the person posting the

change, and additional enhancements for use by the operator. The format may vary due to

operator preference.

7.4.4 Control Page (List of Effective Pages (LEP)). Control pages are used for tracking the

status of the MEL and include a record of the revision status or the date of each page of

the operator’s MEL. The format may vary due to operator preference.

7.4.5 Highlights of Change Page. This page list contains a summary of the changes made by

the operator in each revision.

7.5 Example “As Required by 14 CFR” and (M) and (O) Procedures. Figures 7-1(a)

through 7-3(b) are examples of MMEL and corresponding procedures document “as

required by 14 CFR” and (M) and (O) procedures. These are examples only and are not

intended to be used or depicted as actual MMEL or procedures document procedures.

Figure 7-1(a). Example MMEL “As Required by 14 CFR” Statement

Sequence No. Item

1 2 3 4

Change

Bar

33-07

Landing Light C - 0

34. NAVIGATION

As required by 14 CFR

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

DATE “DRAFT” AC 91-67A

7-4

Figure 7-1(b). Example Procedures Document “As Required by 14 CFR” Regulatory

Reference or Requirement/Limitation

34-33-07: 14 CFR Reference: 14 CFR 91.205(c)(4) and 91.205(d)(1).

[And carry the applicable 14 CFR section on board the aircraft.]

34-33-07: The landing light must be operative for night flight operations if the

aircraft is being operated for hire.

Note: Illustrated in the examples above, the procedures document will: (1) list the

specific 14 CFR part and section (and the operator must carry the applicable

14 CFR section on board the aircraft), or (2) specify the requirements and/or

limitations to conduct the flight in accordance with the appropriate 14 CFR

regulations.

Figure 7-2(a). Example 1 MMEL Maintenance (M) and Operations (O) Symbols and

Provisos

Sequence No. Item

1 2 3 4

Change

Bar

-30-01 Thrust Reverser C 2 0

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

78. Engine Exhaust

(M)(O) May be inoperative provided:

a) Affected thrust reverser is locked in the

forw

ard thrust position, and

b) Appropriate performance penalties are

applied.

Figure 7-2(b). Example 1 Procedures Document Maintenance (M) and Operations (O)

Procedures

78-30-01:

Maintenance (M) Procedure

Lock affected thrust reverser in the forward thrust position in accordance

with AMM 78-30-12.

Operations (O) Procedure

Refer to AFM Performance Section, Thrust Reverser inoperative for

applicable takeoff and landing penalties.

Note: AMM 78-30-12 and the AFM in the above example are FAA-approved or

FAA-accepted manuals.

DATE “DRAFT” AC 91-67A

7-5

Figure 7-3(a). Example 2 MMEL Maintenance (M) Symbol and Proviso

Sequence No. Item

1 2 3 4

Change

Bar

28-21-25 XBP Crossfeed Valve A 2 0

28. FUEL

(M) One or more may be inoperative in

closed position provided:

a) Al

l Booster Pumps are operative,

b) Affected XBP Crossfeed Valve is secured

in closed position, and

c) Repairs are made within 3 consecutive

calendar-days.

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

Figure 7-3(b). Example 2 Procedures Document Maintenance (M) Procedure

28-21-25:

Maintenance (M) Procedure

CROSSFEED VALVE IN CLOSED POSITION:

1. Open the door 170AB.

2. Check that the inoperative XBP crossfeed valve (400QS/410QS) is in

close position (“C”).

NOTE: If not, set the valve to close (“C”) using the lever.

3. Disconnect the electrical connector.

4. Close the door 170AB.

NOTE: Place inoperative placard near MDU.

DATE “DRAFT” AC 91-67A

8-1

CHAPTER 8. CONTENT OF AN OPERATOR-DEVELOPED MEL

8.1 MEL Approval Under LOA D195. The MEL approved under LOA D195 consists of

two documents: the LOA and the operator-developed MEL.

8.2 MEL Content. This chapter provides detailed content requirements to ensure the

operator-developed MEL meets the requirements listed in LOA D195.

1. The MEL must contain the name(s) of the operator(s), aircraft serial and registration

numbers (or “Fleet”), aircraft M/M/S, and the MMEL revision number on which the

MEL is based.

2. Operators may copy the MMEL format outline directly into their MEL. An operator

may also customize their MEL format, provided the format does not make the MEL

in any way less restrictive than the MMEL. An MEL may contain corrections to

MMEL typos, spelling, and punctuation errors.

3. The MEL must include specific content based on the items installed on the operator’s

aircraft. The aircraft operator’s MEL may omit an MMEL item if the item or

configuration is not installed or if the operator elects to not take relief.

4. If an operator elects to take relief for items listed in MMEL PLs with a current CG

designation, Design Change Approval Letters (e.g., STC Relief Approval Letter), or

any design change approval described in Chapter 10, the MEL must comply with the

requirements of paragraph 8.5 below for those items.

5. The MEL should incorporate the phraseology used in the MMEL, wherever

appropriate, to ensure clarity and standardization.

8.3 MEL Required Sections. The operator-developed MEL must contain the following

sections:

8.3.1 Table of Contents. The table of contents is a list of all sections/chapters in the MEL by

title and the corresponding page identification. The format may vary due to operator

preference.

8.3.2 Log of Revisions. The log of revisions contains the MEL revision identification (typically

a number and/or letter) and the date of the MEL revision. At the operator’s discretion, it

may also contain a list of the revised pages, a block for the initials of the person posting

the change, and additional enhancements for use by the operator. The format may vary

due to operator preference.

8.3.3 Definitions. Definitions of the terms used in MMELs and MELs are found in MMEL

PL-25. Operators must include all applicable definitions in their MEL. Not all of the

MMEL PL-25 definitions are required to be in an operator’s MEL, as some are related to

format issues, specific aircraft types, and certain types of operations. Certain portions of a

definition may be edited or are not required, but the intent of the definition must be the

same and must not be less restrictive than the definition in MMEL PL-25. Operators may

download MMEL PLs from the “MMELs and AED Guidance Documents” section in

DRS at https://drs.faa.gov.

DATE “DRAFT” AC 91-67A

8-2

8.3.4 Preamble. The preamble contained in MMEL PL-36 is applicable to all § 91.213(a) MEL

approvals under LOA D195. This preamble must be reproduced verbatim in the MEL.

8.3.5 Control Page (LEP). Control pages are used for tracking the status of the MEL and

include a record of the revision status or the date of each page of the operator’s MEL. It

may also be used as a means of conveying FAA approval of the MEL. The format may

vary due to operator preference. At a minimum, control pages must contain:

• The name(s) of the operator(s);

• A listing of all of the pages in the MEL (individually or the range of applicable pages

for a given section/chapter), including the date of all pages and their number or

revision number; and

• The MMEL revision number on which the MEL is based.

8.3.6 ATA/JASC Coded System Sections. These sections are organized by aircraft system

according to the ATA/JASC coded numbering system and include individual item

sequence numbers, items, repair categories, number of items installed, number of items

required for dispatch, remarks or exceptions, and (M) and (O) procedures. See

paragraph 8.5 below for additional information.

8.4 MEL Optional Sections. The operator-developed MEL may include the optional

sections listed below. The operator may also include additional sections containing

information relevant to their MEL.

8.4.1 Cover Page. The cover page format and information may be the same as the MMEL.

8.4.2 Highlights of Change Page. This page list contains a summary of the changes made by

the operator in each revision.

8.5 ATA/JASC Coded System Sections. The operator-developed MEL must be organized

using the MMEL ATA/JASC coded numbering system. The MEL ATA/JASC coded

system sections will include a list of individual items in the aircraft, together with

requirements for operation when the items are inoperative. Each coded system section

will be further broken down into individual item sequence numbers.

8.5.1 ATA/JASC System Code Numbers. Operators must use the ATA or JASC coded

numbering system. The ATA/JASC numbering system provides an industrywide standard

for numbering aircraft systems and is relevant for all aircraft.

8.5.2 Individual Item Sequence Number and Items. Individual item sequence numbers are the

unique identification for each item within an ATA/JASC system category. The

numbering scheme may be modified to align with the aircraft operator’s specific MEL

format and may differ from the MMEL. They are not required to match ATA/JASC

system item numbers.

DATE “DRAFT” AC 91-67A

8-3

8.5.2.1 A triple asterisk (***) below the system number in column 1 of an MMEL

indicates an item that is not required by regulation has been installed on some

models of a particular aircraft M/M/S. An operator may not carry the “***”

symbol over to the MEL. Operators omit the symbol and use a system

sequence number when the item is installed on one or more of the operator’s

aircraft.

8.5.2.2 An operator is not required to list all MMEL items in their MEL; however, if a

particular item is not in the operator’s MEL, then the item must be fully

operative at takeoff.

8.5.2.3 Operators may add limitations and restrictions to a particular item beyond

what is required by the MMEL. An operator’s MEL limitations, conditions,

and restrictions must never be less restrictive than the MMEL.

8.5.2.4 Operators will typically list an MEL item exactly as it is in the MMEL. If an

MMEL uses a generic term to describe a particular item, an operator may use

different terminology, provided the operator’s terminology is recognizable

and easily identified with the corresponding MMEL item.

8.5.2.5 When an MEL item contains multiple components, those components may be

listed separately following the item in the MEL.

8.5.2.6 Operators must not list duplicate items, or items listed individually elsewhere

in the MMEL.

8.5.2.7 Individual components of an MMEL or MEL item may not be listed as NEF.

8.5.3 Repair Categories. The repair category intervals indicated by the letters A, B, C, and D in

column 1 of the MMEL are not applicable to an operator-developed MEL, but operators

must comply with any provisos defining a repair interval (e.g., flights, flight legs, cycles,

hours, days, etc.). At an operator’s discretion, repair category interval letters (e.g., A, B,

C, or D) may be omitted from the MEL. If an operator chooses to include repair

categories in their MEL, they may comply with the repair category intervals as a best

practice, but they are not mandatory. Inoperative equipment in all cases must be repaired,

replaced, removed, or inspected by qualified maintenance personnel at the next required

inspection. Refer to § 91.405(c).

8.5.4 Number of Items Installed (Number Installed). The “Number Installed” column of an

MEL lists the number (quantity) of the specified item installed on the aircraft.

8.5.4.1 Variable Number Installed. A dash (-) for the number installed indicates a

variable number (quantity) of the installed item. The use of a dash (-) is

common in fleet MELs where aircraft of the same M/M/S have differing

numbers of specific items. A dash (-) is also used for MEL items that provide

relief for fault messages (e.g., Crew Alert System (CAS), engine indicating

and crew alerting system (EICAS), and electronic centralized aircraft

monitoring (ECAM)). Additionally, operators may use a dash (-) if it is

DATE “DRAFT” AC 91-67A

8-4

impractical to show the actual number of the specific items (including but not

limited to light bulbs, light-emitting diodes (LED), cabin storage

compartments, and cargo lining panels) installed on the aircraft.

8.5.4.2 Items Listed on the MMEL but Not Installed on the Aircraft. An

operator’s MEL does not have to list MMEL items not installed on the

operator’s aircraft. For number continuity in an MEL, operators may choose

to:

1. Simply omit the item from the MEL altogether. The option to either

renumber the subsequent individual items or maintain the original MMEL

sequence numbering is at the operator’s discretion.

2. List the item in the MEL and then show the “Number Installed” as

zero (0). In this case, the “Number Required for Dispatch” would also be

zero (0), and the remark “Not Installed” noted under “Remarks or

Exceptions.” Additionally, in this case, the repair category designators

would be omitted.

8.5.5 Number Required for Dispatch. The “Number Required for Dispatch” column of an MEL

reflects the minimum number (quantity) of items required for flight, provided the

conditions specified in the “Remarks or Exceptions” are met. The number of items

required for dispatch in an MEL may differ from what is required in the MMEL under the

following conditions:

1. The item is listed in the MMEL as optional and is not installed on the aircraft. In this

case, a zero (0) may be shown as the number required, the “Number Installed” shown

as zero (0), and the remark “Not Installed” noted under “Remarks or Exceptions.”

Note: An operator’s MEL does not have to list MMEL items not installed on the

operator’s aircraft.

2. The “Number Required for Dispatch” is followed by a dash (-) in the MMEL. Where

the MMEL shows a variable number (-) required for dispatch, the MEL may reflect

the actual number required for dispatch or an alternate means of configuration control

approved by the Administrator. An aircraft operator’s MEL may contain a dash (-)

where the number required is based on the conditions of flight, such as adequate

cockpit lighting. Fleet configuration differences (where applicable) and the dispatch

requirements must be specified in the “Remarks or Exceptions” section.

3. The number required for dispatch in the MEL is not less restrictive than the MMEL.

8.5.6 Remarks or Exceptions. The “Remarks or Exceptions” column includes provisos, notes,

“as required by 14 CFR” requirements and/or limitations, and (M) and (O) symbols.

Some MMEL “Remarks or Exceptions” are intentionally general to accommodate a

variety of operators and operating rules. An MEL must expand upon these general

MMEL “Remarks or Exceptions,” as required to adequately and safely address an

operator’s particular operations and operating rules. See the examples in paragraph 8.6

below.

DATE “DRAFT” AC 91-67A

8-5

8.5.6.1 Provisos. Provisos are conditions or limitations that must be complied with

for operation with the listed item inoperative. The term indicates by

association that an item may be deferred, provided that certain conditions are

met. If more than one proviso applies, they will be listed separately by number

or lowercase letter. For example, a proviso may allow an item to be

inoperative provided the airplane is not operated in Extended Operations

(ETOPS); and another proviso requires the aircraft only be operated under

VFR when that same item is inoperative. In most instances, MEL provisos

will be written verbatim from the MMEL, but there are cases where it is

acceptable to deviate from the MMEL. However, in every case, the operator

MEL will not be less restrictive than the MMEL or the relevant 14 CFR

requirement. For example, deleting “established and” from the phrase

“alternate procedures are established and used” would not be less restrictive

since the inclusion of the procedure in the MEL meets the requirement to

“establish” the procedure.

8.5.6.2 Notes. Notes provide additional information for flightcrew or maintenance

consideration. Notes are used to identify applicable material intended to assist

with compliance but do not relieve the aircraft operator of the responsibility

for compliance with all applicable requirements. Additional notes may be

added to the aircraft operator’s MEL, as appropriate. Some notes in the

MMEL may not be appropriate in an aircraft operator’s MEL and may be

amended or deleted. Notes are not a part of the proviso. Where more than one

note is included, they will be numbered accordingly (e.g., NOTE 1, NOTE 2).

Notes are repeated, as necessary, following each applicable proviso.

8.5.6.2.1 Notes may contain a suggestion to aid with compliance such as: “The

operator’s alternate procedures should include reviewing wind shear

avoidance and wind shear recovery procedures.”

8.5.6.2.2 Notes may be more specific such as: “Flight level (FL) 310 or below must be

maintained if normal operating pack fails,” or, “When FCMC 2 is inoperative,

fuel quantity indication can have dashes on the two last digits.”

8.5.6.2.3 As appropriate, the operator includes the MMEL note in the MEL, or bases

their (M) and (O) procedures on the information contained in the note.

8.5.6.2.4 The information within a note must remain within the scope of the definition

of “notes” in MMEL PL-25.

8.5.6.3 As Required by 14 CFR. The MEL must address all items listed in the

MMEL containing the statement “as required by 14 CFR,” or any similar

statement, based on the items installed on the operator’s aircraft for which the

operator desires MEL relief. The MEL will: (1) list the specific 14 CFR part

and section (e.g., 14 CFR part 91, § 91.209) and the operator must carry the

applicable 14 CFR section on board the aircraft, or (2) specify the

requirements and/or limitations to conduct the flight in accordance with the

DATE “DRAFT” AC 91-67A

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appropriate 14 CFR regulations. The phrase “as required by 14 CFR,” or any

similar statement, is prohibited in an MEL. MMEL PL-25 contains a list of

regulatory references according to ATA chapter number. This list is not

all-inclusive.

Note: The term “14 CFR” has replaced “Federal aviation regulations

(FAR)” as the current reference to Federal regulations pertaining to

aviation. Many MMELs and MELs still contain the acronym “FAR”

and should be updated to “14 CFR” as they are revised.

8.5.6.4 (M) and (O) Symbols and Procedures. The presence of either (M) or (O)

symbols in the MMEL “Remarks or Exceptions” column indicates specific

(M) or (O) procedures are required to be accomplished prior to operation with

the listed item inoperative. The MEL must contain (M) and (O) procedures

corresponding to the (M) and (O) provisos listed in the MMEL for all installed

equipment for which the operator desires MEL relief.

8.5.6.5 MEL (M) and (O) Procedures. The MEL (M) and (O) procedures:

1. Must meet the intent of the (M) and (O) provisos in the MMEL.

2. Must never be less restrictive than the (M) and (O) provisos in the MMEL.

3. May be either manufacturer’s (M) and (O) procedures or

operator-developed (M) and (O) procedures.

4. May be developed from the manufacturer’s (M) and (O) procedures or the

guidance provided in the manufacturer’s AFM, RFM, or AMM,

manufacturer’s recommendations, engineering specifications, and other

appropriate sources. Operators are not required to copy the manufacturer’s

recommended (M) and (O) procedures verbatim in their MEL. When a

manufacturer-recommended procedure exists, the operator may use it as

published or develop equivalent procedures for their procedures

document.

5. Must comply with all 14 CFR requirements and must not deviate from the

AFM/RFM limitations, emergency procedures, or AD, all of which take

precedence over the MEL.

6. Must specify suitable conditions and limitations in the form of placards,

maintenance procedures, crew operating procedures, and other restrictions,

which must be accomplished by the operator. As part of the review and

approval process, the FAA may ask the operator to include additional

instructions within the provisos to ensure that deferral procedures will

continue to provide an ALoS.

7. May be presented in a variety of formats and locations at the discretion of

the operator. For example, they may be placed in separate columns, below

the MEL table or included in an appendix to the MEL. They may be

DATE “DRAFT” AC 91-67A

8-7

included in the “Remarks or Exceptions” column, but must be clearly

distinct from the (M) and (O) provisos.

8. Are subject to FAA review and validation to ensure they are adequate for

the relief sought.

9. May be fully depicted in the operator’s MEL or in another manual. If a

procedure is contained in another manual, the MEL should provide a

specific reference to that manual. See paragraph 8.5.6.6 below.

8.5.6.6 Reference to an FAA-Approved or FAA-Accepted Manual. An operator

may include a reference to the appropriate FAA-approved or FAA-accepted

manual that contains the procedure(s) required to address a particular MEL

item. Only FAA-approved or FAA-accepted manuals may be referenced in the

MEL. The following requirements apply when referencing these manuals:

1. Manual references must be preceded by either a proviso(s) or specific

instruction(s) defining the action required. A single proviso or specific

instruction may have more than one manual reference associated with it.

2. Manual references must direct the use of that manual, including specific

chapter, section, task, or paragraph references. The actual revision

level/date of the manual is not required in the MEL.

3. The proviso or specific instruction and manual reference in the MEL is

considered the means of compliance for MEL purposes and is

FAA-approved. The actual procedure referenced is either FAA-approved

or FAA-accepted depending on the status of the manual referenced.

8.6 Example Proviso, “As Required by 14 CFR,” and (M) and (O) Procedures.

Figures 8-1(a) through 8-4(c) demonstrate the differences between general information

contained in the MMEL “Remarks or Exceptions” column and specific

operator-developed MEL information. These are examples only and are not intended to

be used or depicted as actual MMEL or MEL procedures.

8.6.1 Example Provisos. When an MMEL contains general remarks, such as, “May be

inoperative provided procedures do not require its use,” or “May be inoperative or

missing if alternate procedures are established and used,” the operator must be specific in

the MEL.

8.6.1.1 If there are no operator procedures that rely on the item listed in the MMEL,

then the MEL may simply state, “Procedures do not require its use; may be

inoperative,” or use a similar statement.

8.6.1.2 If there are operator procedures that rely on the item listed in the MMEL, then

the MEL remark states the conditions or limitations which apply to operations

with that equipment inoperative. For example, “May be inoperative provided

overwater operations are not conducted,” or, “May be inoperative provided

long-range communications procedures do not require its use.”

DATE “DRAFT” AC 91-67A

8-8

8.6.1.3 If there are operator procedures that rely on the item listed in the MMEL, but

there is alternate equipment that could be used, then the MEL remark notes

the use of that equipment (and thus, must be operative). For example, “HDG

HOLD Mode. May be inoperative provided HDG SEL or LNAV

autopilot/flight director mode(s) is operative.”

8.6.1.4 There may be cases where the dispatch decision needs to be made by the PIC

based on conditions at the departure or destination airport, or along the route

of flight. These conditions could result from Notice to Air Missions

(NOTAM) information or ground-based equipment outages. These situations

would be known only to the pilot when preparing for specific flights;

therefore, a more general proviso would be appropriate. For example, “May

be inoperative provided departure, en route, or arrival/approach procedures do

not require its use.”

8.6.1.5 Where the MMEL contains an unconditional statement, such as, “May be

inoperative or missing,” the MEL may leave the statement unmodified, or

even omit the statement if the operator’s procedures or operations do not

require the item’s use.

8.6.2 Example “As Required by 14 CFR” Statements.

Figure 8-1(a). Example MMEL General “As Required by 14 CFR” Statement

Figure 8-1(b). Example MEL Specific “As Required by 14 CFR” Regulatory Reference

(The operator must carry the applicable 14 CFR section on board the aircraft.)

Sequence No. Item

1 2 3 4

Change

Bar

33-07

Landing Light 1 0

34. NAVIGATION

14 CFR Reference: 14 CFR 91.205(c)(4) and

91.205(d)(1).

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

DATE “DRAFT” AC 91-67A

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Figure 8-1(c). Example MEL Specific “As Required by 14 CFR” Requirement/Limitation

Sequence No. Item

1 2 3 4

Change

Bar

33-07

Landing Light 1 0

34. NAVIGATION

The landing light must be operative for

night flight operations if the aircraft is

being o

perated for hire.

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

Note: Illustrated in the examples above, the MEL will: (1) list the specific

14 CFR part and section (and the operator must carry the applicable 14 CFR

section on board the aircraft), or (2) specify the requirements and/or limitations to

conduct the flight in accordance with the appropriate 14 CFR regulations.

8.6.3 Example (M) and (O) Symbols and Procedures.

Figure 8-2(a). Example 1 MMEL General Maintenance (M) and Operations (O) Symbols

and Provisos

Sequence No. Item

1 2 3 4

Change

Bar

-30-01 Thrust Reverser C 2 0

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

78. Engine Exhaust

(M)(O) May be inoperative provided:

a) Affected thrust reverser is locked in the

forw

ard thrust position, and

b) Appropriate performance penalties are

applied.

DATE “DRAFT” AC 91-67A

8-10

Figure 8-2(b). Example 1 MEL Specific Maintenance (M) and Operations (O) Symbols

and Provisos

Sequence No. Item

1 2 3 4

Change

Bar

-30-01 Thrust Reverser 2 0

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

(M)(O) May be inoperative provided:

a) Affected thrust reverser is locked in the

forward thrust position, and

b) Appropriate performance penalties are

applied.

78. Engine Exhaust

Figure 8-2(c). Example 1 Procedures Document Maintenance (M) and Operations (O)

Procedures

78-30-01:

Maintenance (M) Procedure

Lock affected thrust reverser in the forward thrust position in accordance

with AMM 78-30-12.

Operations (O) Procedure

Refer to AFM Performance Section, Thrust Reverser inoperative for

applicable takeoff and landing penalties.

Note: AMM 78-30-12 and the AFM in the above example are FAA-approved or

FAA-accepted manuals.

DATE “DRAFT” AC 91-67A

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Figure 8-3(a). Example 2 MMEL General Maintenance (M) Symbol and Proviso

Sequence No. Item

1 2 3 4

Change

Bar

28-21-25 XBP Crossfeed Valve A 2 0

28. FUEL

(M) One or more may be inoperative in

closed position provided:

a) Al

l Booster Pumps are operative,

b) Affected XBP Crossfeed Valve is secured

in closed position, and

c) Repairs are made within 3 consecutive

calendar-days.

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

Figure 8-3(b). Example 2 MEL Specific Maintenance (M) Symbol and Proviso

Sequence No. Item

1 2 3 4

Change

Bar

28-21-25 XBP Crossfeed Valve 2 0

28. FUEL

(M) One or more may be inoperative in

closed position provided:

a) All Booster Pumps are operative,

b) Affected XBP Crossfeed Valve is secured

in closed position, and

c) Repairs are made within 3 consecutive

calendar-days.

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

DATE “DRAFT” AC 91-67A

8-12

Figure 8-3(c). Example 2 Procedures Document Maintenance (M) Procedure

28-21-25:

Maintenance (M) Procedure

CROSSFEED VALVE IN CLOSED POSITION:

1. Open the door 170AB.

2. Check that the inoperative XBP crossfeed valve (400QS/410QS) is in

close position (“C”).

NOTE: If not, set the valve to close (“C”) using the lever.

3. Disconnect the electrical connector.

4. Close the door 170AB.

NOTE: Place inoperative placard near MDU.

Figure 8-4(a). Example 3 MMEL General Operation (O) Symbol and Proviso

Sequence No. Item

1 2 3 4

Change

Bar

-43-01 B 1 0

23. COMMUNICATIONS

(O) May be inoperative provided

alternative procedures are established and

used.

Flight Deck to Ground

Interphone System

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

Figure 8-4(b). Example 3 MEL Specific Operations (O) Symbol and Proviso

Sequence No. Item

1 2 3 4

Change

Bar

-43-01 1 0

23. COMMUNICATIONS

Flight Deck to Ground

Interphone System

(O) May be inoperative provided

alternative ground communications

procedures are used.

AIRCRAFT:

(insert aircraft make and model)

TABLE KEY

XXX1. REPAIR CATEGORY

XXX2. NO. INSTALLED

XXX3. NO. REQUIRED FOR DISPATCH

XXX4. REMARKS OR EXCEPTIONS

DATE “DRAFT” AC 91-67A

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Figure 8-4(c). Example 3 Procedures Document Operations (O) Procedure

23-43-01:

Operations (O) Procedure

(O) May be inoperative provided:

1. Verify to ground crew personnel before main cabin door is closed that

ECAM message NW STRG DISC is displayed.

2. Use company hand signals as required. Refer to Ramp Operations

Manual, Chapter 1, for a complete list of company hand signals.

Note 1: The Ramp Operations Manual in the above example is an

FAA-approved or FAA-accepted manual.

Note 2: The proviso in the above MEL example was changed from the MMEL

proviso because alternative procedures “are established.”

DATE “DRAFT” AC 91-67A

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CHAPTER 9. MEL REVISIONS

9.1 General. MEL revisions may be initiated by either the FAA or the operator. The revision

to an operator’s MEL must comply with the conditions and limitations of the operator’s

MEL LOA.

• MEL revisions for an MMEL used as an MEL under LOA D095 consist of using the

latest mandatory MMEL revision and revising the procedures document, as required.

• MEL revisions for an operator-developed MEL under LOA D195 consist of revising

the operator-developed MEL.

9.1.1 Operator Responsibility to Obtain MMEL Revisions. It is the responsibility of an

operator to obtain the latest revisions to their MMEL, applicable Design Change

Approval Letter, and applicable MMEL PLs. Operators may download these documents

from the “MMELs and AED Guidance Documents” section in DRS at https://drs.faa.gov.

Note: Operators may keep informed of MMEL revisions by subscribing to

receive automatic email notifications for their aircraft. To subscribe, visit

https://service.govdelivery.com/accounts/USFAAMMEL/subscriber/new.

9.1.2 Submission of Revised Operator-Developed MEL to the FAA for Approval. Operators

must submit revisions to an operator-developed MEL under LOA D195 to the responsible

Flight Standards office for approval. An electronic copy is preferred. The revised MEL

may not be used prior to FAA approval. Holders of LOA D095 are not required to submit

a revised procedures document to the FAA.

Note: MEL revisions solely for the purpose of documenting the inapplicability of

a mandatory MMEL revision, or to incorporate revised MMEL PL-25 or PL-36

content, are not required to be submitted to the FAA.

9.2 FAA-Initiated MEL Revisions. An FAA-initiated MEL revision may be due to an

MMEL revision, MMEL PL revision, AD, or deficiencies discovered in the MEL.

9.2.1 MMEL Revision. There are two types of MMEL revisions: nonmandatory/interim, and

mandatory/standard.

9.2.1.1 Nonmandatory/Interim MMEL Revision. A nonmandatory/interim MMEL

revision means that revision to an operator’s MEL is optional and not

required. If the relief granted by the nonmandatory/interim MMEL revision is

applicable to an operator’s aircraft operations, then it is advisable the operator

revise their MEL to incorporate the MMEL revision. If the

nonmandatory/interim MMEL revision is not applicable to an operator’s

aircraft operations, they may disregard the MMEL revision altogether. For

example, a nonmandatory/interim MMEL revision is issued to provide for

optional equipment such as logo lights, which are not installed on all aircraft

of a particular type. Operators operating an aircraft without logo lights may

simply ignore the MMEL revision. Operators operating an aircraft with logo

DATE “DRAFT” AC 91-67A

9-2

lights may choose to incorporate the MMEL revision if the operator would

like MEL relief for inoperative logo lights.

1. A nonmandatory/interim MMEL revision is identified by the current

standard revision number plus a lowercase letter. For example, a

nonmandatory/interim revision following revision 5 will be identified as

revision 5a. There may be subsequent interim revisions to the same

standard revision. These subsequent revisions carry the next lowercase

letter (e.g., 5b, 5c, or 5d).

2. The operator’s MEL revision number does not have to match the MMEL

revision number. Operators may use their own revision numbering system.

3. If an MMEL revision results in a change to the system number or

sequence item number, the operator does not need to modify or close an

open MEL item and reinitiate it under its new number. Instead, the item

may continue to be tracked under its original item number until the item is

repaired and the deferral cleared.

9.2.1.2 Mandatory/Standard MMEL Revision. A mandatory/standard MMEL

revision means that revision to an operator’s MEL is required. A

mandatory/standard MMEL revision includes changes applicable to all

operators using an MEL for a specific aircraft type.

9.2.1.2.1 A mandatory/standard MMEL revision is identified by the next successive

change to the basic MMEL revision number. For example, the next

mandatory/standard revision following nonmandatory/interim revision 6a, 6b,

or 6c is revision 7. The next mandatory/standard revision following revision 7

is revision 8.

9.2.1.2.2 The operator is required to review the mandatory/standard MMEL revision to

determine if the more restrictive revised content is applicable to their aircraft

and operation. If so, the operator must revise their MEL as follows:

1. For an MMEL used as an MEL under LOA D095: Within

90 calendar-days of the date of the MMEL revision, the operator must

revise their procedures document. The revision must address (M) and (O)

or “as required by 14 CFR” procedures, as applicable. If no changes are

determined to be applicable to the aircraft or operator, then the operator is

not required to update the procedures document. However, the FAA

recommends the operator make a statement in the procedures document

that the mandatory revision has been reviewed and determined not to

apply. Regardless, the procedures document must contain the MMEL

revision number on which the MEL is based.

2. For an operator-developed MEL under LOA D195:

a. If the revised content of the mandatory/standard MMEL revision is

applicable, the operator must revise their MEL and incorporate

DATE “DRAFT” AC 91-67A

9-3

applicable changes and submit it to the responsible Flight Standards

office for approval within 90 calendar-days of the date of the MMEL

revision. The revised MEL may not be used prior to FAA approval.

b. If the revised content of the mandatory/standard MMEL revision is not

applicable, within 90 calendar-days of the revision, the operator must

document its inapplicability. Revise the MEL control page(s) or LEP

to indicate the MEL is in compliance with the required MMEL

revision. The operator will retain the previous FAA-signed MEL

control page(s) or LEP within the MEL.

c. Irrespective of applicability, the operator-developed MEL must

contain the MMEL revision number on which the MEL is based.

9.2.1.2.3 If an MMEL revision results in a more restrictive proviso, the operator does

not have to close and reinitiate an existing open MEL item affected by the

revision. Existing MEL items may remain open in accordance with the

original proviso under which the item was initially deferred until such time as

the item is repaired or replaced and the MEL item is closed.

9.2.1.2.4 If an MMEL revision results in a change to the system number or sequence

item number, the operator does not need to modify or close an open MEL item

and reinitiate it under its new number. Instead, the item may continue to be

tracked under its original item number until the item is repaired and the

deferral cleared.

9.2.2 Revisions as a Result of an MMEL PL with a GC Designation. An operator may revise

their MEL based on relief available in an MMEL PL with a current GC designation. An

operator is not required to include GC designation relief in their MEL. See paragraph 2.6

above for detailed information on MMEL PLs with a GC designation.

9.2.3 Revisions Initiated by the Responsible Flight Standards Office. The responsible Flight

Standards office may initiate an MEL revision for reasons such as the issuance of an AD,

upon discovery of deficiencies in the operator’s MEL (including (M) and (O)

procedures), or upon discovery that the operator has modified their aircraft.

9.2.3.1 The responsible Flight Standards office will inform the operator of the need to

revise their MEL in writing and provide the reasons why the revision must be

accomplished.

9.2.3.2 The responsible Flight Standards office will allow the operator

90 calendar-days to complete the revision process. An operator may request

an extension for developing an MEL revision. If the responsible Flight

Standards office determines the safety of flight could be affected (e.g., AD),

they may specify a shorter period of time.

9.2.4 MMEL PL-25 (Definitions) or MMEL PL-36 (Preamble) Revision. A revision to MMEL

PL-25 does not require revision of the operator’s MEL. However, the current revision to

MMEL PL-25 should be incorporated in the next FAA or operator-initiated MEL

DATE “DRAFT” AC 91-67A

9-4

revision. A revision to MMEL PL-36 will require a revision to a procedures document

under LOA D095 or an operator-developed MEL under LOA D195. MEL revisions

solely for the purpose of incorporating revised MMEL PL-25 or PL-36 content, are not

required to be submitted to the FAA.

9.3 Operator-Initiated MEL Revisions. An operator may revise their MEL for a number of

reasons. An operator-initiated MEL revision will not be, in any way, less restrictive than

the MMEL.

9.3.1 Major Aircraft Modifications. An operator may elect to initiate an MEL revision due to

major aircraft modifications, such as an STC, a major alteration (refer to FAA Form 337),

or a modification to the TC.

9.3.2 Installation of Additional Items. An operator may initiate a change based on the

installation of additional items. An operator may add an item to their MEL only if it is

listed in:

1. The MMEL,

2. An applicable Design Change Approval Letter (e.g., STC Relief Approval Letter), or

3. An applicable MMEL PL with a current CG designation.

Note: See Chapter 10 for information on how to obtain relief for an item not

listed in items 1–3 above.

9.3.3 Changes in Operational Complexity. An operator may need to revise their MEL due to

changes in their operational complexity, such as adding a type of operation

(e.g., Reduced Vertical Separation Minimum (RVSM), CAT II/III landing minimums,

etc.). An operator may need to revise their MEL for the purpose of adding or revising (M)

and (O) procedures based on operational complexity.

9.4 Vertical Bar (Change Bar). A vertical bar denotes a change in content. For MMELs, a

vertical bar is placed in the right margin; location in the operator’s MEL is a matter of

choice. A change due to copy editing (e.g., punctuation, spelling, or grammatical

structure) does not need a vertical bar in an MMEL or MEL. All vertical bars applicable

to the previous revision of the MMEL are removed at the next revision. It is permissible

to issue an MMEL or MEL revision without vertical bars when the revision affects most

or all relief items. In which case, in lieu of vertical bars, a note is added to the

“Highlights of Change” page instructing operators to consider all content revised and

indicating that vertical bars are not used. Other alternate means of compliance may be

used if approved by the Administrator.

DATE “DRAFT” AC 91-67A

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CHAPTER 10. MEL RELIEF FOR ITEMS INSTALLED AFTER TYPE

CERTIFICATION

10.1 General. The aircraft design approval holder (DAH) determines the configuration of the

aircraft, the items installed, and the official parts listed during the initial aircraft type

certification process conducted at the time of manufacture. Any subsequent installation or

removal of items may be accomplished only through a STC, an Engineering Order (EO),

a field approval, or other FAA-approved methods (as appropriate).

10.2 Operator NEF Items or Administrative Control Items (ACI). Items listed on an

operator’s NEF program and ACIs are excluded from the requirements for evaluation, as

listed in this chapter.

10.3 MMEL Items and MEL Items. For an item to be listed in an operator’s MEL, it should

first be listed in the MMEL, as the MMEL is the basis for an operator’s MEL. (The only

exception to this policy would be MEL relief added through an MMEL PL with a GC

designation or an AED approval letter, as these are considered addendums to the

MMEL.)

10.3.1 Example of This Concept. If an operator is wanting to add an item to its MEL, such as a

flight management system (FMS) or an autopilot, that item should first appear in the

applicable aircraft’s MMEL as “FMS” or “Autopilot.”

10.3.2 Items Not Listed in an MMEL. An operator may petition the AED to add items to the

applicable aircraft’s MMEL through the FOEB process. This may be accomplished

through the operator’s responsible Flight Standards office or directly to the responsible

AED office. An operator should be prepared to provide the information needed by the

FOEB for this evaluation. See the list of needed items found in paragraph 10.7 below.

10.4 MMEL PL-109. MMEL PL-109, Supplemental Type Certificate (STC) MMEL/MEL

Relief, contains policy specific to MEL relief for items installed by STC and other design

changes.

10.5 STCs. A design change to a TC is often done with an STC. Ideally, MMEL/MEL relief

can be evaluated during the certification of the STC when this is requested by the STC

applicant.

10.5.1 Evaluation of MEL Relief During STC Certification. To obtain MMEL/MEL relief, the

STC applicant involved in the certification of an STC should submit a request for relief in

accordance with the FOEB MMEL Agenda Coordination Process (refer to FAA

Order 8900.1, Volume 8, Chapter 2, Section 3, Flight Operations Evaluation Board, and

AC 21-40, Guide for Obtaining a Supplemental Type Certificate). This submission

should be made early in the certification process to allow MMEL/MEL evaluation

concurrent with the certification process. Requests for relief subsequent to the completion

of the certification process can delay the availability of MMEL/MEL relief for an item.

10.5.2 MEL Relief After STC Certification. STCs issued without concurrent AED evaluation

may be granted relief by request from the operator to the FAA. STCs already listed by

DATE “DRAFT” AC 91-67A

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STC number in the applicable aircraft MMEL, or in an AED approval letter, may be

added to the operator’s MEL through the normal revision process without further

evaluation. However, a PI may coordinate with the AED during this process, as needed.

10.6 Adding Relief for Items Installed After Type Certification. Using the normal revision

process found in Chapter 9, an operator may add relief for items to its MEL through any

of the following solutions listed below.

10.6.1 MMEL Specifically Lists the Relief. Where the MMEL lists the specific STC number

(e.g., ST00733SE) or identifies the specific design change nomenclature (other than

STCs), an operator may add the relief to its MEL.

10.6.2 Design Change Approval Letters. Upon evaluation and approval of a design change, the

AED will submit an approval letter directly to the FAA’s DRS. Operators may download

Design Change Approval Letters from the “MMELs and AED Guidance Documents”

section in DRS at https://drs.faa.gov. The approval letter will contain the allowed relief,

including conditions and provisos, along with remarks or exceptions. Approval letters

will be dated and have revision numbers. Operators may amend their MEL(s) with the

relief for the STC(s) in accordance with the AED approval letter. Paper copies of the

AED approval letter are also acceptable in lieu of the DRS database.

10.6.3 MEL Relief Through MMEL PL With GC Designation. Operators may add relief into

their MEL(s) for an STC through an MMEL PL with a current GC designation. However,

upon AED evaluation of the item (if an evaluation is conducted), operators may have to

amend or remove previously approved relief in their MEL(s). See Chapter 2 for

additional information on GC.

10.6.4 Responsible Flight Standards Office’s Evaluation of the Relief. If the proposed relief is

not covered by one of the three solutions immediately above, the item may be evaluated

by the responsible Flight Standards office. To add MEL relief using this method, the

following points should be considered:

1. The basic item needs to be found in the applicable aircraft’s MMEL (e.g., FMS,

autopilot, and passenger seat). If not, the AED must complete the evaluation.

2. The operator’s Safety Management System (SMS) (as applicable) reveals that the

proposed relief does not present a hazard to the operator’s use of the relief.

3. The PIs conducting the evaluation may consult with the STC holder, AED, OEM, and

other stakeholders during their evaluation of the operator’s proposal.

4. If the item was previously evaluated by the AED and relief was not granted, the item

is not eligible for evaluation by the responsible Flight Standards office.

5. If the PI believes a hazard exists with the operator’s proposal, the item is not eligible

for relief.

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10.7 Items Needed for Evaluation of Design Changes. Each proposed MEL item should

have accompanying supporting justification before it will be considered. The information

needed by the FAA allows a thorough evaluation of the risk associated with operating the

aircraft with the item inoperative. The FAA may reject an item proposal if the

justification information is inadequate. At a minimum, the following information should

accompany all item proposals:

1. The title and number of the proposed MMEL item;

2. A brief description of the system and its intended functions;

3. A summary of the proposed MMEL relief;

4. A brief description of intent;

5. The effect of dispatching a flight with this inoperative item;

6. The operating rule(s) that require(s) the item to be operative, as applicable;

7. The transfer of function when the item is inoperative;

8. The next most critical failure;

9. The effect on increased flightcrew workloads (including risk mitigations);

10. The certification requirements for the item;

11. Any conflicts with AFM limitations, procedures, or AD;

12. If the item affects or is required to accomplish an emergency procedure;

13. The effect on aircraft capability in an emergency;

14. (M) and (O) procedures required for the proposed dispatch condition;

15. Any information that adds support to the proposal (e.g., wiring diagrams, schematic

drawings, or STC documents); and

16. Any other information requested by the FAA before or during the evaluation.

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CHAPTER 11. NONESSENTIAL EQUIPMENT AND FURNISHINGS (NEF)

PROGRAM

11.1 Definition. NEF are those items installed on the aircraft as part of the original TC, STC,

EO, or other form of alteration that have no effect on the safe operation of flight and

would not be required by the applicable certification or operational rules. These are items

that, if inoperative, damaged, or missing, have no effect on the aircraft’s ability to be

operated safely under all operational conditions. NEF items are not items already

identified in the MEL or CDL of the aircraft. NEF do not include items that are

functionally required to meet the certification rule or for compliance with any operational

rule.

11.2 Background. The NEF program originated from an earlier form called Passenger

Convenience Items (PCI) program. PCIs were items related to passenger convenience,

comfort, or entertainment located in the passenger compartment, galley, and lavatory

areas. The PCI program did not allow for nonessential items that were missing or

inoperative located elsewhere in the aircraft. Due to the limited nature of PCI, the FAA

replaced the PCI title in ATA/JASC code 25 in all MMELs with the acronym NEF. An

NEF program allows operators to use the deferral authority granted by virtue of their

MEL LOA to provide deferral relief for nonessential items located throughout the

aircraft.

11.3 The NEF Program Under § 91.213(a). An operator’s MEL approved under the

provisions of § 91.213(a) may include an NEF program that allows relief for nonessential

items. An NEF program is supplemental to the MEL approval under § 91.213(a); it is not

a stand-alone program. An NEF program is developed by an operator to meet their

individual needs. An operator’s NEF program is a supplement to the operator’s MEL.

The NEF program encompasses: (1) an (optional) list of NEF items located in the

operator’s MEL, (2) a process for evaluating an item in accordance with NEF

requirements, and (3) policies and procedures for repair and/or replacement. Operators

may choose to use the recommended method of evaluation shown in Figure 11-2, NEF

Item Selection Criteria Elements Flowchart, or they may use an alternative method that is

acceptable to the FAA. If an operator’s NEF program is insufficient or systemically

problematic, the FAA may cancel, rescind, or revoke the operator’s MEL LOA.

11.3.1 NEF items are:

• Items installed on the aircraft that have no effect on the safe operation of the aircraft.

• Items installed as part of the original TC, STC, EO, or other form of alteration, not

required by certification or operational rules.

• Items that if inoperative, damaged, or missing, have no effect on the safe operation of

the aircraft under all operational conditions.

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11-2

• Nonessential items located throughout the aircraft, including the flight deck area,

service areas, cargo areas, and crew rest areas, in addition to the passenger

compartment, lavatories, and galley areas.

• Cosmetic items not associated with an MEL or CDL item.

Note: Cosmetic items may have associated fire retardant/blocking requirements to

be considered before listing them as an NEF item.

11.3.2 NEF items are not:

• Instrument and equipment already identified in the MMEL, MEL, or CDL of the

applicable aircraft.

• Instruments and equipment functionally required for meeting any certification rule.

• Instruments and equipment required for compliance with any operational rule.

• Items deferred contrary to an operator’s Continuous Airworthiness Maintenance

Program (CAMP).

• Paint (mismatched, bad, or worn condition).

• Paint is addressed in other maintenance documents utilized for determining

airworthiness; the NEF program is not applicable.

• Rodent or pest (bug) infestations of any type.

• Items which are only dirty or soiled (e.g., carpet, seats, interior sidewalls, dirty

garbage can, etc.).

Note: An NEF item is not to be used as an ACI. An ACI is listed in the MEL for

tracking and informational purposes. (Refer to MMEL PL-25 for more

information regarding ACIs.)

11.4 Deferral Authority. Authority for an operator’s NEF program is inherent in their MEL

LOA; therefore, the NEF program does not need to be submitted to the FAA with the

operator’s MEL LOA application. An operator may defer NEF items in accordance with

their operator-developed NEF program.

11.4.1 Although the NEF program is included in ATA/JASC chapter 25, it may address items

that fall under other ATA/JASC chapters.

11.4.2 The operator’s NEF deferral procedures and processes may not provide for deferral of

items within serviceable limits identified in the manufacturer’s maintenance manual,

Structural Repair Manual (SRM), ADs, or operator’s maintenance program

(e.g., CAMP).

11.4.3 NEF items are deferred under the operator’s NEF program, not under the authority of an

Airframe and Powerplant (A&P) certificate.

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11.5 NEF Program Development. Operators develop, implement, maintain, and revise their

NEF program. The NEF program provides for the ability to defer NEF items whose

failure would otherwise result in a non-airworthy status until repair (or replacement) of

an item not affecting safety of flight. The FAA may conduct surveillance on an operator’s

NEF program at any time. An operator’s failure to comply with their NEF program may

result in the cancellation, rescission, or revocation of the operator’s MEL LOA.

11.6 Required NEF Program Contents. Operators will design their NEF program to fit the

scope and depth of operation, including, at a minimum, the following nine processes and

procedures:

11.6.1 Method of Tracking NEF Items. A list or other equivalent method of tracking NEF items

may be used. Although an operator does not need to develop and maintain a list, nor

include the specific NEF items inside the MEL, a list reduces both the FAA and

operator’s time spent analyzing recurring deferrals of the same item. Operators who

choose not to develop an NEF list will be required to treat each NEF deferral as a newly

discovered NEF item, as outlined in their individual NEF program.

11.6.1.1 If used, the NEF item list should be comprehensive but may be listed in

general terms. For example, “cosmetic trim-strips” may be listed rather than

identifying each strip individually on the NEF item list.

11.6.1.2 Operators are not required to submit changes to their NEF item list to the

FAA, and the FAA is not required to review changes to the list.

11.6.1.3 The NEF item list does not have to be part of the MEL and may be kept in a

form and manner determined by the operator.

11.6.1.4 Whether in paper or electronic format, the applicable portions of the NEF item

list and NEF process must be available to the flight and cabin crews,

maintenance, and flight operations personnel, as appropriate, when items are

being deferred in accordance with the operator’s NEF program.

11.6.2 Identifying Deferrals. Procedures and processes for identifying NEF items that may be

deferred.

11.6.3 Tracking Deferrals. Procedures for tracking program deferrals.

11.6.4 Documentation Procedures. Documentation procedures for inoperative, damaged, or

missing NEF items.

11.6.5 (M) and (O) Procedures. Appropriate (M) and (O) procedures.

11.6.6 Follow-Up Maintenance. Procedures for follow-up maintenance, repair, and replacement.

11.6.7 Repair Intervals. Repair intervals are prescribed for NEF items. Operators may use the

current MEL deferral categories at their discretion or an alternate method acceptable to

the Administrator.

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11-4

11.6.8 Title 14 CFR Part 43, § 43.13 Compliance. Any portions of an NEF program that

reference maintenance or a maintenance procedure must comply with acceptable

practices, as set forth in § 43.13.

11.6.9 NEF Proviso. The following proviso to an NEF program (see Figure 11-1 below) is

included in the operator-developed MEL ATA/JASC chapter 25, or in the case of an

MMEL used as an MEL, included in the procedures document. The reference proviso

must be copied verbatim. However, as indicated in the proviso, the aircraft operator’s

manual where the NEF program is found will contain specific processes and procedures.

Figure 11-1. Required NEF MEL Proviso for an Operator’s NEF Program

System & Sequence

Numbers

25 Equipment/

Furnishings

Repair

Interval

Number

Installed

Number

Required

for

Dispatch

Remarks or Exceptions

Nonessential

Equipment and

Furnishings (NEF)

May be inoperative, damaged, or

missing provided that the item(s) is

deferred in accordance with the NEF

deferral program. The NEF program,

procedures, and processes are

outlined in the operator’s [insert

name] Manual. (M) and (O)

procedures, if required, must be

available to the flightcrew and

included in the aircraft operator’s

appropriate document.

NOTE: Exterior lavatory door

ash trays are not considered NEF

items.

11.7 NEF Program Approval. An operator is not required to submit their NEF program, or

NEF program revisions, to the FAA, and the FAA is not required to review it. However,

the FAA may conduct surveillance on an operator’s NEF program at any time.

11.8 Criteria for Selection of NEF Items. NEF items are not safety-of-flight items. They

have not been evaluated by the FAA through the normal AED review process. Therefore,

before an operator can list an item as being deferrable under the NEF program, they will

follow their NEF program procedures. When reviewing items for inclusion in an

operator’s NEF item list, operators should ask the following questions:

• Is the item required for the operational rules in which the aircraft is operated?

• Does the item create the potential for fire/smoke or other hazardous condition?

• Could the item have an adverse effect on other required systems or components?

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• Does the item’s condition potentially affect the safety of passengers, crew, or service

personnel?

• Could the item have a negative impact on emergency or abnormal procedures?

• Does the item create an additional workload for the crew at critical times of flight or

flight preparation?

• Does the flightcrew need to evaluate the deferred NEF item on a flight-by-flight

basis?

11.9 NEF Deferral Process. See Figure 11-2 for a flowchart that includes the following

elements in sequence. The flowchart is a guide for developing an NEF deferral process.

The process may be modified to facilitate inclusion in an operator’s overall MEL deferral

program with the intent of the elements outlined in the flowchart below being addressed.

11.9.1 Documentation. For an inoperative, damaged, or missing item to be considered for

inclusion in an NEF program, the discrepancy will be documented in the aircraft logbook

(or other approved location) per the operator’s discrepancy reporting system. This action

is completed by the flightcrew, company maintenance personnel, or personnel authorized

and approved to perform such functions as outlined in the operator’s maintenance

program.

11.9.2 Current NEF Items. If the inoperative, damaged, or missing item is already on the NEF

item list (if used), the established procedures for NEF deferral of the item will be

followed.

11.9.3 MMEL, CDL, or MEL Items. An MMEL, CDL, or MEL item may not be deferred in

accordance with the operator’s NEF program. The operator must follow the deferral

procedures for inoperative, damaged, or missing items listed in the MMEL, MEL, or

CDL, as per § 91.213(a)(5).

11.9.4 Subcomponents of MMEL, CDL, or MEL Items. If the inoperative, damaged, or missing

item is a subcomponent of a system identified in the MMEL/MEL/CDL, where no

previous relief was authorized, the subcomponent may not be deferred in accordance with

the operator’s NEF program.

11.9.5 Required by Certification or Operational Rules. If the item is required by any applicable

certification or operational rules, the item may not be deferred in accordance with the

operator’s NEF program.

11.9.6 Safety-of-Flight Issues. If it is evident from a maintenance or operational perspective that

an item could have an adverse effect on safety of flight; or if there is a safety of flight

issue with an inoperative, damaged, or missing item, that item may not be deferred.

11.9.7 Source (Underlying Cause). If the presence of a safety-of-flight issue is unknown, not

present, or not applicable, ascertain whether the source or root cause for the item can be

identified. If the source or root cause cannot be identified or isolated, that item may not

be deferred in accordance with the operator’s NEF program.

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11.9.8 Effects on Equivalent Level of Safety (ELOS). If the item has no impact on safety of

flight, that item may be deferred in accordance with the operator’s NEF program.

11.9.9 Isolated with Applicable Maintenance Procedures. If the item can be isolated and

re-evaluated using applicable maintenance procedures and a determination made that

there is no safety of flight concern, it may be deferred in accordance with the operator’s

NEF program.

11.9.10 Defer in Accordance with the Operator’s NEF Program.

11.9.11 Update the NEF Item List, as Required.

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Figure 11-2. NEF Item Selection Criteria Elements Flowchart

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CHAPTER 12. CONFIGURATION DEVIATION LIST (CDL)

12.1 Purpose of the CDL. The CDL is a list of externally exposed nonstructural aircraft parts

that may be missing and is tailored for each model aircraft. The CDL evolved over

several years from what was commonly known as a “missing parts list,” which was a list

of nonstructural external parts of an aircraft that were found missing after flight. The

missing parts list is known today as the CDL. A CDL allows continued operation with

missing externally exposed nonstructural parts by defining restrictions, limitations, or

performance penalties, while the aircraft remains airworthy.

12.2 Development. The aircraft manufacturer develops a CDL during the initial certification

process. This is not a requirement for aircraft certification. The manufacturer makes the

decision to develop or not to develop a CDL. The responsible Aircraft Certification

Service office has final approval of all FAA-approved CDLs and all requests for

revisions to an FAA-approved CDL.

12.2.1 Which Aircraft Has a CDL. A CDL is developed for most U.S.-built transport category

part 25 aircraft and many part 23 aircraft by aircraft manufacturers during the initial

certification process. However, they are not a required element for aircraft certification.

The manufacturer makes the decision to develop or not to develop a CDL. If deemed

necessary, the aircraft manufacturer develops a proposed CDL and coordinates

submission with the responsible Aircraft Certification Service office and the AED. The

responsible Aircraft Certification Service office and AED review, evaluate, and may

conduct or oversee any required testing and data collection necessary to approve

proposed CDL items. Approval of a CDL is by the responsible Aircraft Certification

Service office or through an OEM Organization Designation Authorization (ODA)

program.

12.2.2 U.S.-Manufactured Aircraft. For U.S.-manufactured aircraft, an FAA-approved CDL is

either:

• Incorporated into the limitations section of the AFM,

• Published as an appendix to the AFM, or

• Published as a supplement to the AFM.

12.2.3 Aircraft Manufactured Outside the United States. The CDL may be a standalone

document that is part of the SRM or another manufacturer’s document.

12.3 CDL Versus MEL. An MEL and a CDL are separate documents. An MEL is approved

by the responsible Flight Standards office. A CDL is approved by the responsible Aircraft

Certification Service office, or through an OEM’s ODA program. An MEL and a CDL

may be kept in the same binder but will be clearly partitioned as two separate

“stand-alone” documents. If an operator desires an amendment to the CDL, the request

should be made to the responsible Aircraft Certification Service office, or directly to the

aircraft manufacturer.

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12.4 CDL Management Program. Operators will ensure they comply with all penalties,

limitations, and restrictions associated with a CDL. An operator may develop procedures

more restrictive than the CDL. An operator is not required to have a CDL management

program. If an operator chooses to develop a CDL management program, they are not

required to submit it to the FAA, and the FAA is not required to review it.