U.S . Department of Transportation Federal Aviation Administration Advisory Circular Subject: Development and Use of an Operator’s MEL, NEF Program, and CDL for Operations Under 14 CFR Parts 91K, 121, 125, and 135 Date: 11/1/23 AC No: 120-125 Initiated by: AFS-200 Change:
This advisory circular (AC) provides information for operator development and use of a minimum equipment list (MEL), MEL management program, nonessential equipment and furnishings (NEF) program, and Configuration Deviation List (CDL). This AC applies to all operators subject to Title 14 of the Code of Federal Regulations (14 CFR) parts 91 subpart K (part 91K), 121, 125, and 135. The use of an MEL should only be authorized through the issuance of Operations Specification (OpSpec) or Management Specification (MSpec) D095, Minimum Equipment List (MEL) Authorization, as appropriate. This AC does not address operations conducted under part 91, § 91.213 with inoperative instruments or equipment without an MEL.
This AC describes an acceptable means, but not the only means, for an operator to develop and use t heir MEL, NEF, and CDL in accordance with regulatory requirements and Federal Aviation Administration (FAA) policy. 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.
Wesl ey L. Mooty Acting Deputy Executive Director, Flight Standards Service
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CONTENTS Paragraph Page
Chapter 1. Introduction1-1
1.1 P urpose of This Advisory Circular (AC)1-1
1.2 Audience1-1
1.3 Where You Can Find This AC1-1
1.4 B ackground1-1
1.5 Nonessential Equipment and Furnishings ( NEF) Program1-2
1.6 Configuration Deviation List (CDL)1-2
1.7 Terminology1-2
1.8 Regulatory Requirements1-8
1.9 O pSpec/MSp ec D095 Requirements1-9
1.10 Foreign Air Carriers and Foreign Operators of U.S.-Registered Aircraft
Engaged in Common Carriage (14 CFR Part 129)1-9
1.11 AC Feedback Form1-9
Chapter 2. M inimum Equipment List (MEL)—General2-1
2.1 G eneral2-1
2.2 Categories of MEL Items2-1
2.3 Limitations of MEL Deferrals2-1
2.4 Required Sections2-2
2.5 Optional Sections2-3
Chapter 3. M inimum Equipment List (MEL)—Content3-1
3.1 M EL Contents3-1
3.2 Air Transport Association of America (ATA) or Joint Aircraft
System/Component (JASC) Coded Sections3-1
3.3 Repair Categories3-2
3.4
Number of Items Installed3-2
3.5 Number Required for Dispatch3-3
3.6 Remarks or Exceptions3-3
3.7 MEL Remarks and Exceptions Defined3-4
3.8 MEL Proviso Stipulations Should Be Specific3-4
3.9 (M) and (O) Procedures3-4
3.10 Provisos3-5
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3.11 Notes3-5
3.12 Definitions3-6
3.13 References3-6
3.14 Specific 14 CFR Requirements3-7
Chapter 4. M EL Relief for Items Installed After Type Certification4-1
4.1 G eneral4-1
4.2 Operator NEF Items or Administrative Control Items (ACI)4-1
4.3 MMEL Items and MEL Items4-1
4.4 STC4-1
4.5 Adding Relief for Items Installed After Type Certification4-2
4.6 Items Needed for Evaluation of Design Changes4-3
Chapter 5. MEL Management Program Requirements5-1
5.1 G eneral5-1
5.2 MEL Management Program5-1
5.3 Continuing Authorization—Single Extension5-1
5.4 Additional Extensions5-2
Chapter 6. Conducting Operations Utilizing MEL Relief6-1
6.1 G eneral.6-1
6.2 Operational Requirements6-1
6.3 Dispatch or Flight Release Requirements6-2
6.4 Multiple Inoperative Items or System Components6-3
6.5 Availability of the MEL to Operator Personnel6-4
Chapter 7. MEL Creation and Formatting7-1
7.1 G eneral7-1
7.2 M EL Format Outline7-1
7.3 Prohibited Items7-3
7.4 MEL Restrictions7-3
7.5 Fleet MELs7-3
Chapter 8. FAA Review and Initial Approval of an Operator’s MEL8-1
8.1 General8-1
8.2 Preliminary8-1
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8.3 Submission8-1
8.4 Review and Findings of an Operator’s MEL Submission8-2
8.5 MEL Management Program Review8-3
8.6 Correction of Deficiencies8-4
8.7 Approval and Issuance of OpSpec/MSpec D0958-4
Chapter 9. MEL Revisions9-1
9.1 G eneral9-1
9.2 FAA-Initiated Revisions9-1
Figur e 9- 1. Example Global Change Header Box9-3
9.3 O perator- Initiated Revisions9-3
Chapter 10. Nonessential Equipment and Furnishings (NEF) Program10-1
10.1 B ackground10-1
10.2 General10-1
10.3 D eferral Authority10-2
10.4 NEF Program Development10-2
10.5 Required NEF Program Contents10-2
F igure 10-1. Required NEF MEL Proviso for an FAA-Approved NEF Program10-4
10.6 N EF Program Approval10-4
10.7 NEF Program Revisions10-5
10.8 Criteria for Selection of NEF Items10-5
F igure 10- 2. NEF Item Selection Criteria Elements Flowchart10-7
Chapter 11. Configuration Deviation List (CDL)11-1
11.1 P urpose of the CDL11-1
11.2 D evelopment11-1
11.3 Operator Use of the CDL11-1
11.4 Operator’s Manual11-2
11.5 CDL Item Recording and Notifications11-2
1-1 CHAPTER 1. INTRODUCTION
1.1 Purpose of This Advisory Circular (AC). This AC provides clarity on minimum equipment list (MEL), nonessential equipment and furnishings (NEF) program, Configuration Deviation List (CDL), and certain Federal Aviation Administration (FAA) requirements regarding the operation of aircraft with inoperative instruments and equipment.
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.
1.2 Audience. This AC applies to all operators under Title 14 of the Code of Federal Regulations (14 CFR) parts 91 subpart K (part 91K), 121, 125, and 135.
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 Background. An aircraft’s airworthiness certificate is based on it conforming to its type certificate (TC) and being in a condition for safe operation. While items installed in an aircraft have to be operative for the aircraft to meet TC requirements, an approved MEL allows an operator to operate the aircraft with certain inoperative items for a limited, defined period. An approved MEL, as authorized by the operations specification (OpSpec)/management specification (MSpec), constitutes an approved change to the type design without requiring recertification.
1.4.1 Under part 91, § 91.7, an operator cannot operate an aircraft unless it is in an airworthy condition. To be airworthy under § 91.213, the aircraft must comply with the TC and be in a condition for safe operation. To operate an aircraft with an inoperative instrument or equipment violates § 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 MEL criteria is necessary when taking advantage of the relief that an MEL provides; in the absence of such compliance, the aircraft is not airworthy.
1.4.2 The FAA developed the MEL concept after it recognized that, under certain circumstances, a flight or series of flights might occur safely with certain inoperable instruments and equipment. In certain situations, an Acceptable Level of Safety (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 requirement to have an operable landing light.
1.4.3 All articles, commonly referred to as items, related to aircraft airworthiness that are not included in an approved MEL are required under § 91.213 to be operative in accordance
1-2 with the aircraft’s TC. An MEL does not include obviously required items, such as wings, rudders, flaps, engines, landing gear, etc.
1.4.4 The MEL requirements and related processes are independent from an aircraft’s operating requirements and an MEL cannot authorize a deviation from operating rules.
An aircraft is not airworthy when any item that is not included in the MEL is inoperative.
1.4.5 The MEL is not intended to enable the continued operation of the aircraft with inoperative items for an indefinite period of time. The MEL’s basic purpose is to allow limited operations of aircraft with inoperative equipment within the framework of a well-defined program. This program should be proactively managed by the operator and should ensure that repairs are made as soon as practicable to avoid further operational impact.
1.4.6 An MEL is developed by the operator for their particular operations (e.g., parts 91K, 121, 125, and/or 135). An MEL is typically developed from a Master Minimum Equipment List (MMEL) for the aircraft type. The operator uses the MMEL as the baseline to develop the MEL and the operational and maintenance procedures. The MEL lists the items installed in the operator’s aircraft and is submitted to the responsible FAA Flight Standards office.
1.5 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 an operator to operate an aircraft without the use of nonessential items based on the approved OpSpec/MSpec. See Chapter 10, Nonessential Equipment and Furnishings (NEF) Program, for additional information on NEF programs.
1.6 C onfiguration 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 externally exposed nonstructural parts by defining restrictions, limitations, or performance penalties, while the aircraft remains airworthy. See Chapter 11, Configuration Deviation List (CDL), for additional information on the CDL.
1.7 T erminology.
1.7.1 A ir Transport Association of America (ATA) . The use of the term “ATA coded sections” refers to the ATA codes, which were first published in 1956 as a standardized numbering system for aircraft systems. ATA changed its name to “Airlines for America” (A4A) in 2011, but the acronym “ATA” is still used for coded aircraft systems. The acronyms “ATA” and “A4A” are interchangeable.
1.7.2 Administrative Control Item (ACI). An ACI is an item that is not contained in the MMEL, but that may be included in the operator’s MEL for tracking and informational purposes only. For example, an ACI may be used to track the accomplishment of required auxiliary power unit (APU) cold-soak, or in-flight verification starts for Extended Operations (ETOPS) aircraft. See Chapter 2, Minimum Equipment List (MEL)—General, for additional information regarding ACI.
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1.7.3 Aircraft Evaluation Division (AED). FAA AED inspectors serve as the FAA Flight Standards Service (FS) technical subject matter experts (SME) for operational and engineering activities. They coordinate and assist with aircraft certification and continued airworthiness programs and serve as a liaison with the responsible Aircraft Certification Service office during an aircraft’s initial certification and throughout its service life.
1.7.4 A irplane Flight Manual (AFM)/Rotorcraft Flight Manual (RFM) or Pilot’s Operating Handbook (POH). The FAA-approved AFM/RFM (or POH) is an FAA-approved document that contains information (e.g., operating limitations, operating procedures, performance information, etc.) necessary to operate the aircraft (airplane or rotorcraft, as appropriate) at the level of safety established by the aircraft’s certification basis. It is approved by the responsible Aircraft Certification Service office during type certification.
The approved flight manual for the specific aircraft is listed on the applicable Type Certificate Data Sheet (TCDS). The approved flight manual is the governing document for operational limitations and performance parameters for an aircraft. The term “approved flight manual” can apply to an AFM/RFM (or POH). The FAA requires an approved flight manual for aircraft type certification. Refer to 14 CFR part 21, § 21.5;
part 23, § 23.2620; part 25, § 25.1581; part 27, § 27.1581; and part 29, § 29.1581. The applicable document (AFM, RFM, or POH) should be indicated in the aircraft operator’s MEL when applicable.
1.7.5 C onfiguration Deviation List (CDL). A CDL is a list of exposed (external) aircraft parts that may be missing for flight under specific conditions and limitations. CDLs are developed by aircraft manufacturers for each specific model and approved by the FAA.
1.7.6 C onsidered Inoperative. The phrase “Considered Inoperative,” as used in the “Remarks or Exceptions” column, means an item should be treated for dispatch, taxi with intent for flight, and flight purposes as though it were inoperative. “Inoperative” refers to the malfunction of an item to the extent that it does not accomplish its intended purpose or is not consistently functioning normally within its approved operating limit(s) or tolerance(s), or both. The item will not be used or operated until the original deferred item is repaired. Additional actions include documenting the item on the dispatch release (if applicable); placarding; complying with all remarks or exceptions, including any maintenance and operations procedures; considering applicable notes; and observing the repair category.
1.7.7 D ash ( -). A dash indicates a variable number (quantity) of items may be installed or required for dispatch.
1.7.8 D ay of Discovery. This is the calendar day an item malfunction was recorded in the aircraft maintenance record or logbook and is excluded from the interval established by the assigned repair category.
1.7.9 D eactivated (or Secured) . When the MEL refers to an item as “deactivated” or “secured,” or both, the specified item must be put into an acceptable condition for safe flight (refer to § 91.7). An acceptable method of deactivating or securing may be recommended by the manufacturer or established by the aircraft operator.
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1.7.10 D eferral. A deferral is t he term used to describe the authorization for an operator to delay repair and continue operating with a required item inoperative, under the authority of its FAA-approved MEL. Authority to defer repair of an inoperative item is subject to specific conditions and limitations, as described in the associated proviso.
1.7.11 Deleted. “D eleted” in the “Remarks or Exceptions” column indicates the item was previously listed, but is no longer addressed by the MMEL.
1.7.12 Dynamic Regulatory System (DRS) . DRS is an FAA website that contains regulatory, policy, and guidance information. DRS can be accessed through the FAA home page or at https://drs.faa.gov.
1.7.13 Excess Items. Excess items are items that have been installed in a quantity greater than that required by 14 CFR.
1.7.14 Extended Operations (ETOPS). ETOPS is an a irplane flight operation, in an airplane with two or more engines that complies with the part 25 ETOPS requirements, during which a portion of the flight is conducted with an extended Maximum Diversion Time, as defined by § 121.7.
Note: To obtain ETOPS approval, the specific airplane/engine combination must be certificated to required ETOPS and transport category standards. Refer to §§ 25.3 and 121.162 and part 135 appendix G.
1.7.15 Flight-Day. A flight-day is a 24-hour period (from midnight to midnight) either in Coordinated Universal Time (UTC) or local time, as established by the aircraft operator, during which at least one flight is initiated for the affected aircraft.
1.7.16 Flight Standards Service (FS). FS is the FAA office that promotes safe air transportation by setting the standards for certification and oversight of airmen, air operators, air agencies, and designees. FS promotes safety of flight of civil aircraft and air commerce by, amongst others:
• Acco mp lishing certification, inspection, surveillance, investigation, and enforcement;
• Setting regulations and standards; and
• Managing the system for registration of civil aircraft and certification of airmen.
1.7.17 F light Operations Evaluation Board (FOEB). An FOEB is a group of technically qualified specialists, engineering representatives, and FAA AED aviation safety inspectors (ASI) responsible for developing MMELs from the one proposed by the aircraft manufacturer. An aircraft MMEL is usually developed during initial aircraft certification. The FOEBs are also responsible for developing MMEL revisions.
1.7.18 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
1-5 provide immediate relief for items required by a new regulatory requirement, policy change, or new technology.
1.7.19 Ite m. An item is an instrument, equipment, system, component, message, or function that is installed on or exhibited by the aircraft.
1.7.20 ATA iSpec 2200. A suite of data specifications and modules for the digital representation and exchange of technical data. The iSpec 2200 system incorporates previous ATA 100 and 2100 specs with improved structure and content of aircraft system and component nomenclature. This minimizes the cost and effort expended by operators and manufacturers in managing inventory.
1.7.21 Joint Aircraft System/Component (JASC) Code. The JASC code is a modified version of the ATA code developed by the FAA to address the need for an international standardization of aircraft system codes. It uses a four-digit format along with an abbreviated code title. For additional information, refer to the FAA Joint Aircraft System/Component Code Table and Definitions at https://avinfo.faa.gov/sdrx/documents/JASC_Code.pdf. (Also refer to i Spec 2200.)
1.7.22 Maintenance (M) Procedure. An (M) abbreviation indicates a requirement for a maintenance procedure that must be accomplished prior to operation with the listed item inoperative. Normally, these procedures are accomplished by 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. Appropriate procedures are required to be produced as a part of the aircraft operator’s manual or MEL. See (M) and (O) procedures in Chapter 3, Minimum Equipment List (MEL)—Content, paragraph 3.9.
1.7.23 Master Minimum Equipment List (MMEL).
1.7.23.1 An MMEL is a type-specific master list of aircraft items that may be inoperative under certain conditions while maintaining the aircraft’s airworthiness and an ALoS. All MMELs are developed and revised by the FOEB, receive concurrence from the FAA Safety Standards divisions (the Air Transportation Division, the Aircraft Maintenance Division, and the General Aviation and Commercial Division) and are approved by the AED manager.
An MMEL is the document on which an operator bases its MEL. All MMELs are located in the FAA DRS website.
1.7.23.2 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 that of the FAA. BASAs are implemented through associated procedures. Refer to country-specific BASAs for MMEL considerations relating to foreign type-certificated aircraft validated under Implementation Procedures for
1-6 Ai rworthiness (IPA). The BASAs and associated IPAs may be found at http s://www.faa.gov/aircraft/air_cert/international/bilateral_agreements/. This information may be helpful for MMEL/MEL development and FAA TC or Supplemental Type Certificate (STC) application packages.
1.7.24 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. PLs are available under the “MELs and AED Guidance Documents” tab on DRS.
1.7.25 Make/Mod el/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.
1.7.26 Managemen t Specification (MSpec). An MSpec is an authorization issued to part 91K operators by the FAA Administrator via a Letter of Authorization (LOA). An MSpec is equivalent to the OpSpec issued to part 121 or 135 operators.
Note: For the purposes of this AC , the term “OpSpec/MSpec” is used. (See “Operations Specification (OpSpec)” below.)
1.7.27 Minimum Equipment List (MEL). An MEL is an operator-speci fic, FAA-approved document that includes a list of items that may be inoperative during a flight. An MEL constitutes an approved change in the aircraft type design.
1.7.28 Moved. “Moved” in the “Remarks or Exceptions” column indicates the item was moved to a different chapter in the MMEL or an FAA-approved document.
1.7.29 Nonessential Equipment and Furnishings (NEF). NE Fs are those items installed on the aircraft as part of the original TC, STC, Engineering Order (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 rules or operational rules. They are those 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 instrument and equipment items already identified in the MEL or CDL of the applicable aircraft. They do not include instrument and equipment items that are functionally required to meet the certification rule or for compliance with any operational rule. See Chapter 10 for additional information on an NEF program.
1.7.30 Note(s). No tes provide additional information for crewmember or maintenance consideration. Notes are used to identify applicable material which is 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 amended, deleted, or added to the MEL by the aircraft operator, as appropriate. Notes are not a part of the provisos.
1.7.31 Number Installed. Th is column indicates the number (quantity) of items normally installed in the aircraft. This number represents the aircraft configuration(s) considered in
1-7 developing an MMEL. If the number is variable or impractical to determine
(e.g., optional equipment, fleet configuration differences, cockpit or cabin lighting items, cargo restraint components, flight data recorder (FDR) parameters), a number is not required and the dash “-” symbol is used instead. A dash or “N/A” (not applicable) may also be used for en route flight advisory service (EFAS) message relief.
1.7.32 Number Required for Dispatch. This column indicates the minimum number (quantity) of items required for operation, providing the conditions specified in the “Remarks or Exceptions” column are met. Where the MMEL shows a variable number “-” required for dispatch, the aircraft operator’s 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 “-” where the number required is based on the conditions of flight, such as adequate cockpit lighting or when operations are conducted under more than one set of operating rules.
1.7.33 O perations (O) Procedure. This symbol indicates a requirement for a specific operations procedure that must be accomplished in planning for or operating 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. The satisfactory accomplishment of all procedures, regardless of who performs them, is the responsibility of the aircraft operator. Appropriate procedures are required to be produced as a part of the aircraft operator’s manual or MEL.
1.7.34 O perator. This AC uses the singular term “operator” for simplicity. Unless otherwise noted, the term “operator” when used in this AC applies to a program manager conducting part 91K operations or a certificate holder conducting operations under part 121, 125, or 135, as applicable.
1.7.35 O perations Specification (OpSpec) . An OpSpec is a document issued under 14 CFR part 119 to parts 121, 125, and 135 operators that contains the authorizations, limitations, and certain procedures under which each kind of operation, if applicable, is to be conducted; and certain other procedures under which each class and size of aircraft is to be operated.
1.7.36 P rincipal 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: Avionics (PAI), Maintenance (PMI), and Operations (POI). PIs have FAA administrative authority to evaluate and approve an operator’s manuals, including the MEL.
1.7.37 P roviso. A proviso is used to stipulate conditions or limitations that must be complied with for operation with the listed item inoperative.
1.7.38 R emarks or Exceptions . The “Remarks or Exceptions” column includes the Maintenance (M) and Operations (O) indicators, a statement either prohibiting or permitting operation with a specific number of items inoperative, provisos, and appropriate notes.
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1.7.39 Responsible Aircraft Certification Service Office. The Aircraft Certification Service office performs aircraft certification duties and administers most type certification and continuous airworthiness program activities.
1.7.40 R esponsible Flight Standards Office. The Flight Standards office with oversight responsibility of an operator’s MEL and MEL management program. The term applies to a Certificate Management Office (CMO), Flight Standards District Office (FSDO), or an International Field Office (IFO).
1.7.41 S afety Assurance. Safety assurance is one of the four components of the Safety Management System (SMS), whereby an operator develops and maintains processes to monitor the safety performance of the organization.
1.7.42 S afety Management System (SMS) . SMS is the formal, top-down, organization-wide approach to managing safety risk and assuring the effectiveness of safety risk controls. It includes systematic procedures, practices, and policies for the management of safety risk.
An SMS program is required for part 121 operators in accordance with 14 CFR part 5.
Other operators may choose to implement SMS voluntarily.
1.7.43 S afety Risk Management (SRM) . SRM is a formal process of controlling safety risk by identifying hazards and analyzing and controlling risk. SRM is one of the four components of SMS, the others being safety policy, safety assurance, and safety promotion. SRM requires an accurate description of the application of the system, or subsystem, risk management principles, and processes.
1.7.44 S upplemental Type Certificate (STC) . An STC is 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.
1.7.45 T akeoff. For the purposes of MEL relief, takeoff is considered to be the point at which the pilot physically begins to apply power to initiate the takeoff from the runway or takeoff surface.
1.7.46 T riple Asterisk (***). The triple asterisk in the “Item” column indicates an item that may have been installed on some but not all aircraft covered by an MMEL. This item may be included in the aircraft operator’s MEL after the approving office has determined the item has been or will be imminently installed on one or more of the aircraft operator’s aircraft. This symbol, however, should not be carried forward into the aircraft operator’s MEL. It should be noted that neither this policy nor the use of this symbol provides authority to install or remove an item from an aircraft.
1.7.47 V ertical Bar (Change Bar) . A vertical bar indicates a change, addition, or deletion of content in the adjacent row(s) of text for the current revision of that page only.
1.8 Regulatory Requirements. Regulatory requirements for parts 91K, 121, 125, and 135 operations, in accordance with §§ 91.1115, 121.628, 125.201, and 135.179, as applicable,