Figure 2-1. Example MMEL ATA/JASC Coded System Section Page
TABLE KEY ATA/JASC AIRCRAFT: 1. REPAIR CATEGORY System Code (insert aircraft make and 2. NO. INSTALLED Number model) 3. NO. REQUIRED FOR DISPATCH
4. REMARKS OR EXCEPTIONS
31. INDICATING/RECORDING SYSTEMS Individual Sequence No. Item 1 2 3 4 Item Sequence -30-01 Flight Data Recorder Number (Cont a) Change Bars -03 Flight Data Recorder Up to three recording parameters may Triple Asterisk (FDR) Parameters required by 14 CFR be inoperative provided: a) Cockpit Voice Recorder (CVR) operating rule operates normally, and
b) Repair are made within 20 calendar days. Provisos -04 Flight Data Recorder A May be inoperative provided repairs are (FDR) Parameters not made prior to completion of next required by 14 CFR scheduled inspection of FDR *As Required operating rule by 14 CFR' -05 Underwater Locator May be inoperative or missing provided Statement Device (ULD) device is not required by 14 CFR operating rule.
(O) Symbol -40-01 Amber CHECK C (O) Way be inoperative provided MAINTENANCE CAS CHECK MAINTENANCE procedure in (O) Proviso Message Displayed the AFM is followed to determine APM Item • (Collins Pro Line Fusion Fail message is displayed.
Configuration Equipped Airplanes) Information NOTE: Check Maintenance amber Note caution CAS message may be displayed.
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 2-2
2-3 equipment, or engine instrumentation) installed on different models or series of the aircraft covered by the MMEL.
2.2.4 Repair Categories. T he 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 da sh (-) 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. O perators 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 Single-Engine Airplanes MMEL (generic).
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.
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2.5.1 M andatory 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 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 “MME Ls and AED Guidance Documents” section in DRS at https://drs.faa.gov.
2.6 MMEL PL Global Change (GC) Designation. A GC is newly developed or changed MMEL relief for an item which may or may not be time sensitive. 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 STC Relief Approval Letter (e.g., Design Change Approval Letter). GCs are applicable to many MMELs and will specify applicability (inclusion or exclusion) when not applicable to all aircraft types. GCs may be used to provide immediate relief for items required by a new regulatory requirement, policy change, or new technology. GCs will not typically occur in great number or regularity, and their application and use will typically be limited. An operator is not required to include GC designation relief in their MEL.
2.6.1 G C 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.
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2.6.3 G C Designation Expiration. The GC designation typically has an expiration date. In that case, after the expiration date, GC relief is no longer available for an operator to add to their MEL. An exception exists if the FOEB Chair agrees to extend the GC expiration date. An operator that would like to add GC relief after the expiration date of a GC can submit a request for an expiration date extension to the FOEB Chair. Certain GC policy letters may be published without an expiration date. In those cases, the GC relief remains available to operators for use in their MELs until the policy letter is revised or canceled.
2.6.4 GC Designation Va lidity. The MEL relief available in an MMEL PL with a GC designation is valid until any of the following occur:
• T he aircraft’s MMEL is revised to include information in the applicable MMEL PL;
• An applicable STC Relief Approval Letter is issued; or
• The MMEL PL GC designation is revised, canceled, or expired.
3-1 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. E xcept 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. For information about operating in accordance with § 91.213(d), see Chapter 4.
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 Single-Engine Airplanes MMEL (generic), 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 STC Relief Approval Letter (e.g., Design Change 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 ope rator’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;
Note: Use of MMEL PL with a GC designation is not mandatory; however, if used, the MEL relief may not be less restrictive than the MMEL PL relief.
• 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.
S ection 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
3-3 two types of approvals for MELs under the provisions of § 91.213(a): LOA D095 and D195.
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 M EL 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 Contro l. 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 A ircraft 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 and LOA since they cannot operate under the lessor’s MEL. MEL authorizations are issued to the person exercising operational control.
3.5 F leet 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
3-4 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.
3.5.1 I dentify 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, STC Relief Approval Letter, or any design change approval described in Chapter 10, and the fleet MEL is revised to include the additional items.
4-1 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 R emoval . 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
• A pprove the aircraft for return to service, as appropriate.
4.2.2 D eactivation . 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.
• O nly 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 P lacarding . 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 C ontinued 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, 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;
• En route environment;
• Diversion and alternate airport options;
• Additional crew workload caused by inoperative items;
• Crew fatigue; and
• Other human factor considerations.
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.
Instrument or equipment item is discovered to be inoperative before takeoff.
Make entry in the aircraft maintenance records.
Is the inoperative item required under § 91.213(d)(2)?
Has the maintenance action required by § 91.213(d)(3) occurred?
If YES, repair item before takeoff.
If NO, perform appropriate maintenance action, then conduct safety risk analysis.
If YES, conduct safety risk analysis.
Are the aircraft and crew capable of safely conducting the proposed operation under anticipated flight If NO, repair item before takeoff.
conditions with inoperative items?
If YES, remove or deactivate inoperative item and placard, per § 91.213(d)(3), and retum aircraft to service.
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