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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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5-1 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 accessible to the PIC. The MEL may be available in hardcopy (printed) or digital format. 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 newly identified inoperative items 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 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)/Pilot’s Operating Handbook (POH)-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 f ailure 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;
• En route environment;
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• Diversion and alternate airport options;
• Additional crew workload caused by inoperative items;
• Crew fatigue; and
• Other human factor considerations.
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 available to the pilot 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 accessible 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. T he (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. Th e (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,
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.
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.
Instrument or equipment item is discovered to be inoperative before takeoff.
Make entry in the aircraft maintenance records.
Does the MEL allow the item to be deferred? If NO, repair item before takeoff.
If YES, review all applicable MEL procedures, conditions, or limitations for that item.
Is the operator able to comply with and perform all applicable MEL procedures, If NO, repair item before takeoff.
conditions, or limitations?
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, perform applicable MEL procedures, placard item appropriately, and return aircraft to service.
• 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.
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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 R equest 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. E xplain 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.