2.5 MMEL Policy

This section gives details of Transport Canada policy governing the development of a MMEL. The policy material provided is applicable to both domestic and foreign manufactured aircraft unless otherwise stated.

2.5.1 Development of a MMEL

Canadian aircraft manufacturers must produce a MMEL if they wish their aircraft to be operated with specified equipment inoperative. Where possible, the approval process for such a MMEL will take place concurrently with the type certification process, but the development of an approved MMEL is not a condition of aircraft type certification.

2.5.2 MMEL Source

  1. Domestic Aircraft

    The development and approval of a MMEL is heavily dependent on the aircraft manufacturer as the primary source of information on any new aircraft and its systems. Transport Canada will not normally undertake either the origination or production of MMELs. The drafting of a MMEL is the manufacturer's responsibility.

  2. Foreign Aircraft

    The usual source will be the MMEL approved by the country of manufacture as modified by a TC Supplement, produced and approved by Transport Canada. Transport Canada may elect to use a FAA or JAA MMEL, even if they are not the country of manufacture, if it is deemed to be more appropriate.

  3. Supplemental Type Certificate (STC)

    MMEL relief for new or modified equipment must be considered during the approval process for the STC. If the developer of an STC for a domestic aircraft seeks MMEL relief for equipment affected by the STC, the developer of the STC is responsible for the drafting of a MMEL justification and the development of procedures for the equipment or systems affected by the STC.

2.5.3 MMEL Justification

The MMEL must be supported by appropriate engineering justification and special procedures where applicable. The engineering justification may include a quantitative and/or qualitative safety analysis, a rationale showing system redundancy, AFM limitations or any other technical justification supporting the prescribed level of safety.

2.5.4 MMEL Review Group

  1. Domestic Aircraft

    The Transport Canada approval process for a specific aircraft type will be coordinated by the MMEL Review Group Chairperson. The constitution of the MMEL Review Group and the functions and duties of the chairperson are described in AppendixC.

  2. Foreign Aircraft

    The MMEL Review Group will also include the specialists involved in the Transport Canada validation/familiarization of the type design.

2.5.5 Participation of Air Operators

  1. Domestically Manufactured Aircraft

    Air operators of an aircraft type are encouraged to participate in the MMEL development and approval process. This will be accomplished through meetings convened by the MMEL Review Group Chairperson. Requests for changes to an existing MMEL will be considered through application to the MMEL Review Group. All requests must be accompanied by adequate technical justification and should include the manufacturer's support and documentation.

  2. Foreign Manufactured Aircraft

    To enable the publication of the TC Supplement within the time constraints imposed by the validation/familiarization process, air operator input will be sought only after initial publication of the TC Supplement.

  3. After initial publication of the TC Supplement, aircraft operator submissions may be made directly to the MMEL Review Group using the procedures noted in paragraph2.6.4.a.

2.5.6 Foreign MMELs

  1. Transport Canada may accept foreign MMELs approved by the regulatory authority of the country of manufacture, as published. Transport Canada will evaluate the foreign MMEL to determine the basis and justification for each MMEL item.

  2. When required, Canadian interpretations, additional airworthiness requirements and operating rules will be addressed by a TC Supplement, which will be developed by the MMEL Review Group and produced by Transport Canada. The TC Supplement will constitute a mandatory change to the foreign MMEL and will be used in conjunction with it. Where the two documents differ, the TC Supplement will supersede the accepted MMEL.

2.5.7 Notification of Approval

All MMELs and TC Supplements approved for Canadian operators are listed on the MMEL web page and in the Status of Current MMEL List. Most are available in electronic format and therefore can be viewed or downloaded from the MMEL web page (See Section3.8.7).

2.5.8 Third Country MMELs

Transport Canada will not normally accept a MMEL produced by a third party (an example would be a U.S. MMEL for a European aircraft). However, exceptions may be made, particularly for older aircraft, if no other source is available or if the use of a third party's MMEL is more appropriate. Such MMELs should be submitted for acceptance and be supported by the aircraft manufacturer with appropriate engineering justification. Only those items which can be adequately substantiated against the levels of safety discussed in the MMEL Philosophy section of this document will be approved for Canadian use. Other items will be deleted using the TC Supplement.

Temporary or Interim MMEL Revisions

Manufacturers may issue temporary or interim revisions to their MMELs which may not be incorporated into the permanent revision for some time. Temporary or interim MMEL revisions may be incorporated into an operator's MEL, upon receipt, provided that they are not less restrictive than any existing MMEL items or TC Supplement.

2.5.9 MMEL Page Format

  1. MMELs for domestic aircraft and TC Supplements for MMELs to foreign aircraft will be published in the "four column format" where columns 1 to 4 will contain respectively the name of the item and category, number installed, number required for dispatch and remarks or exceptions.

  2. A sample page is provided in AppendixE. Other formats may be accepted for foreign MMELs provided they are clear and unambiguous. Each MMEL will be preceded by an acceptable preamble. An example is given in AppendixF.

2.5.10 MMEL Format

  1. Each MMEL should contain a cover/approval page, a Log of Revisions, a Reason for Changes page, a List of Effective Pages, a Table of Contents, an explanation of the symbols used in the MMEL and a definition of any terms having special meaning in the context of the MMEL. Each item of equipment listed in the MMEL shall be described and identified in accordance with the Air Transport Association (ATA) specification 100 code system. (See Appendix T.) The number of each item of equipment installed and the number required to be operative for dispatch shall be stated in the appropriate columns.

  2. Any conditions associated with inoperative equipment, required to maintain a level of safety, shall be included in the "Remarks or Exceptions" column.

  3. When practicable, the switch, lever, gauge or indicator of a particular item of equipment, should be identified. Foreign MMELs may indicate a requirement to placard inoperative equipment by use of an asterisk (*) in column 4 to inform crew members of its condition. For domestic MMELs, a definition has been added which states that each inoperative item must be placarded to inform and remind the crew members and maintenance personnel of the equipment condition.

2.5.11 Operating and Maintenance Procedures

Any inoperative item of equipment in the MMEL which would require an operational or maintenance procedure to ensure the required level of safety, shall be so identified by an appropriate symbol in the "Remarks or Exceptions" column of the MMEL. This will normally be "(O)" for an operational procedure and "(M)" or "(M#)" for a maintenance procedure. (O)(M) or (O)(M#) means both operational and maintenance procedures are required. Details of such procedures must be made available for review during the MMEL approval process as they form part of the justification supporting inclusion of an item in the MMEL. However, the approval of the procedures themselves will not be a part of the MMEL approval process. Where applicable, the limitations, procedures and remarks for individual MMEL items should cover at least day, night, VMC, IMC, ETOPS, icing, rain, and Category II/III.

(M) or (M#) procedures are to be accomplished once prior to the first flight with MMEL relief. If there is a requirement to perform the task on an alternate frequency, this will be clearly stated in the remarks column of the MMEL.

2.5.12 Prohibited Items

  1. The MMEL shall not include any item of equipment which, if inoperative, is likely to significantly affect the take-off, landing or climb performance of the aircraft or associated landing speeds presented in the approved Aircraft Flight Manual (AFM) unless the AFM specifies the effect and the MMEL draws attention to this fact.

  2. No item shall be included in the MMEL which conflicts with the limitations, or invalidates or reduce the ability to perform an emergency procedure in the AFM or in an airworthiness directive unless the AFM or directive provide otherwise.

  3. The MMEL shall not include any part or structural component of the aircraft which is the subject of the Configuration Deviation List (CDL).

2.5.13 Equipment Required by Operating Regulation

When an item of equipment is required to be installed and operative under particular circumstances by the Canadian Aviation Regulations such equipment may be defined in the remarks column of the MMEL by the words "As required by Regulation".

Note: Other MMELs such as those for U.S. manufactured aircraft may contain phrases such as "As required by FARs". Such phrases should be interpreted to mean "As required by Regulation".

2.5.14 Repair Interval Categories

  1. The maximum time an aircraft may be operated between the discovery of an inoperative item and its repair will be specified in the MMEL. Passenger convenience items such as reading lights may have no specified repair interval (no category).

  2. The category of all other inoperative items will be determined according to the time intervals specified below.

Category A

Items in this category shall be repaired within the time interval specified in the "Remarks or Exceptions" column of the air operator's approved MEL. Whenever the proviso in the "Remarks or Exceptions" column of the MMEL states cycles or flight time, the time interval begins with the next flight. Whenever the time interval is listed as flight days, the time interval begins on the flight day following the day of discovery.

Time Limited Dispatch - Some MMEL's for aircraft that are equipped with FADEC engines have relief that is subject to time limited dispatch expressed as a specific number of engine hours, and will start in accordance with the times established by the engine manufacturer or as indicated in the remarks column of the MMEL. Time limited relief cannot be extended.

Category B

Items in this category shall be repaired within 3 consecutive calendar days excluding the day of discovery.

Category C

Items in this category shall be repaired within 10 consecutive calendar days, excluding the day of discovery.

Category D

Items in this category shall be repaired within 120 consecutive calendar days, excluding the day of discovery. To be considered for placement in Category D, the item must be of an optional nature, or excess equipment which an air operator may, at his/her discretion, deactivate, remove from or install on an aircraft.

To be approved for CategoryD, the item must meet the following criteria:

  1. the absence of the item does not adversely affect crew member's workload;
  2. the crew members do not rely on the function of that item on a routine or continuous basis; and,
  3. the crew members' training, subsequent habit patterns and procedures do not rely on the use of that item.

Category D relief will generally not be approved for equipment which is considered to increase the level of safety, even if that equipment is of an optional nature.

Category Format

The category of each item in the MMEL is to be inserted in column 1 adjacent to column 2.

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