NCO.GEN.155 Minimum equipment list

CONTENT AND APPROVAL OF THE MEL

(a)When an MEL is established, the operator should amend the MEL after any applicable change to the MMEL within the acceptable timescales. The following are applicable changes to the MMEL that require amendment of the MEL:

(1)a reduction of the rectification interval;

(2)change of an item, only when the change is applicable to the aircraft or type of operations and is more restrictive;

(3)reduced timescales for the implementation of safety-related amendments may be required by the Agency and/or the competent authority.

(b)An acceptable timescale for notifying the amended MEL to the competent authority is 90 days from the effective date specified in the approved change to the MMEL.

(c)In addition to the list of items and related dispatch conditions, the MEL should contain:

(1)a preamble, including guidance and definitions for flight crew members and maintenance personnel using the MEL. The MEL preamble should:

(i)reflect the content of the MMEL preamble as applicable to the MEL scope and extent;

(ii)contain terms and definitions used in the MEL;

(iii)contain any other relevant specific information for the MEL scope and use that is not originally provided in the MMEL;

(iv)provide guidance on how to identify the origin of a failure or malfunction to the extent necessary for appropriate application of the MEL;

(v)provide guidance on the management of multiple unserviceabilities, based on the guidance given in the MMEL; and

(vi)provide guidance on placarding of inoperative items to inform crew members of equipment condition as appropriate. In particular, when such items are accessible to the crew during flight, the control(s) and indicator(s) related to inoperative unit(s) should be clearly placarded.

(2)the revision status of the MMEL upon which the MEL is based and the revision status of the MEL;

(3)the scope, extent and purpose of the MEL;

(4)operational and maintenance procedures as part of the MEL or by means of reference to another appropriate document, based on the operational and maintenance procedures referenced in the MMEL; and

(5)the dispatch conditions associated with flights conducted in accordance with special approvals held by the operator in accordance with Part-SPA.

(d)The operator should:

(1)establish rectification intervals for each inoperative instrument, item of equipment or function listed in the MEL. The rectification interval in the MEL should not be less restrictive than the corresponding rectification interval in the MMEL. The definitions and categories of rectification intervals are provided in CS-MMEL as well as in CS-GEN-MMEL; and

(2)establish an effective rectification programme.

(e)The operator should establish the operational and maintenance procedures referenced in the MEL, taking into account the operational and maintenance procedures referenced in the MMEL. These procedures should be part of the operator’s manuals or the MEL.

(f)The operator should amend the operational and maintenance procedures referenced in the MEL after any applicable change to the operational and maintenance procedures referenced in the MMEL.

(g)Unless otherwise specified in the MEL, the operator should complete:

(1)the operational procedures referenced in the MEL when planning for and/or operating with the listed item inoperative; and

(2)the maintenance procedures referenced in the MEL prior to operating with the listed item inoperative.

FORMAT OF THE MEL The MEL format, the presentation of MEL items and dispatch conditions should:

(a)reflect those of the MMEL;

(b)follow the ATA 100/2200 Specification numbering system for MEL items; and

(c)when different from (a) and (b), be clear and unambiguous.

EXTENT OF THE MEL The operator should include guidance in the MEL on how to deal with any failures that occur between the commencement of the flight and the start of the take-off. If a failure occurs between the commencement of the flight and the start of the take-off, any decision to continue the flight should be subject to pilot judgement and good airmanship. The pilot-in-command may refer to the MEL before any decision to continue the flight is taken.

OPERATIONAL AND MAINTENANCE PROCEDURES

(a)The operational and maintenance procedures referenced in the MEL should be based on the operational and maintenance procedures referenced in the MMEL. Modified procedures may, however, be developed by the operator when they provide the same level of safety as required by the MMEL. Modified maintenance procedures should be developed in accordance with the applicable airworthiness requirements.

(b)Providing appropriate operational and maintenance procedures referenced in the MEL, regardless of who developed them, is the responsibility of the operator.

(c)Any item in the MEL requiring an operational or maintenance procedure to ensure an acceptable level of safety should be so identified in the ‘remarks’ or ‘exceptions’ column/part/section of the MEL. This will normally be ‘(O)’ for an operational procedure, or ‘(M)’ for a maintenance procedure. ‘(O)(M)’ means both operational and maintenance procedures are required.

(d)The satisfactory accomplishment of all procedures, regardless of who performs them, is the responsibility of the operator.

OPERATIONAL AND MAINTENANCE PROCEDURES — APPLICABLE CHANGES

(a)Changes to the operational and maintenance procedures referenced in the MMEL are considered applicable and require the amendment of the maintenance and operating procedures referenced in the MEL when:

(1)the modified procedure is applicable to the operator’s MEL; and

(2)the purpose of this change is to improve compliance with the intent of the associated MMEL dispatch condition.

(b)An acceptable timescale for the amendments of maintenance and operating procedures, as defined in (a), should be 90 days from the date when the amended procedures referenced in the MMEL are made available. Reduced timescales for the implementation of safety-related amendments may be required if the competent authority consider it necessary.

GENERAL

(a)The Minimum Equipment List (MEL) is a document that lists the equipment that may be temporarily inoperative, subject to certain conditions, at the commencement of flight. This document is prepared by the operator for their own particular aircraft, taking account of their aircraft configuration and all those individual variables that cannot be addressed at MMEL level, such as operating environment, route structure, geographic location, aerodromes where spare parts and maintenance capabilities are available, etc.

(b)The MMEL, as defined in the mandatory part of the operational suitability data established in accordance with Regulation (EU) No 748/2012, is developed in compliance with CS-MMEL or CS-GEN-MMEL. These Certification Specifications contain, among other, guidance intended to standardise the level of relief granted in MMELs, in particular for items that are subject to operational requirements. If an MMEL established as part of the operational suitability data is not available and items subject to operational requirements are listed in the available MMEL without specific relief or dispatch conditions but only with a reference to the operational requirements, the operator may refer to CS-MMEL or CS-GEN-MMEL guidance material, as applicable, to develop the relevant MEL content for such items.

SCOPE OF THE MEL

(a)Examples of special approvals in accordance with Part-SPA may be:

(1)RVSM

(2)LVO

(b)When an aircraft has installed equipment which is not required for the operations conducted, the operator may wish to delay rectification of such items for an indefinite period. Such cases are considered to be out of the scope of the MEL, therefore modification of the aircraft is appropriate and deactivation, inhibition or removal of the item should be accomplished by an appropriate approved modification procedure.

PURPOSE OF THE MEL The MEL is an alleviating document having the purpose to identify the minimum equipment and conditions to operate safely an aircraft having inoperative equipment. Its purpose is not, however, to encourage the operation of aircraft with inoperative equipment. It is undesirable for aircraft to be dispatched with inoperative equipment and such operations are permitted only as a result of careful analysis of each item to ensure that the acceptable level of safety, as intended in the applicable airworthiness and operational requirements, is maintained. The continued operation of an aircraft in this condition should be minimised.

OPERATIONAL AND MAINTENANCE PROCEDURES

(a)Operational and maintenance procedures are an integral part of the compensating conditions needed to maintain an acceptable level of safety, enabling the competent authority to approve the MEL.

(b)Normally, operational procedures are accomplished by the flight crew; however, other personnel may be qualified and authorised to perform certain functions.

(c)Normally, maintenance procedures are accomplished by the maintenance personnel; however, other personnel may be qualified and authorised to perform certain functions in accordance with the applicable airworthiness requirements.

(d)Operational and maintenance procedures, regardless of the document where they are contained, should be readily available for use when needed for the application of the MEL.

(e)Unless specifically permitted by a maintenance procedure, an inoperative item may not be removed from the aircraft.