MMEL Policy Letter (PL) 25 - Revision 21 - MMEL and MEL Definitions

Sep 16, 2026

MMEL Policy Letter (PL) 25, Revision 21, dated May 11, 2015, provides an approved addendum with a consolidated list of definitions for use in MMEL and MEL documents. Operators may revise their MEL to copy the applicable definitions, while maintaining the same intent and not making requirements less restrictive. The letter includes guidance on CFR references, administrative control items, and MEL definition requirements, and documents changes made across prior revisions.

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MMEL Policy Letter (PL) 25 - Revision 21

Document control information

Subject: MMEL and MEL Definitions

Purpose

Discussion (revision history)

Policy and notes

Administrative Control Item (ACI)

Federal Aviation Administration | MMEL Policy Letter (PL) 25 , Revision 21 GC | | | --- | --- | | Date: | May 11, 2015 | | To: | All Aircraft Evaluation Group Managers | | From: | Manager, Air Transportation Division, AFS-200 | | Reply To Attn Of: | Manager, New Program Implementation and International Support Branch, AFS-240 | | MMEL GLOBAL CHANGE (GC)
This GC is an approved addendum to all existing MMEL documents. Operators may seek use of the definitions contained in this policy letter by revising their Minimum Equipment List (MEL) . In doing so, each definition must be copied as appropriate in the Operator’s MEL. Approval of a revised MEL is gained utilizing established procedures, through the Operator’s assigned Principal Operations Inspector (POI) .
GC expiration date 12/17/2016 . | | Subject: MMEL and MEL Definitions MMEL CODE: 00 (GENERAL) REFERENCE: Policy Letter 25, Revision 20, dated December 17, 2012 Policy Letter 25, Revision 19, dated October 9, 2012 Policy Letter 25, Revision 18, dated July 27, 2012 Policy Letter 25, Revision 17, dated January 20 , 2011 Policy Letter 25, Revision 16, dated April 2, 2010 Policy Letter 25, Revision 15, dated November 2, 2009 Policy Letter 25, Revision 14, dated August 26, 2008 Policy Letter 25, Revision 13, dated September 11, 2006 Policy Letter 25, Revision 12, dated June 5, 2006 Policy Letter 25, Revision 11, dated July 5, 2005 Policy Letter 25, Revision 9, dated August 15,1997 Policy Letter 25, Revision 8, dated January 31, 1995 PURPOSE: To provide a list of definitions for use in MMELs and MELs. DISCUSSION: Revision 21: Removed all reference to part 382 accessible lavatory. Definition numbers were not changed. Revision 20: Adds a third note to the “Policy” paragraph, page 2 ; corrects discrepancies found in definition 32. H. Revision 19: Updates definition of “Take-0ff”. Adds the phrase, “See PL-25 Policy Statement (page 2)” to the “Notes” of several definitions found in Appendix B of this PL. Revision 18 : Removes 14 CFR Part 382 items from NEF definition \#21 and adds accessible lavatory items, definition \#1, listing 14 CFR Part 382 general items, and specific 382.63 and 382.71 items. Places definitions in alphabetical order. Consolidates PL-70 into Appendix B of this PL. Also adds the following definitions: Air Transport Association (ATA) System Page (\#3) , operative (\#22) , and takeoff (\#25) . Adds Appendix B, MEL Definition Requirements. Aligns the definitions of this PL with the definitions found in FAA Order 8900 . 1, Volume 4 , Chapter 4, Section 1. DISCUSSION (continued): Note: ATA changed its name in 2011 to Airlines for America (A4A) . ATA and A4A are interchangeable. Revision 17: Adds a Note to definition 3, adds the Boeing model 747-8 to definition 23a and adds Appendix A. Definitions 22 and 24 are also modified for clarity. Revision 16: Corrected revision bar requirement in definition \#1e; deletes the Passenger Convenience definition \#21; revises the Electronic Fault Alerting System for Airbus aircraft (definition \#23c. ); adds new MMEL definition \#31 for HMV. Revision 15: Revised definition 22.A. “Category A Repair Interval” by including a reference to “calendar days”, aligning the criteria for Day of Discovery with definition 27 “Day of Discovery”. A-380 aircraft added to definitions, 23c. Revision 14: Revised definition \#1a to include the listing of the repair interval categories (A, B, C and D) in column 1, revises definition \#7 to align with recent ETOPS rulemaking, adds day of discovery to definition \#22 Category A, adds MEL repair interval extensions information to definition \#22, adds "787" to definition \#23a, adds G-150 and G-200 to definition \#23g, corrects NEF Definition \#30 to align with FSIMS 8900.1. Volume 4 (Aircraft Equipment and Operational Authorizations) Chapter 4 (MEL and CDL) Section 11 (NEF) paragraph 4-898. Revision 13: Added clarification to definition 10.

FAQs

What is the purpose of MMEL Policy Letter (PL) 25, Revision 21?

It provides a list of definitions for use in MMELs and MELs.

Can operators copy the MMEL definitions into their MEL, and how should they handle approvals?

Operators may revise their MEL by copying the definitions as appropriate, and approval of the revised MEL is obtained using established procedures through the operator’s assigned POI.

What key change does Revision 21 describe?

It removed references to part 382 accessible lavatory; definition numbers were not changed.

Sep 16, 2026

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