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Minimum Equipment List

Introduction:

  • Minimum Equipment Lists (MELs) contain provisions for flight with inoperative equipment based on the conditions of that particular flight
  • Additionally, it provides for equipment repairs to be deferred until a later point in time
  • Determining if an aircraft is airworthy is dependent on the MEL, or FAR 91.213
  • Whether or not your airplane has an MEL, FAR 91.213 still applies to all inoperative equipment and it is your responsibility to find out if your airplane has an MEL
Minimum Equipment List
Figure 1: Minimum Equipment List

Minimum Equipment List:

  • There are two categories of procedures: maintenance procedures (M) and operations procedures (O)
    • An authorized mechanic must complete "M" procedures, but the pilot or flight crew can do "O" procedures
    • Once the owner/operator has created the procedures document, it is presented to the FAA for approval. If granted, the FAA inspector will issue a letter of authorization (LOA). When this letter is received the MEL is complete and the aircraft may be operated within the guidelines of the MEL rather than the procedures outlined in the regulations. This formula will help you remember: MMEL + Procedures Document + LOA = MEL
  • When a part of the aircraft is found to be inoperative the pilot will refer to the MEL
    • If the item is not in the procedures document, the aircraft is grounded
    • If the item is found, the pilot will take the appropriate actions required by the procedures document before flight
    • An MEL is equivalent to a supplemental type certificate and is required to be on board the aircraft during flight
    • The MEL is only valid for a specific aircraft and cannot be transferred to another
  • Column one shows each piece of equipment, listed by system [Figure 1]
  • Column two shows how many of that item are installed on the aircraft [Figure 1]
  • Column three shows the number of items installed that have to be operational for the aircraft to be airworthy [Figure 1]
  • Column four shows remarks or exceptions [Figure 1]

Letter of Authorization (LOA):


Supplemental Type Certificate (STC):

  • Together, the MEL and LOA constitute the STC allowing its use

The Process:

  • Manufacturer submits a list of inoperative equipment to the FAA called a Proposed Master Minimum Equipment List (PMMEL)
  • The FAA approves the PMMEL, creating a Master Minimum Equipment List (MMEL) which is a general MEL for any aircraft of that category, class and type
  • The aircraft owner or operator receives this MMEL, and together with an aircraft mechanic creates an MEL which is specific to that aircraft tail and serial number

References: