Gotta have it?

It’s understandable that a new private pilot might be a little hazy on the details of MELs, as they’re not likely to be encountered in smaller training aircraft. A pass through FAR Part 91 explains why—as well as why MELs are relevant and important to understand for pilots of turbine-powered airplanes.

FAR 91.213 (inoperative instruments and equipment) says that with a few key exceptions “no person may take off in an aircraft with inoperative instruments or equipment installed.” The exception with which most private pilots are used to dealing applies only to small (under 12,500 pounds maximum takeoff weight) and nonturbine-powered airplanes. It stipulates equipment may be inoperative provided it is not required: by the FARs (e.g., an altimeter is necessary for all operations); by the original equipment manufacturer (OEM) through an aircraft equipment list, or kinds of operation equipment list (KOEL) (e.g., Cirrus with two alternators must have alternator 1 operative); or by an airworthiness directive.

Pilots of turbine aircraft, however, may not use this process to determine if a flight can be conducted with inoperative equipment. They may not fly with any equipment in the airplane not working, unless “an approved minimum equipment list exists for that aircraft, [and] the aircraft has within it a letter of authorization (LOA) issued by the FAA…authorizing operation of the aircraft under the minimum equipment list.” This LOA is issued to a specific combination of operator and N number aircraft. If my hangar neighbor has an LOA and approved MEL for his Piper Meridian or Embraer Phenom, it doesn’t mean I can make a copy and use it for mine, even if our airplanes are identical.

If my hangar neighbor has a letter of authorization and approved MEL for his Piper Meridian, it doesn’t mean I can make a copy and use it for mine, even if our airplanes are identical.The process of creating and receiving approval for an MEL is time consuming, but fortunately for Part 91 operators a more expedient option exists. Manufacturers of turbine aircraft create and periodically update a master minimum equipment list (MMEL) for their aircraft, which receives approval directly from the FAA. Operators may submit to the FAA a package consisting of the MMEL and a separate document detailing how they will adapt some of the generic language in the MMEL to their operation. Together with an LOA authorizing use of the MMEL as an MEL, this package is considered to be the FAA-approved MEL.

Once approved to do so, a pilot can now consult his MEL to determine if a flight can be made with given equipment inoperative. For some cases the process is simple—a Phenom 100 pilot with an inoperative cockpit voice recorder (CVR), would consult the MEL (see chart, page T-18) and see the flight may be operated with no CVR. In most cases, however, some restriction on operation or maintenance steps that must be taken prior to flight are specified.

These operational and maintenance procedures are indicated by the presence of an “O” or “M” in the remarks and exceptions column of the MEL. If the Phenom pilot had an inoperative outflow valve (a key part of the pressurization system), flight would only be legal after a mechanic had physically removed another safety valve, and the pilot would be limited to making unpressurized flights at or below 10,000 feet msl (see chart, page T-18).

Operating with an MEL isn’t permission to fly an aircraft forever with broken parts. For-hire operators must abide by repair categories specified in the MEL, varying from as little as a single flight to as much as four months. Part 91 operators are given more latitude from the FAA; they need not comply with the “A, B, C, or D” calendar-based repair categories, but only with any limits specified in the remarks and exceptions. Again, even this more lenient procedure isn’t intended to be permission for continuous deferral of maintenance; at the next required aircraft inspection all inoperative equipment must be repaired or removed.

One note of interest as this issue goes to press: In the past few months a controversy has arisen regarding use of an MMEL as an MEL for operators who travel to Europe. The French Safety Oversight Authority conducts the dreaded “safety assessment of foreign aircraft (SAFA)” inspections of aircraft visiting France—think ramp check on steroids, taking up to two hours. France has stated it will no longer accept the use of an MMEL as an MEL, as this process allegedly doesn’t comply with ICAO guidelines.

As a result, some operators are proactively beginning the process of creating their own MELs, while others are anticipating push-back from the FAA, which would be faced with thousands of man-hours of new work should every operator in the U.S. need to have a custom MEL approved. As the process to create and have approved a custom MEL can be very lengthy, international operators would do well to watch this issue closely.AOPA

Neil Singer is a master CFI with more than 8,500 hours.