NBAA News Hour Explores Common ‘Gotchas’ with MELs and Deferred Maintenance

Oct. 16, 2020

NBAA News Hour on Oct. 16 examined the nuances of minimum equipment lists (MELs) and deferred maintenance items allowable under the Federal Aviation Regulations (FARs).

Panel moderator Greg Hamelink, chair of the NBAA Maintenance Committee, began the conversation with the example of inoperative ADS-B equipment required to operate in most U.S. airspace.

While many such equipment failures could ground the aircraft pending repair, “there’s a caveat here,” Hamelink noted. “FAR 91.225 allows you to operate with ADS-B inoperative, and the FAA created a [website to] get an authorization for a deviation to operate without ADS-B. A pilot or flight crew member could do this deferral for maintenance.”

Tom Atzert, president of Leading Edge Aviation Technical Services, shared his insights on use of non-essential furnishing (NEF) lists of items that have no effect on the safe operation of the aircraft. Such lists may not encompass all that might break during normal operation, but there is a way to handle the unexpected.

“The FAA guidance material for NEF provides for a process to defer items that are not on the list … [and] come to the conclusion that the item is, in fact, a non-essential item, and thus a candidate for deferral under the NEF program,” Atzert explained, while also jokingly adding, “Contrary to popular belief, NEF does not mean ‘never, ever fix.'”

Similarly, an aircraft’s configuration deviation list (CDL) enumerates regulator-approved non-structural external parts that may be missing, yet the aircraft may still be airworthy. Hamelink pointed to the Gulfstream G500, which is equipped with 14 static discharge wicks, yet none are required to be present unless the flight crew uses the automatic direction finder (ADF) or utilizes high-frequency (HF) communications.

“This was a ‘gotcha’ early in my career starting out as an avionics technician,” added Stewart D’Leon, NBAA director for technical operations. “With no static wicks in stock, [people] were saying, ‘Well, we can’t fly!’ Luckily, we had some great leadership that said, ‘go look at the flight manual.'”

The Oct. 16 webinar is part of an ongoing NBAA series of presentations, articles and podcasts exploring proper understanding and use of MELs within business aviation. Mike Wuebbling, senior maintenance manager for Boeing’s Executive Flight Operations, noted the master minimum equipment list (MMEL) issued by the OEM often must be tailored to meet the needs of a specific flight operation or aircraft.

“If something doesn’t make sense, do not be afraid to pick up the phone and call the center that’s responsible for your aircraft,” he suggested. “Many times we’ve run into an interpretation that was in error. Once you identify that, you can send a letter to the FAA and request that clarification to change that MEL.”