Maintenance: Diligence Required When Returning Aircraft to Service

The COVID-19 pandemic led many operators to temporarily idle their aircraft, requiring maintenance technicians to dust off mothballing procedures not utilized since the Great Recession. Now that some operators are resuming flight operations, it’s equally important that maintenance technicians methodically follow the necessary steps in order to return aircraft to service.

While most business aircraft have sat idle for a shorter period than a decade ago, parking an aircraft for even a few months can be a strenuous process.

“Several steps are required to properly park an aircraft for any length of time,” said Stewart D’Leon, NBAA’s director of technical operations. “Get into both the engine and airframe manuals to find out what timeframes you’re dealing with.”

Maintenance requirements for stored aircraft may be found in Chapter 5 of the respective manufacturer’s airframe and engine maintenance manuals. An operator’s level of compliance with those procedures often influences how easily the aircraft can be returned to service.

“There are very specific paths to maintaining aircraft in different stages of airworthiness,” said Chris Poliak, senior vice president of aircraft maintenance for Executive Jet Management. “But that determination may be more complicated than it might seem. Was the aircraft kept flight-ready or storage-ready? OEMs sometimes define those terms differently.”

Procedures for parking and then returning idled aircraft to service are covered in Chapter 10 of airframe and engine maintenance manuals, and both D’Leon and Poliak recommend going above and beyond those requirements.
“Flight crews should conduct a thorough preflight inspection, particularly looking for damage or evidence that critters have snuck into tight spaces,” D’Leon said. “Operators should also cycle the pressurization system to clear out any dust or smells that may have accumulated.

“I also recommend ground-running the engines in compliance with the aircraft maintenance manual before thinking of taking flight,” he continued. “You don’t want to be on climbout when you discover the engines aren’t producing full power.”

Additional return-to-service steps may include swinging the landing gear to ensure seals are lubricated and free of leaks and running the aircraft’s avionics and cabin connectivity systems before carrying passengers.

“Aircraft electronics don’t like temperature extremes or sitting idle,” D’Leon said. “You should also verify the satcom subscription is paid, as that could present an unpleasant surprise once your principal is onboard.”

Poliak also recommended a thorough shakedown flight prior to the aircraft’s return to service. “This is a good practice, not only to ensure the aircraft’s performance and remedy any gremlins that may pop up; it’s also a valuable opportunity for the crew to reorient themselves and return to the flight deck.”

An operator’s diligence in properly parking an aircraft may also affect the bottom line when the time comes to return it to service.

“This pause has been industrywide, and MROs will certainly examine records closely to ensure operators complied with the required steps,” Poliak said. “If they haven’t, the price for a dedicated engineering report and return to service plan from the manufacturer will far outstrip the cost of keeping up on maintenance.”

For more information, watch the NBAA News Hour webinar Fleet Readiness: Maintenance Considerations Amidst COVID-19.