One of the $14-million engines on a US Air Force F-35A fighter jet was destroyed last year after an engineer left a metal flashlight inside the machine, a military investigation by the Air Force Aircraft Accident Investigation Board published on Thursday reveals.
The pricey plane, part of the Air Force’s 56th Fighter Wing, was undergoing required maintenance at Luke Air Force Base in Glendale, Arizona, when the “accident” occurred on March 15.
Maintenance workers on the military’s F-35 fleet had been ordered to install a metering plug into each engine’s fuel line in December 2022 after a “mishap with the fuel system” that month. The doomed engine at Luke was attached to “one of the last aircraft that needed to be completed,” the investigation stated.
A three-person engineering team from the 62nd Aircraft Maintenance Unit, part of the 56th Aircraft Maintenance Squadron, performed the installation, removing a single panel to insert the plug, and turned on the engines to test the installation for fuel leaks. No alarms or alerts were observed during the 13 minutes they allowed the jet to run, according to the report.
Only when they turned it off did they realize something was amiss, hearing a “clanging sound” and discovering “significant damage.”
One of the engineers subsequently “identified damage to the blades of the engine,” the investigation noted. “He reported the engine damage to the maintenance expeditor and stated, 'I believe I just ingested a flashlight.’”
No humans were injured by the engineers’ mistake, though the cost of the “foreign object damage” was estimated at nearly $4 million. The Air Force reportedly opted to scrap the entire $14-million engine due to the extent of the wreckage.
The investigators concluded the blame lay with the engineers’ failure to follow protocol, which requires a “tool check” prior to testing an engine. They also neglected to attach all needed items to themselves as procedure dictated. The workers tested negative for drugs and alcohol and the report denied “lifestyle factors were a factor in the mishap,” placing some of the blame on official procedures that allowed two members of the maintenance crew to each believe the other had accounted for the errant flashlight before testing the engine.
Officials declined to reveal if anyone had been disciplined over the costly error when asked by military blog Task & Purpose on Friday.
The F-35 is the most expensive weapons system ever built, costing about $1.6 trillion over its development lifetime. The Air Force acknowledged in 2021 – nearly 20 years after the troubled plane was conceived – that it had failed at affordability, costing nearly $36,000 per hour to fly compared to $22,000 per hour for the F-16 it was meant to replace.