An F-35A flies a flight test at sunset at Edwards Air Force Base, California. (Lockheed Martin)
LONDON — Inspectors now believe they know the cause of the fire that damaged an F-35A the morning of June 23, but remain unclear on why the incident occurred.
The fire was caused by “excessive” rubbing of fan blades inside the F135 engine that powers the plane, Frank Kendall, the Pentagon’s head of acquisitions, told reporters today in London. The news was reported by multiple outlets, including Reuters.
However, the bigger question remains about whether the incident was a one-off situation or whether it is the result of a previously unknown fleet-wide defect. Sources indicated to Defense News it is likely not a major flaw across all the planes, but investigators continue to work the issue.
Kendall is expected to give more details Monday during a public event at the Farnborough International Airshow.
The fire, which heavily damaged the F-35A model known as AF-27, eventually led to the grounding of the entire F-35 fleet on July 3. That in turn caused the jet to miss its much-ballyhooed international debut at the Royal International Air Tattoo last week.
As the planes remain grounded, a follow-up appearance at the Farnborough International Airshow is also now in doubt, with organizers already ruling it out for Monday.
This is the second recent fan-related incident for F135 engine, designed by Pratt & Whitney. However, the last incident occurred in a different part of the engine, making it unlikely the two are related.
Bennett Crosswell, the head of Pratt’s military engine group, defended his company’s work on the platform Sunday.
“This is a challenging time for us as we go through this investigation, but overall when you look at the engine and how it’s done, mission readiness is over 98 percent in flight test, and high-nineties for operational use,” Crosswell said. “The engine is delivering, and we have to continue to do that going forward.”
“We’re focused on all our programs, but certainly the f-35 program is the largest program going forward. It’s still in development, in production and in sustainment. Being focused on all three phases and continuing to deliver for our customer, that’s really an important focus for us.”