Pentagon orders engine vibration fix for entire F-35 fleet worldwide

All F-35 fighter jets should be retrofitted within 90 days with a fix intended to solve a potential engine vibration problem, the F-35 Joint Program Office said on March 2.

The JPO issued an order on March 1 recommending the fleetwide retrofit — globally, not just American aircraft — over the next three months, as well as immediately putting it in place for a “small number” of fighters that have been grounded since December, Defense News reports.

In a statement to reporters on Thursday, the JPO said it is not grounding other F-35s, aside from the newly built fighters believed to be susceptible to the vibration problem in their Pratt & Whitney-made F135 engines and that have been grounded for more than two and a half months.

The office also said it plans to work with the military services flying the F-35 and international partners to ensure they understand the technical order. “The safety of flight crews is the JPO’s primary concern,” the JPO said.

F-35 deliveries were halted in mid-December after a mishap involving a new F-35B in Fort Worth, Texas. That F-35B, which was undergoing a quality check flight, was videotaped bouncing, tipping forward, and spinning around on the ground before its pilot ejected safely.

After that mishap, Lockheed Martin, which makes the aircraft, stopped accepting flights for new F-35s. Those flights must occur before the company delivers the jets to the US government. Those groundings had the effect of halting deliveries.

Lockheed confirmed to Defense News on March 2 that it has not yet resumed flight operations or deliveries of new F-35s, most of which are constructed at its Fort Worth, Texas, facility. Lockheed Martin has delivered more than 890 F-35s around the world.

The Pentagon and Pratt & Whitney halted engine deliveries later in December. An investigation found a vibration issue in the engine led to the mishap. The JPO said that the vibration issue was a “rare occurrence” and announced in February that Pratt & Whitney, owned by Raytheon Technologies, and other engineers had developed a fix for it.

The JPO on March 2 said the vast majority of F-35s are not experiencing this engine vibration problem. But it is retrofitting the entire fleet because the fix is “inexpensive [and] non-intrusive,” and will mean all F-35 engines have the same configuration.