Former crash investigators ask questions about 777 engine explosion

Former US NTSB crash investigators Greg Feith and John Goglia are asking the tough questions about the United Airlines 777 Pratt and Whitney engine explosion on Saturday.

Flight UA328 had just taken off from Denver for Honolulu when the right-hand P&W suffered an uncontained failure ripping away the cowling and causing a fire.

Mr. Feith, a former leading crash investigator said: "Following up on the catastrophic engine failure on a United Airlines B777, it is apparent from the Flight Safety Detectives’ examination of passenger pictures show two fan blades failed causing a severe fan disk imbalance."

"It is probable that the failed blades moved forward after separating and exited the engine ahead of the “containment” ring, thus compromising the engine cowling. Once the cowling was structurally deformed, vibration and aerodynamic loads ripped the cowling off the engine."

"Similar engine failure events occurred on a United B777 in 2018 and a JAL 777 in 2020."

He adds that "several issues (among others) that are concerning to me and my Flight Safety Detectives podcast co-host John Goglia are:

The fan blade failure is not a new issue - the key will be to determine the reason(s) for the recurring failure
Is this an aging blade issue
Is there an effective inspection process, especially if the failure is due to internal cracking
Why did the fire in the rear section of the engine continue to burn even after the likely discharge of the suppression system by the crew.
It appears the fire suppression system requirements need to be examined.

Mr. Feith and Mr. Goglia, world-renowned crash investigators host a weekly podcast on a wide range of airline safety issues. The US regulator, the FAA, has issued an emergency airworthiness directive (AD) requiring immediate or stepped-up inspections for P&W-powered 777s.

FAA Administrator Steve Dickson said: “Based on the initial information, we concluded that the inspection interval should be stepped up for the hollow fan blades that are unique to this model of engine, used solely on Boeing 777 airplanes.”

United Airlines said in a tweet: “We are voluntarily & temporarily removing 24 Boeing 777 aircraft powered by Pratt & Whitney 4000 series engines from our schedule. We will continue to work closely with regulators to determine any additional steps and expect only a small number of customers to be inconvenienced.”