NTSB Prepares To Analyze Debris from United 777 Engine Failure

 - February 21, 2021, 9:18 AM

Investigators from the National Transportation Safety Board have begun collecting debris from the United Airlines Boeing 777-200 that suffered an engine failure over a mile-long area of a Denver suburb Saturday afternoon. The engine failure, involving a Pratt & Whitney PW4077 turbofan, happened soon after United Flight 328 took off from Denver International Airport on its way to Honolulu. The airplane turned around and safely landed in Denver at about 1:30 pm. None of the 241 passengers and crewmembers nor anyone on the ground suffered injuries.

Television footage showed a nearly intact nacelle inlet lip from the PW4077 lying in the front yard of a suburban home in Broomfield, Colorado, roughly 30 miles west of the airport. More large engine cowl pieces landed at a nearby athletic field. Cell phone video footage taken by passengers in the airplane showed nearly the entire cowling from the right engine missing while the engine itself spewed flames from its core.    

An almost identical incident in 2018 also involved a United Airlines Boeing 777-200 on approach to Honolulu. In that case, the cowling surrounding the right PW4077 fell off some 45 minutes before the airplane landed. Investigators found that a fractured fan blade caused that failure. Last year the NTSB determined that insufficient training for a thermal acoustic imaging (TAI) inspection process developed by Pratt & Whitney led to technicians misdiagnosing a problem with the fan blade that ultimately failed in the 2018 incident. Since then Pratt developed a formal training curriculum for the inspections and the FAA issued an airworthiness directive in March 2019 requiring repetitive inspections of all PW4000s in service.