NTSB says fan blade wasn’t due for check
Pratt & Whitney engine failed in Feb. flight from Denver
A fan blade that broke on a Pratt & Whitney engine on a United Airlines plane over suburban Denver last month failed long before its next required inspection, federal investigators said Friday.
The blade that fractured, causing the Feb. 20 failure, had 2,979 cycles — with each representing one takeoff and one landing — since its last inspection in 2016, the National Transportation Safety Board said in an investigative update.
The Federal Aviation Administration had ordered that blades on the engine be inspected after 6,500 flights.
Initial examination of the right engine fire damage found it was primarily contained to the engine’ s accessory components, thrust reverser skin and composite structure of the thrust reverse rs.
A valve that stops fuel flow to the engine when the fire switch is pulled in the cockpit was found closed, investigators said. No evidence of a “fuel-fed fire” was found.
Raytheon Technologies Corp., Pratt & Whitney’s Waltham, Massachusetts-based parent company, did not comment, referring questions to the NTSB.
The plane, which was headed to Honolulu with 229 passengers and 10 crew aboard, landed safely at Denver International Airport. No injuries were reported.
Soon after the incident, the FAA ordered stepped-up inspections of Boeing 777 planes equipped with Pratt & Whitney engines. Wear and tear on fan blades may have been a factor in a Pratt & Whitney engine failure aboard a United Airlines flight over Denver, the NTSB said initially.
Apreliminary exam at the scene of fallen debris in Broomfield, Colorado, following the incident found that a fan blade fractured at the root “indicates damage consistent with metal fatigue,” Robert Sumwalt, chairman of the NTSB, said shortly after the incident.
The NTSB report said preliminary findings identified “multiple fatigue fracture origins on the interior surface of a cavity” within the blade.