NEW YORK • More than 100 Boeing 777 planes were grounded worldwide following a weekend scare on a United Airlines (UA) plane which suffered engine failure and scattered airplane debris over suburban Denver in Colorado.
The incident last Saturday on the flight out of Denver - which quickly returned to the airport after part of the engine caught fire and broke off - prompted UA and other airlines to ground planes with the same Pratt & Whitney (P&W) engine.
Boeing said all 128 of the 777s with the engines were grounded following the emergency landing of Flight 328 to Hawaii.
Besides UA, which removed 24 planes from service, affected airlines include Japanese carriers Japan Airlines and All Nippon Airways, and South Korean carriers Asiana and Korean Air.
United States National Transportation Safety Board (NTSB) chairman Robert Sumwalt said on Monday that damage to a fan blade in the P&W engine is consistent with metal fatigue, according to a preliminary assessment.
The UA engine's fan blade was examined yesterday under supervision of NTSB investigators after being flown to a P&W laboratory.
The Federal Aviation Administration (FAA) plans to issue an emergency airworthiness directive soon that will require stepped-up inspections of P&W fan blades for fatigue.
FAA chief Steve Dickson said a preliminary safety data review pointed to a need for additional checks of the jet engine's fan blades, which were unique to the model and used only on 777 planes.
A video shot from inside Flight 328 showed the right engine ablaze and wobbling on the wing of the Boeing 777-200.
Residents in the Denver suburb of Broomfield found large pieces of the plane scattered around their community.
While no one was injured in the Denver incident, the episode is the latest setback for Boeing, which only recently resumed deliveries of its long-grounded 737 Max following two fatal crashes.
Aviation experts said the incident especially raised questions about P&W and UA over engine maintenance.
The incident follows a Japan Airlines Boeing 777 incident in December last year involving the same type of engine, as well as an engine problem in February 2018 on another UA flight.
The company also faces a fresh investigation in Holland after a Boeing 747-400 cargo plane showered the small town of Meerssen with debris, injuring two people - the same day as the engine failure in Denver.
Aerospace consultant Michel Merluzeau said the latest problem did not appear to result from poor plane design by Boeing. "It's not really a problem for Boeing. It's more an issue of maintenance - how United Airlines or Pratt & Whitney is maintaining engines that have been in use for a while."
Mr Scott Hamilton, managing director of Leeham News, an aviation news site, said the episode "is an embarrassing headline, but as a practical issue, it will have no impact on Boeing".
Noting the weak demand for longer-service planes amid the global pandemic, Mr Hamilton predicted some of the carriers could opt to retire the planes rather than return them to service.
Shares of Boeing fell 2.1 per cent to US$212.88 yesterday, while those of P&W's parent company Raytheon Technologies fell 1.7 per cent to US$73.
UA rose 3.5 per cent to US$49.70, joining other carriers in rallying after a positive note from Deutsche Bank about the sector's prospects amid improving Covid-19 trends.
AGENCE FRANCE-PRESSE, REUTERS