The investigation into an engine explosion on a jetliner taking off from Denver is focusing on a fan blade that appeared to be weakened by wear and tear, a development reminiscent of a fatal failure on board another plane in 2018.
These and other recent engine failures raise questions over long-held assumptions about how long fan blades last and whether they are being inspected often enough.
A Boeing 777 operated by United Airlines had to make an emergency landing in Denver after one of its engines blew apart, spewing huge chunks of wreckage that landed in neighborhoods and sports fields. Passengers captured video of the crippled engine, wobbling and still on fire, as pilots made a safe return to the airport minutes after the plane bound for Hawaii took off.
Investigators said late Monday that two fan blades in the Pratt & Whitney engine broke off and one of them showed signs of metal fatigue, or hairline cracks from the stress of wear and tear. They believe the weakened blade broke off first, then chipped off half of an adjacent blade.
Robert Sumwalt, chairman of the National Transportation Safety Board, said the agency’s investigators will examine maintenance records for the engine and fan blades. He said fan blade pieces — including one found on a soccer field in a Denver suburb — will be examined Tuesday in a Pratt & Whitney laboratory.
Federal Aviation Administration head Stephen Dickson said inspectors quickly determined that inspections should be done more frequently for the type of hollow fan blades in certain Pratt & Whitney engines that are used on some Boeing 777s.
As a result, 69 planes and another 59 in storage were grounded in the U.S., Japan and South Korea, the only countries with planes using this particular engine. United, the only U.S. carrier with affected planes, said it grounded 24 Boeing 777s and 28 others will remain parked. Japanese regulators ordered Japan Airlines and All Nippon Airways to ground 32 planes, and South Korea’s Korean Air and Asiana Airlines said Monday they will ground their Boeing 777s.
Source: Associated Press – DAVID KOENIG