Denver, Colorado 2021-02-23 23:08:27 –
On Tuesday, the Federal Aviation Administration ordered US airlines to ground an airplane with an engine of the type that exploded after taking off from Denver last weekend until it could be inspected for stress cracks. ..
The FAA’s orders apply to US operators of airplanes equipped with certain Pratt & Whitney PW4000 engines used only on the Boeing 777. Before the plane flies again, the operator must perform a thermoacoustic imaging of the large titanium fan blades at the front of each engine.
This technique can sequentially detect cracks on the inner surface of the hollow blade that are invisible to the naked eye.
The FAA Directive is a blow to United Airlines, the only US airline with engines in its fleet, with 24 planes in service.
“On Sunday, we voluntarily removed 24 Boeing 777 aircraft with Pratt & Whitney 4000 series engines from the schedule,” said United spokesman David Gonzalez. “We are working with the NTSB to ensure that all 52 affected aircraft in the fleet meet strict safety standards in compliance with the FAA’s Emergency Airworthiness Directive. . “
United Airlines from Denver to Honolulu made an emergency landing shortly after takeoff on Saturday as debris from the engine casing rained in the suburban neighborhood. Neither the 231 passengers nor the 10 crew members were injured and the flight landed safely.
National Transportation Safety Board Chairman Robert Samwalt said at a virtual press conference on Monday night that fan blade damage found in the engine had visible signs of “damage consistent with metal fatigue.” It was. According to preliminary research, the broken blade smashed into the next blade when the engine broke.
The first destroyed blade was shot by a private jet to Pratt & Whitney’s headquarters on Monday night and inspected under the supervision of an NTSB investigator, Samwalt said.
“Our mission is to understand not only what happened, but why it happened, and prevent it from happening again,” he said.
The FAA directive said authorities would review the results of the test “on a rolling basis.”
“Based on the initial results we received, and other data obtained from ongoing investigations, the FAA may revise this directive to set new intervals for this or subsequent inspections. I am following the instructions.
The previous inspection interval for the Pratt & Whitney PW4000 engine was 6,500 flight cycles. A flight cycle is defined as a single takeoff and landing.
A video posted on Twitter from a Saturday emergency showed that the engine was completely in flames when the plane flew. Another video freeze frame shot by a passenger sitting shortly before the engine and posted on Twitter seemed to indicate that the engine fan blades were broken.
Passengers said they were worried that the plane would crash after the explosion and flash. Meanwhile, people on the ground saw a huge chunk of aircraft pouring down, losing a house and crushing a truck. The explosion seen from the ground left a mark of black smoke in the sky.
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