DENVER (AP) – The Federal Aviation Administration on Tuesday ordered U.S. airlines to land a plane with the engine that blew off after flying over Denver over the weekend before they could check for stress cracks.
The FAA order applies to some US aircraft operators, including Pratt & Whitney PW4000 engines, which are used exclusively on Boeing 777 aircraft. Operators must check the thermal acoustic image of the large titanium fan blades on the front of each engine before re-launching the aircraft.
The technology can detect cracks in the inner surfaces of hollow blades that are not visible to the naked eye on demand.
The FAA order is a blow to United Airlines, which operated 24 aircraft – the only American airline to have an engine with its own engine.
“On Sunday, we voluntarily removed a Boeing 777 powered by a Pratt & Whitney 4000 engine from our schedule,” said David Gonzalez, a spokesman for United. “We have worked with the NTSB to investigate whether we will comply with the FAA Emergency Aviation Directive to ensure that all 52 aircraft affected by our fleet meet our strict safety standards.”
The Denver-Honolulu flight from the United States made an emergency landing shortly after takeoff on Saturday when parts of the engine casing rained down on suburban areas. None of the 231 passengers or 10 crew members were injured և The flight landed safely.
The chairman of the National Transportation Safety Council, Robert Sumwalt, told a virtual news conference Monday evening that a broken fan blade found in the engine showed signs of “damage due to metal fatigue”. According to the preliminary investigation, the broken blade touched the broken blade as the engine split.
Sumwalt said the broken knife was first flown by private jet to Pratt & Whitney headquarters Monday night for examination by NTSB investigators.
“Our mission is to understand not only what happened, but why it happened so that we can avoid it happening again,” he said.
The FAA directive states that the agency will review the results of inspections “on a rolling stock basis”.
“Based on the preliminary results of their receipt, as well as other data obtained as a result of the ongoing investigation, the FAA may revise this instruction to establish a new break for this or subsequent inspections,” the order said.
For Pratt & Whitney PW4000 engines, the previous test interval was 6,500 flight cycles. The flight cycle is defined as one flight: landing.
A video posted on Twitter on Saturday about the emergency situation shows that the engine ignites completely while the plane is flying. The freezing frames of various videos made by a passenger sitting on the front of the engine և on Twitter seem to show the blade of a broken engine fan.
The passengers said that they were afraid that the plane would crash after the explosion, when the light shone, while the people sitting on the ground saw that huge pieces of the plane were falling, they just missed one house, smashed the truck. A visible explosion from the ground left a trail of black smoke in the sky.