The National Transportation Safety Board revealed that the right engine failed a few minutes after takeoff from Denver airport, when the pilots of the aircraft accelerated the engines “to minimize the time in the expected turbulence.”
“Immediately after the accelerators were advanced, there was a loud bang” on the cabin’s voice recorder, CNN reported.
The new details are part of an update from the NTSB in its ongoing investigation, which usually takes a year or more to complete. The seven-page report did not draw any conclusions about the cause of the incident, nor did it prescribe further steps for the federal aviation administration, aircraft operators or the engine manufacturer.
A warning light indicated an engine fire, according to the update. The pilots followed a firefighting procedure and determined that they would not throw fuel to make the aircraft lighter before landing. They concluded that “the extent of the overweight landing was not significant enough to go beyond other considerations,” the NTSB said.
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The report said that a valve that interrupts the flow of fuel to the engine in the event of a fire has closed properly and said “there is no evidence of a fuel-fired fire”. The report mentions the deterioration of “fuel, oil and hydraulic lines”.
The plane returned safely to Denver International Airport without injuries on board or on the ground, where the wreckage of the plane rained in a residential area of Broomfield, Colorado. The report said the engine caught fire after landing, but was “quickly extinguished” by firefighters.
The NTSB report showed that the failed fan blade was inspected using specialized acoustic thermal imaging technology in both 2014 and 2016. The inspection looks for small cracks or signs of metal fatigue that may not be visible to the naked eye. free.
After a 2018 engine incident on another plane, 2016 data was analyzed again, NTSB said.
The report noted that when the fan blade failed last month, it was less than halfway to the point of requiring another inspection – a detail previously reported by CNN. 2,979 cycles had been operated, an approximate measure of the number of times the engine was started and stopped. The inspection was required after 6,500 cycles.
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A few days after the February incident, engine maker Pratt & Whitney recommended dramatically reducing the inspection interval to just 1,000 cycles, according to a CNN service bulletin. The FAA issued an emergency directive requiring the inspection of fan blades on engines before flying again.
The inspection interval for this series of engines has been a concern for federal regulators. CNN previously reported that a Federal Aviation Administration review committee met just days before the February engine failure to consider the need for more regular inspections.
Due to the engine failure, Boeing recommended suspending the use of 777s that have the Pratt & Whitney 4000 engine, and United Airlines has already removed its 777s following the incident. Both the FAA and the NTSB are investigating.
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