The Federal Aviation Administration ordered airlines to inspect the engines of their 737 aircraft after four reports of “single-engine shutdowns.”
Many 737 aircraft have been sitting in hangars for weeks, as the coronavirus pandemic suppressed demand for air travel. As airlines resumed operations, they discovered that a key valve tends to get stuck after weeks without being used. The FAA estimates that around 2,000 aircraft could be affected.
“If this valve opens normally at takeoff power, it can get stuck in the open position during flight and not close when power is reduced at the top of the descent,” the FAA directive warns. That could result in “unrecoverable compressor shutdown and inability to restart the engine.”
This has happened four times in the past few weeks. Alaska Airlines has acknowledged that one of its planes suffered the problem during a flight from Seattle to Austin. The plane was able to land safely despite the unexpected shutdown of one of its engines, and no one was injured, the airline says.
Fortunately, the same was true for the other three incidents – only one engine was shut down and no injuries occurred as a result. But the FAA fears that an aircraft could suffer the same malfunction in both engines simultaneously, which could “result in a forced landing outside the airport.”
So the FAA is directing airlines to carefully inspect the engines of any 737 aircraft that has been out of service for seven or more days in a row, and that has not flown 10 times since then. If a sticky valve is discovered, it must be replaced before the aircraft can be returned to service. Most airlines said the mandatory inspections would not significantly affect their flight schedules.
The order refers to previous 737 models, from line 737-300 to line 737-900. Boeing’s new 737-MAX line is still grounded as the company struggles to remedy design and software problems.
