Following four recent reports of single-engine shutdowns, the Federal Aviation Administration (FAA) issued an order on July 23 requiring operators of Boeing 737s to inspect a potentially faulty engine component that could result in stalls and dual-engine power loss.
The Emergency Airworthiness Directive (AD) was sent to owners and operators of model 737 planes that have not been flown in at least a week on or after July 23, or has been operating for 10 or fewer flights since returning to service. The AD applies to the following 737 models: 737-300, -400, -500, -600, -700, -800, -900, and -900ER series.
The engine issue stems from a valve becoming stuck. Corrosion of internal parts of what is called the "engine bleed air 5th stage check valve" during storage may cause the valve to become stuck in the open position, according to the FAA.
"If this valve opens normally at takeoff power, it may become stuck in the open position during flight and fail to close when power is reduced at top of descent, resulting in an unrecoverable compressor stall and the inability to restart the engine," the FAA wrote in the AD.
Corrosion of the valves on both engines could lead to "dual-engine power loss without the ability to restart."
If the faulty engine component is not addressed, the FAA said it could result in a "forced off-airport landing."