The FAA issued an emergency AD affecting more than 2,000 second- and third-generation Boeing 737s that have been parked since the COVID-19 pandemic took hold in March. The AD requires immediate inspection of the fifth stage bleed air check valve to check for corrosion. The corroded valves don’t close after the engine is throttled back from climb power. "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 said in a news release. "Corrosion of these valves on both engines could result in a dual-engine power loss without the ability to restart.”
This is a companion discussion topic for the original entry at https://www.avweb.com/aviation-news/emergency-ad-affects-2000-stored-737s