联邦航空局警告，客机全部两台发动机的第5级止回阀如果都遭腐蚀，可能卡死在打开位置，导致客机完全失去动力且无法重启发动机。
The FAA warned that if the Level 5 check valves in both engines of a passenger airliner become corroded, they may become stuck in the open position, causing the aircraft to completely lose power and be unable to restart its engines.