The Federal Aviation Administration (FAA) has issued an Emergency Airworthiness Directive (AD) for around 2,000 U.S.-registered Boeing 737 NG and Classic aircraft.
According to the FAA, this announcement was generated after four recent reports of single-engine shutdowns; caused by engine purge air 5th stage check valves stuck in open position.
“Corrosion of the internal parts of the 5th stage check valve of engine purge air during airplane storage can cause the valve to stick in the open position.”
 100vw, 800px “/><figcaption>Southwest Airlines B737</figcaption></figure>
<p data-birdsend-par-index=)
In the worst case, corrosion of these valves on both engines could result in dual engine failure; this would leave the aircraft without the ability to restart, and consequently could cause a forced landing outside the airport.
This AD is valid for any 737 NG (600 to 900 series) and 737 Classic (737-300 to 737-500 series) that, for 7 or more consecutive days, has not been operated in flight or is considered to be in “storage .
In the United States, several airlines operate this type of aircraft; including United Airlines, Delta, Southwest Airlines and American Airlines. The B737 MAX remains grounded.
