(Reuters) – The US Federal Aviation Administration on Friday issued an emergency airworthiness directive for 2,000 US-registered Boeing 737 NG and Classic aircraft, warning of possible corrosion on parked aircraft that could lead to a double engine failure.  Inspectors found compromised air control valves when disembarking aircraft after four recently reported shutdowns of single-engine on parked aircraft, leading to the directive for aircraft not running for seven or more consecutive days.
Alaska Airlines said one of its aircraft is likely to be one of four incidents and notes a new engine shutdown issue.
"Flight safety was not compromised," Alaska said in a statement, adding that it now inspects the check valves before returning aircraft to
If airlines find corrosion, they must replace the valve before flying again, the FAA said.
Boeing Co. said on Friday that it had informed operators to inspect the plane and added "with aircraft stored or rarely used due to lower demand during the COVID-1
Global airlines parked thousands of aircraft after the coronavirus pandemic sharply reduced travel demand but some have started flying again when demand picks up.
The FAA said that the directive is to deal with corrosion of the engine exhaust air 5-stage check valves for both engines. The agency said it could lead to compressor booths and loss of power with twin engines without the ability to restart.
Boeing said it provides inspection and replacement information to fleet owners if they find a problem.
Among other US carriers of 737, American Airlines and Southwest Airlines said that they follow the directive but had not experienced any problems.
United Airlines and Delta Air Lines also said they follow and do not anticipate any impact on operations.