The US Federal Aviation Administration (FAA) has ordered inspections of around 2,000 Boeing 737 NGs and Classics that had not flown for at least seven days after identifying issues on valves that could lead to engine failure.
With planes “parked on the ground or used less frequently” because of the COVID-19 pandemic, affected valves may be “more susceptible to corrosion,” Boeing acknowledged. The manufacturer has already advised customers with these 737s to inspect them.
Planes are usually subjected to a thorough examination when they are about to take off after several days of standstill.
The FAA says it has ordered more specific inspections on the 737 NG and 737 Classic after “four recent reports of engine failures related to control valves stuck in the open position. If this valve opens normally at take-off power, it may get stuck in the open position during flight and not close when power is reduced at the start of the descent, causing the compressor to stall irreversibly and the impossibility to restart the engine. This could ultimately lead to an emergency landing.”
Also “if corrosion is found” during the inspection, “the valve should be replaced before the aircraft is returned to service,” the agency said.
Boeing said it was ready to provide information on inspections and possible part replacements if the owners of the affected aircraft spotted a problem.