FAA to require airlines replace fuel system units on 737 Max

The US FAA has proposed requiring airlines to replace fuel system processors on Boeing 737 Max jets, citing problems with fuel shut-off systems. Boeing already addressed the concern in a 2020 service bulletin that described procedures for replacing a processor unit. The issue involves a problem with the “automatic shut-off system” on 737 Max 8 and Max 9s, says the FAA in a proposed airworthiness directive (AD) issued on 2 April. During refueling, that system is supposed to automatically close a valve when the tank is full. If the automatic shut-off feature fails, the system should generate a flashing warning on the jets’ “refuel panel”, notifying fuel operators of the failure, the FAA says. The agency received reports that the system works improperly during refueling the Max’s right-side tank. Specifically, the system does not flash the warning if the automatic shut-off valve fails to close. The failure is caused by “the flashing threshold in the [fuel quantity processor unit] not being set at the correct fuel level”, the proposed AD says.<br/>