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FAA issues emergency AD on Boeing 737 fuel pump wiring
19 November 2008

The FAA issued an emergency Airworthiness Directive (AD) to certain owners and operators of Boeing 737-600,-700,-700C,-800, and -900 series airplanes.
Information indicates that, when the flightcrew manually turns off the center wing tank (CWT) pump switches, that action turns off the right-hand pump, but re-energizes the left-hand pump due to incorrect wiring. The low-pressure lights turn off, incorrectly indicating to the flightcrew that power to both pumps has been removed. The failure condition results in continual running of the left-hand fuel pump without indication to the flightcrew, which could lead to localized
overheating of parts inside the fuel pump, and which could produce an ignition source inside the fuel tank.
The FAA requires the operators of aircraft effected to carry out a wiring test as specified in the AD. (FAA)