Summary
This document revises an earlier proposed airworthiness directive (AD), applicable to certain Boeing Model 727 and Model 737 series airplanes, that would have required replacement of the actuator of the engine fuel shutoff valve and the fuel system crossfeed valve with an improved actuator. That proposal was prompted by reports indicating that, during ground acceptance tests on Model 737 series airplanes, the actuator clutch on the engine shutoff and [[Page 16389]] crossfeed valves slipped at cold temperatures due to improper functioning. This action revises the proposed rule by expanding the applicability to include an additional actuator. The actions specified by this proposed AD are intended to prevent improper functioning of these actuators, which could result in a fuel imbalance due to the inability of the flight crew to crossfeed fuel; improperly functioning actuators could also prevent the pilot from shutting off the fuel to the engine following an engine failure and/or fire.