Transport i infrastruktura · 15/12/1994

Airworthiness Directives; Boeing Model 727 and Model 737 Series Airplanes

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 727 and Model 737 series airplanes. This proposal would require replacement of the actuator of the engine fuel shutoff valve and the fuel system crossfeed valve with an improved actuator. This proposal is prompted by reports indicating that, during ground acceptance tests on Model 737 series airplanes, the actuator clutch on the engine shutoff and crossfeed valves slipped at cold temperatures due to improper functioning. The actions specified by the proposed AD are intended to prevent improper functioning of these actuators, which could result in a fuel imbalance due to the inability of the flightcrew to transfer fuel through the crossfeed valve; improperly functioning actuators could also prevent the pilot from shutting off the fuel to the engine following an engine failure and/or fire.