Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 777-200, -200LR, -300, and -300ER series airplanes. This proposed AD was prompted by a report indicating that the manufacturer discovered locations where the control components and wiring of the left and right engine fuel spar valves do not have adequate physical separation to meet the redundant system separation requirements. This proposed AD would require modifying the wiring, and installing a new relay bracket and new location for the relay on the left and right engine fuel spar valves. This proposed AD would also require an inspection to identify the part number of the motor operated valve (MOV) actuators for the left and right engine fuel spar valves; replacement of specified MOV actuators with new MOV actuators; certain bonding resistance measurements; and applicable corrective actions. We are proposing this AD to prevent loss of control of both the left and right engine fuel sparvalves during a single event, such as local wire bundle damage or a wire bundle fire, which could cause both engines to shut down or result in the inability to control an engine fire.