Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that currently requires a one-time inspection to determine the part number of the fuel shutoff spar valve for the outboard engines. That AD also requires replacement of certain valves with new valves, or modification of the spar valve body assembly, and various follow-on actions. This action would add new requirements to accomplish those actions on additional airplanes; and would require a one-time inspection of the maintenance records of certain airplanes to determine if the fuel shutoff spar valve for the outboard engines has ever been replaced, and various follow-on actions. This proposal is prompted by reports indicating that, due to high fuel pressure, certain fuel system components of the outboard engines have failed. The actions specified by the proposed AD are intended to prevent such high fuel pressure, which could result in failure of the fuel system components; this situation could result in fuel leakage, and, consequently, lead to an engine fire.