Airworthiness Directives; Boeing Model 747 Series Airplanes

This amendment supersedes 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 amendment adds new requirements to accomplish those actions on additional airplanes; and requires 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 amendment 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 this 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.