Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747-100, - 200, -300, and -400 series airplanes. This proposal would require a one-time visual inspection to determine the part number of the fuel shutoff valve installed in the outboard engines. The proposed AD also would require replacement of certain valves with new valves, or modification of the spar valve body assembly, 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 on in-service airplanes. 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.