Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 747- 200, -300, and -400 series airplanes, that currently requires inspection of each fuel feed line of the outboard engine in the engine strut to determine if interference with an adjacent pneumatic duct clamp has caused damage, and repair or replacement of the fuel feed tube, if necessary. That AD also currently requires inspection and replacement of the adjacent pneumatic duct clamp with a non-rotating type clamp, if necessary. This action would require modification of the upper gap area of the strut of the number 1 and 4 engines. This proposal is prompted by a report of fuel leakage in the strut of the number 4 engine due to a high profile clamp that chafed the fuel line. The actions specified by the proposed AD are intended to prevent chafing of the fuel line in the strut of the number 1 and 4 engines, which could result in rupture of the fuel line and subsequent in-flight engine fire.