Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747-100 and - 200 series airplanes. This proposal would require repetitive inspections of the upper and lower chords of the wing front spar for cracks, and corrective action, if necessary. For airplanes on which no cracking is detected, this proposal would also provide optional terminating action in lieu of repetitive inspections. This proposal is prompted by reports of cracks in the upper chord of the wing front spar. The actions specified by the proposed AD are intended to detect and correct fatigue cracking of the upper and lower chords of the wing front spar, which could result in reduced structural capability and possible fuel leakage onto an engine and a resultant fire.