Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747-100, - 200, and 747-SP series airplanes and military type E-4B airplanes. This proposal would require repetitive inspections to detect cracking of the wing front spar web, and repair of cracked structure. This proposal also provides for optional terminating action for the repetitive inspection requirements. This proposal is prompted by reports indicating that fatigue cracks were found on the aft surface of the wing front spar web. The actions specified by the proposed AD are intended to detect and correct such fatigue cracking, which could result in a fuel leak, and consequent increased risk of a fire.