Airworthiness Directives; Boeing Model 747-100 and −200 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-100 and -200 series airplanes, that requires 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 AD also provides an optional terminating action in lieu of repetitive inspections. This amendment is prompted by reports of cracks in the upper chord of the wing front spar. The actions specified by this 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.