AD FAA-2013-0625

We are superseding Airworthiness Directive (AD) 94-13-06 for certain The Boeing Company Model 747 series airplanes. AD 94-13-06 required repetitive detailed inspections to detect cracking in certain fuselage upper deck tension ties, repair or modification of any cracked tension ties, and repetitive inspections of repaired and modified tension ties and repair or modification if necessary. AD 94-13-06 also provided for optional terminating action for the repetitive detailed inspections of tension ties that had not been repaired or modified. This new AD retains the repetitive inspections, mandates the previously optional terminating modification, and adds, for tension ties that have not been repaired or modified, repetitive inspections that must be done concurrently with the existing repetitive inspections. This AD was prompted by an evaluation by the design approval holder indicating that the upper deck tension ties of the fuselage are subject to widespread fatigue damage. We are issuing this AD to prevent widespread fatigue damage of certain fuselage upper deck tension ties, which could result in reduced structural integrity of the airplane.