Summary
We propose to supersede Airworthiness Directive (AD) 2013-22- 11, which applies to certain The Boeing Company Model 747-400 and -400D series airplanes. AD 2013-22-11 currently requires repetitive inspections to detect cracks in the floor panel attachment fastener holes of certain upper deck floor beam upper chords, repetitive inspections, corrective actions if necessary, and replacement of the upper deck floor beam upper chords. Since we issued AD 2013-22-11, we received a report that certain fastener holes in the upper deck floor beam upper chords may not have been inspected in accordance with AD 2013-22-11. This proposed AD would add additional repetitive inspections for cracks for certain airplanes, and corrective actions if necessary. We are proposing this AD to detect and correct fatigue cracking in certain upper chords of the upper deck floor beam, which could become large and cause the floor beams to become severed and result in rapid decompression or reduced controllability of the airplane.