Airworthiness Directives; Boeing Model 747-200C and -200F Series Airplanes

The FAA is superseding an existing airworthiness directive (AD), which applies to certain Boeing Model 747-200C and -200F series airplanes. That AD currently requires repetitive inspections to find fatigue cracking in the upper chord of the upper deck floor beams, and repair if necessary. For certain airplanes, the existing AD also provides an optional repair/modification, which extends certain repetitive inspection intervals. This new AD reduces the compliance time for all initial inspections and reduces the repetitive interval for a certain inspection. This AD results from new reports of cracks in the upper deck floor beams occurring at lower flight cycles. We are issuing this AD to find and fix cracking in certain upper deck floor beams. Such cracking could extend and sever floor beams at a floor panel attachment hole location and could result in rapid decompression and loss of controllability of the airplane.