AD 2007-10-09
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Boeing | 747-400 | Airworthiness Directives; Boeing Model 747-400 Series Airplanes |
Unsafe Condition
Fatigue cracking in the upper deck floor beam at station 400, made from 7000 series aluminum alloy, could extend and sever the floor beam, resulting in loss of controllability and rapid decompression of the airplane.
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Required Actions
Inspect the upper deck floor beam web and chords, certain fastener holes at the intersection of the floor beam and frame on both sides of the airplane, and certain floor panel attachment fastener holes at the floor beam upper chords for any crack. If a crack is found, contact Boeing for repair instructions. Oversize cracked fastener holes and perform open hole HFEC inspections of the oversized holes if necessary. Install an oversized fastener if no crack is found and a minimum edge margin of 1.7D is maintained. If a crack cannot be removed by oversizing, contact Boeing for repair instructions.
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Compliance Time
Before the airplane has accumulated 18,000 total flight cycles. Repetitive inspections are required at intervals of 10,000 flight cycles for certain inspections and 6,000 flight cycles for others.
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Affected Aircraft
Boeing Model 747-400 series airplanes with upper deck floor beams made from 7000 series aluminum alloy, specifically those identified as having the discrepant floor beams at station 400.
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Source: Official FAA Source ↗
Retrieved: Apr 4, 2026
Rights: U.S. Government Public Domain
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