AD 58-20-03
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Lockheed Aircraft Corporation | 149-46 | LOCKHEED Models 049, 149, 649, 649A, 749, and 749A Aircraft |
| aircraft | Lockheed Aircraft Corporation | 49-46 | LOCKHEED Models 049, 149, 649, 649A, 749, and 749A Aircraft |
| aircraft | Lockheed Aircraft Corporation | 649-79 | LOCKHEED Models 049, 149, 649, 649A, 749, and 749A Aircraft |
| aircraft | Lockheed Aircraft Corporation | 649A-79 | LOCKHEED Models 049, 149, 649, 649A, 749, and 749A Aircraft |
| aircraft | Lockheed Aircraft Corporation | 749-79 | LOCKHEED Models 049, 149, 649, 649A, 749, and 749A Aircraft |
| aircraft | Lockheed Aircraft Corporation | 749A-79 | LOCKHEED Models 049, 149, 649, 649A, 749, and 749A Aircraft |
Unsafe Condition
Severe corrosion in the aft pressure bulkhead area of the lavatories, which resulted in an in-flight failure.
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Required Actions
Inspect the aft side of the pressure bulkhead (Station 1037) and adjacent shell structure between stringers 24 and 48 within 50 flight hours. If corrosion is found, immediately inspect both sides of the bulkhead and surrounding areas by removing toilets, trim, insulation, etc., within 200 flight hours. Repair corroded parts, clean, apply inhibitor, reseal, and repaint. Repeat inspections every 4,000 hours or at block overhauls, extendable to 8,000 hours with equivalent sealing/drainage per SB-597. Limit cabin pressure to 2 p.s.i. until inspections are done.
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Compliance Time
Compliance required as indicated.
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Affected Aircraft
Lockheed Models 049, 149, 649, 649A, 749, and 749A Aircraft with serial numbers 1963-1980, 2021-2088, 2501-2631, 2633-2638, and 2640.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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