AD 91-08-12
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 737-100 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-200 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-200C Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-300 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-400 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-500 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-600 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-700 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
| aircraft | The Boeing Company | 737-800 Series | Airworthiness Directives; BOEING Model 737 Series Airplanes |
Unsafe Condition
Disbonded doublers and corrosion/cracks in lap splices and stringer S-17 could cause inability to carry fail-safe loads and rapid decompression.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Perform a one-time external ultrasonic inspection within 60 calendar days after May 17, 1991. If disbonding is found, conduct HFEC and visual inspections for cracks/corrosion, repair as needed, and install oversize protruding head solid fasteners within specified flight cycles. Repeat inspections at intervals not exceeding 4,500 flight cycles or 15 months, whichever comes first. Replace blind fasteners with solid fasteners within 10,000 flight cycles.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 60 calendar days after the effective date of this AD (May 17, 1991) for the initial inspection. Subsequent actions must be done prior to further flight or within specified intervals (e.g., 4,500 flight cycles, 15 months, 3,000 flight cycles, 10,000 flight cycles).
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Boeing Model 737 series airplanes, line numbers 520 through 610.
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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