AD 91-05-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 747-400 Series | Airworthiness Directives; BOEING Model 747-400 Series Airplanes |
Unsafe Condition
Cross connection of fire extinguishing wiring during maintenance could lead to failure of the engine fire extinguishing system.
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Required Actions
Modify the engine fire extinguishing system or fire control module in accordance with specified Boeing Service Bulletins. An alternate means of compliance or adjustment may be approved by the FAA. Special flight permits may be issued under FAR 21.197 and 21.199.
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Compliance Time
within the next 12 months after the effective date of this AD, unless previously accomplished
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Affected Aircraft
Model 747-400 series airplanes listed in Boeing Service Bulletins 747-26-2138 (Rev 1, March 1, 1990) and 747-26-2141 (Rev 1, July 12, 1990)
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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