AD 90-26-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 747-400 Series | Airworthiness Directives; BOEING Model 747-400 Series Airplanes |
Unsafe Condition
Failure of the fire detection warning system to annunciate a fire.
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Required Actions
Modify the wiring of the aural and master warning indication systems of the fire detection system in accordance with Boeing Alert Service Bulletin 747-26A2171, dated October 4, 1990. An alternate means of compliance or adjustment of the compliance time may be used when approved by the FAA.
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Compliance Time
Within 45 days after the effective date of this airworthiness directive, unless previously accomplished.
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Affected Aircraft
Boeing Model 747-400 series airplanes listed in Boeing Alert Service Bulletin 747-26A2171, dated October 4, 1990, certificated in any category.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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