AD 2008-14-14
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Boeing | 747-400 and 747-400D | Airworthiness Directives; Boeing Model 747-400 and 747-400D Series Airplanes |
Unsafe Condition
Insufficient clearance between the power feeder wire bundle of the auxiliary power unit (APU) and the hydraulic system 4 return tube, leading to potential chafing, arcing, and a hydraulic fluid fire outside the smoke detection and fire extinguishing zone.
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Required Actions
Perform a general visual inspection of the power feeder wire bundle of the APU where it crosses the hydraulic system 4 return tube to determine if parts are installed to provide separation. Accomplish all related investigative and corrective actions as specified in Boeing Special Attention Service Bulletin 747-24-2257, Revision 1, dated August 2, 2007. Complete all corrective actions before further flight after the inspection.
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Compliance Time
Within 24 months after the effective date of August 21, 2008.
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Affected Aircraft
Boeing Model 747-400 and 747-400D series airplanes, certificated in any category, as identified in Boeing Special Attention Service Bulletin 747-24-2257, Revision 1, dated August 2, 2007.
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Source: Official FAA Source ↗
Retrieved: Apr 4, 2026
Rights: U.S. Government Public Domain
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