AD 99-06-18
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | The Boeing Company | 747-400 Series | Airworthiness Directives; BOEING Model 747-400, -400D, and -400F Series Airplanes |
| aircraft | The Boeing Company | 747-400D Series | Airworthiness Directives; BOEING Model 747-400, -400D, and -400F Series Airplanes |
| aircraft | The Boeing Company | 747-400F Series | Airworthiness Directives; BOEING Model 747-400, -400D, and -400F Series Airplanes |
Unsafe Condition
Loss of control of the cabin pressurization system due to a single failure of the auxiliary power unit (APU) battery, which could result in rapid depressurization of the airplane.
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Required Actions
Modify the P212 and P213 panels of the cabin pressure control system. For certain airplanes, also modify the P5, P6, and P7 panels, and the W4701, W4703, and W4908 wire bundles as applicable.
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Compliance Time
Within 12 months after the effective date of this AD (April 26, 1999).
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Affected Aircraft
Boeing Model 747-400, -400D, and -400F series airplanes identified in Boeing Alert Service Bulletin 747-21A2381.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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