AD 2021-14-10
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Boeing | Company | Airworthiness Directives; The Boeing Company Airplanes |
Unsafe Condition
degraded BMS 8-39 urethane foam used in seals, which may fail to maintain sufficient halon concentrations in the cargo compartments to extinguish or contain fire or smoke, and may fail to prevent penetration of fire or smoke in areas of the airplane that are difficult to access for fire and smoke detection or suppression, which could result in loss of control of the airplane.
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Required Actions
Inspect the insulation blankets in the area between station (STA) 960 and STA 1000 on the left and right sides of the forward cargo compartment for exposed BMS 8-39 urethane foam, not encapsulated by a protective fire resistant barrier, and seal integrity, and replacing any BMS 8-39 urethane foam that is found exposed and any seal that does not have acceptable integrity for a smoke barrier.
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Compliance Time
Within the compliance times specified in the "Compliance" paragraph of Boeing Special Attention Requirements Bulletin 747-25-3725 RB, dated October 27, 2020
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Affected Aircraft
The Boeing Company Model 747-400, 747-400D, and 747-400F series airplanes, certificated in any category, as identified in Boeing Special Attention Requirements Bulletin 747-25-3725 RB, dated October 27, 2020.
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Source: Official FAA Source ↗
Retrieved: Apr 4, 2026
Rights: U.S. Government Public Domain
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