AD 2021-26-10
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Boeing | Company | Airworthiness Directives; The Boeing Company Airplanes |
Unsafe Condition
Reports of burned Boeing Material Specification (BMS) 8-39 urethane foam, and a report from the airplane manufacturer that airplanes were assembled with seals throughout various areas of the airplane (including flight deck and cargo compartments) made of BMS 8-39 urethane foam, a material with fire-retardant properties that deteriorate with age.
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Required Actions
Replace the BMS 8-39 urethane foam seals in the forward cargo compartment system tube/wire (including doing a general visual inspection of the foam for any tube or wire penetrations and sealing any penetrations that go through the insulation blankets) with BMS 1-68 silicone foam rubber seals, as applicable, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-25-3381, Revision 3, dated February 19, 2021.
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Compliance Time
Within 72 months after the effective date of this AD
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Affected Aircraft
The Boeing Company Model 747-400, -400D, and -400F series airplanes, certificated in any category, identified as Group 11, Configuration 2; Group 13 and 14, Configuration 4; and Group 16, 17, and 19, Configuration 5, in Boeing Special Attention Service Bulletin 747-25-3381, Revision 3, dated February 19, 2021.
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Source: Official FAA Source ↗
Retrieved: Apr 4, 2026
Rights: U.S. Government Public Domain
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