AD 2012-02-09
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Boeing | Company | Airworthiness Directives; The Boeing Company Airplanes |
Unsafe Condition
Airplanes were assembled with air distribution ducts in the environmental control system (ECS) wrapped with BMS 8-39 or AMS 3570 polyurethane foam insulation, whose fire-retardant properties deteriorate with age. This could lead to ignition of the insulation due to a potential electrical arc, starting a small fire that may spread throughout the airplane via the ECS.
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Required Actions
Rework the applicable duct assemblies in the ECS within 72 months after the effective date, in accordance with Boeing Service Bulletin 737-21A1132, Revision 3. As of the effective date, no ECS duct assembly with BMS 8-39 or AMS 3570 insulation may be installed.
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Compliance Time
Within 72 months after the effective date of March 13, 2012.
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Affected Aircraft
The Boeing Company Model 737-100, -200, -200C, and -300 series airplanes, certificated in any category, as identified in Boeing Service Bulletin 737-21A1132, Revision 3.
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Source: Official FAA Source ↗
Retrieved: Apr 6, 2026
Rights: U.S. Government Public Domain
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