# Airworthiness Directives; The Boeing Company Airplanes
> **Rule** · Final rule. · Published 2012-02-07 · Effective 2012-03-13 · 77 FR 5996
## Document
- **Document number:** 2012-2004
- **Category:** airworthiness
- **Manufacturer:** The Boeing Company
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 77 FR 5996
- **Publication date:** 2012-02-07
- **Effective date:** 2012-03-13
- **FAA docket:** Docket No. FAA-2011-1171
## Abstract

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-100, -200, -200C, and -300 series airplanes. This AD was prompted by a report from the airplane manufacturer that airplanes were assembled with air distribution ducts in the environmental control system (ECS) wrapped with Boeing Material Specification (BMS) 8-39 or Aeronautical Materials Specifications (AMS) 3570 polyurethane foam insulation, a material with fire-retardant properties that deteriorate with age. This AD requires reworking certain air distribution ducts in the ECS. We are issuing this AD to prevent ignition of the BMS 8-39 or AMS 3570 polyurethane foam insulation on the duct assemblies of the ECS due to a potential electrical arc, which could start a small fire and lead to a larger fire that may spread throughout the airplane through the ECS.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2012/02/07/2012-2004/airworthiness-directives-the-boeing-company-airplanes)
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