# Proposed AD FAA-2021-0794: The Boeing Company Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2021-26-10
- Products: Boeing
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: October 14, 2021, 86 FR 57081
- Comments due: November 29, 2021
- Became: [AD 2021-26-10](https://openairdocs.org/ad/2021-26-10)
- Docket: FAA-2021-0794 (https://www.regulations.gov/docket/FAA-2021-0794, where comments are filed)
- Project: AD-2021-00400-T
- FR document: 2021-22252
- Official PDF: https://openairdocs.org/files/sha256/b7/61/b76117a0c587787097e1063d0fe71d2f70f9fae0718f1776322b94cb5f8097c7 (from https://www.govinfo.gov/content/pkg/FR-2021-10-14/pdf/2021-22252.pdf)
- Federal Register: https://www.federalregister.gov/documents/2021/10/14/2021-22252/airworthiness-directives-the-boeing-company-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/23A2250647F667148625876E00609674.0001
- Page: https://openairdocs.org/proposed/FAA-2021-0794

## Summary

The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 747-400, -400D, and -400F series airplanes. This proposed AD was prompted by 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. This proposed AD would require replacing the system tube/wire seals made of BMS 8-39 urethane foam in certain areas of the airplane. The FAA is proposing this AD to address the unsafe condition on these products.

## Notices in this docket

- Oct 14, 2021: Notice of proposed rulemaking (NPRM). (first notice), FR document 2021-22252, comments due Nov 29, 2021 (https://www.federalregister.gov/documents/2021/10/14/2021-22252/airworthiness-directives-the-boeing-company-airplanes)

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