# Proposed AD FAA-2008-0376: Boeing Model 747-100, 747-200B, 747- 300, and 747SR Series Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2010-05-11
- Products: Boeing
- Product type: Aircraft
- Action: Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.
- Published: September 25, 2009, 74 FR 48882
- Comments due: October 20, 2009
- Became: [AD 2010-05-11](https://openairdocs.org/ad/2010-05-11)
- Docket: FAA-2008-0376 (https://www.regulations.gov/docket/FAA-2008-0376, where comments are filed)
- Project: 2007-NM-322-AD
- FR document: E9-23190
- Official PDF: https://openairdocs.org/files/sha256/8b/ff/8bff26b5d6150b914c455922e2b316cc0f9c41aaf296728d7fa14c791c646619 (from https://www.govinfo.gov/content/pkg/FR-2009-09-25/pdf/E9-23190.pdf)
- Federal Register: https://www.federalregister.gov/documents/2009/09/25/E9-23190/airworthiness-directives-boeing-model-747-100-747-200b-747-300-and-747sr-series-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/7B2877A63EFD772B8625763C0046C977.0001
- Page: https://openairdocs.org/proposed/FAA-2008-0376

## Summary

We are revising an earlier proposed airworthiness directive (AD) for certain Boeing Model 747-100, 747-200B, 747-300, and 747SR series airplanes. The original NPRM proposed to require installation of a closeout panel and moisture curtains for the main equipment center. The original NPRM also proposed to require changing the drain tubes for the power drive units (PDU) and the pitot static tubes and installing larger moisture shrouds. The original NPRM resulted from a report of water contamination in the electrical and electronic units in the main equipment center. This action revises the original NPRM by adding airplanes to the applicability and removing certain others, and removing certain requirements. We are proposing this supplemental NPRM to prevent the malfunction of one or more electrical and electronic units in the main equipment center, which could adversely affect the airplane's continued safe flight.

## Notices in this docket

- Apr 1, 2008: Notice of proposed rulemaking (NPRM). (first notice), FR document E8-6613, comments due May 16, 2008 (https://www.federalregister.gov/documents/2008/04/01/E8-6613/airworthiness-directives-boeing-model-747-100-747-200b-747-300-and-747sr-series-airplanes)
- Sep 25, 2009: Supplemental notice of proposed rulemaking (NPRM); reopening of comment period., FR document E9-23190, comments due Oct 20, 2009 (https://www.federalregister.gov/documents/2009/09/25/E9-23190/airworthiness-directives-boeing-model-747-100-747-200b-747-300-and-747sr-series-airplanes)

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