# Proposed AD FAA-2010-0856: the Boeing Company Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2012-21-08
- Products: Boeing
- Product type: Aircraft
- Action: Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.
- Published: May 30, 2012, 77 FR 31758
- Comments due: July 16, 2012
- Became: [AD 2012-21-08](https://openairdocs.org/ad/2012-21-08)
- Docket: FAA-2010-0856 (https://www.regulations.gov/docket/FAA-2010-0856, where comments are filed)
- Project: 2010-NM-117-AD
- FR document: 2012-13028
- Official PDF: https://openairdocs.org/files/sha256/f3/72/f37271389a7195f64650756a34a47d512a7aaa9b85f1d71e4f654ed6499943bd (from https://www.govinfo.gov/content/pkg/FR-2012-05-30/pdf/2012-13028.pdf)
- Federal Register: https://www.federalregister.gov/documents/2012/05/30/2012-13028/airworthiness-directives-the-boeing-company-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/12E9CB619A961F5386257A0E004A7C69.0001
- Page: https://openairdocs.org/proposed/FAA-2010-0856

## Summary

We are revising an earlier proposed airworthiness directive (AD) for certain the Boeing Company Model 737-600, -700, -700C, -800, and -900 series airplanes. That NPRM proposed to inspect for part numbers of the operational program software of the flight control computers, and corrective actions if necessary. That NPRM was prompted by reports of undetected erroneous output from a single radio altimeter channel, which resulted in premature autothrottle retard during approach. This action revises that NPRM by also proposing to supersede an existing AD. We are proposing this supplemental NPRM to detect and correct an unsafe condition associated with erroneous output from a radio altimeter channel, which could result in premature autothrottle landing flare retard and the loss of automatic speed control, and consequent loss of control of the airplane. Since the proposal to now supersede an existing AD may impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on this proposed change.

## Notices in this docket

- Sep 23, 2010: Notice of proposed rulemaking (NPRM). (first notice), FR document 2010-23857, comments due Nov 8, 2010 (https://www.federalregister.gov/documents/2010/09/23/2010-23857/airworthiness-directives-the-boeing-company-model-737-600--700--700c--800-and--900-series-airplanes)
- May 30, 2012: Supplemental notice of proposed rulemaking (NPRM); reopening of comment period., FR document 2012-13028, comments due Jul 16, 2012 (https://www.federalregister.gov/documents/2012/05/30/2012-13028/airworthiness-directives-the-boeing-company-airplanes)

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