# Proposed AD 99-NM-67-AD: Boeing Model 747SP, 747SR, 747-100, 747-200, and 747-300 Series Airplanes; Equipped with Pratt & Whitney Model JT9D-3, -7, and -7Q Series Engines and Model JT9D-7R4G2 Engines

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2003-20-16
- Products: Boeing
- Product type: Aircraft
- Action: Supplemental notice of proposed rulemaking; reopening of comment period.
- Published: May 1, 2003, 68 FR 23235
- Comments due: May 27, 2003
- Became: [AD 2003-20-16](https://openairdocs.org/ad/2003-20-16)
- Docket: 99-NM-67-AD
- FR document: 03-10727
- Official PDF: https://openairdocs.org/files/sha256/80/fb/80fbd9c1856638764593336da31a7e3afca47d34d670fb31452d67a7014c26c9 (from https://www.govinfo.gov/content/pkg/FR-2003-05-01/pdf/03-10727.pdf)
- Federal Register: https://www.federalregister.gov/documents/2003/05/01/03-10727/airworthiness-directives-boeing-model-747sp-747sr-747-100-747-200-and-747-300-series-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/770123E5D0D3F19886256D19004C1863.0001
- Page: https://openairdocs.org/proposed/99-NM-67-AD

## Summary

This document revises an earlier proposed airworthiness directive (AD), applicable to certain Boeing Model 747SP, 747SR, 747-100, 747-200, and 747-300 series airplanes, that would have superseded an existing AD that currently requires repetitive operational tests of the reversible gearbox pneumatic drive unit (PDU) or the reversing air motor PDU to ensure that the unit can restrain the thrust reverser sleeve, and correction of any discrepancy found. The proposed AD also would have required installation of a terminating modification, and repetitive functional tests of that installation to detect discrepancies, and repair if necessary. This new action revises the proposed rule by removing airplanes from the applicability and adding new requirements. The actions specified by this new proposed AD are intended to ensure the integrity of the fail-safe features of the thrust reverser system by preventing possible failure modes in the thrust reverser control system that can result ininadvertent deployment of a thrust reverser during flight. This action is intended to address the identified unsafe condition.

## Notices in this docket

- Jan 26, 2000: Notice of proposed rulemaking (NPRM). (first notice), FR document 00-1778, comments due Mar 13, 2000 (https://www.federalregister.gov/documents/2000/01/26/00-1778/airworthiness-directives-boeing-model-747sp-sr--100--200-and--300-series-airplanes-equipped-with)
- May 1, 2003: Supplemental notice of proposed rulemaking; reopening of comment period., FR document 03-10727, comments due May 27, 2003 (https://www.federalregister.gov/documents/2003/05/01/03-10727/airworthiness-directives-boeing-model-747sp-747sr-747-100-747-200-and-747-300-series-airplanes)

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