# Proposed AD 99-NM-21-AD: Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2002-05-07
- Products: Boeing
- Product type: Aircraft
- Action: Supplemental notice of proposed rulemaking; reopening of comment period.
- Published: August 2, 2001, 66 FR 40162
- Comments due: September 6, 2001
- Became: [AD 2002-05-07](https://openairdocs.org/ad/2002-05-07)
- Docket: 99-NM-21-AD
- FR document: 01-19261
- Official PDF: https://openairdocs.org/files/sha256/92/2e/922e60fb8078fb9c9f209fcd58abc17c6d4a8e5231b69196bc11a5a1033fcf17 (from https://www.govinfo.gov/content/pkg/FR-2001-08-02/pdf/01-19261.pdf)
- Federal Register: https://www.federalregister.gov/documents/2001/08/02/01-19261/airworthiness-directives-boeing-model-737-100--200--200c--300--400-and--500-series-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/7606C00D1A61296B86256A9C006BDAB2.0001
- Page: https://openairdocs.org/proposed/99-NM-21-AD

## Summary

This document revises an earlier proposed airworthiness directive (AD); applicable to certain Boeing Model 737-100, -200, and -200C series airplanes; which would have required inspections for corrosion and cracking of the inboard track of each outboard flap, and repair, if necessary, and would have provided an optional terminating action. This new action expands the applicability and removes the optional terminating action of the proposed AD. For certain airplanes, this action would require new repetitive inspections for discrepancies of the rear spar attachments and cracks in the upper flange of the inboard track at the rear spar attachment of each outboard flap, and eventual rework of the flap track assembly and rear spar attachments, including replacement of the flap track with a new track, if necessary. For all airplanes, this action would require repetitive inspections for cracks in the upper flange of the inboard flap tracks at the rear spar attachments, and corrective action, if necessary. These actions are necessary to find and fix discrepancies of the inboard tracks of the outboard flaps, which could result in loss of the outboard trailing edge flaps and consequent reduced controllability of the airplane. These actions are intended to address the identified unsafe condition.

## Notices in this docket

- Apr 26, 1999: Notice of proposed rulemaking (NPRM). (first notice), FR document 99-10347, comments due Jun 10, 1999 (https://www.federalregister.gov/documents/1999/04/26/99-10347/airworthiness-directives-boeing-model-737-100--200-and--200c-series-airplanes)
- Aug 2, 2001: Supplemental notice of proposed rulemaking; reopening of comment period., FR document 01-19261, comments due Sep 6, 2001 (https://www.federalregister.gov/documents/2001/08/02/01-19261/airworthiness-directives-boeing-model-737-100--200--200c--300--400-and--500-series-airplanes)

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