# Proposed AD 97-NM-157-AD: Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 97-09-15 R1
- Action: Notice of proposed rulemaking (NPRM).
- Published: November 13, 1997, 62 FR 60808
- Comments due: December 29, 1997
- Became: [AD 97-09-15 R1](https://openairdocs.org/ad/97-09-15-R1)
- Docket: 97-NM-157-AD
- FR document: 97-29820
- Official PDF: https://openairdocs.org/files/sha256/3a/d8/3ad883ecf2ef4e116340f1fe3dbd5a2624a6f8c916e741427d5ffb7d44d80730 (from https://www.govinfo.gov/content/pkg/FR-1997-11-13/pdf/97-29820.pdf)
- Federal Register: https://www.federalregister.gov/documents/1997/11/13/97-29820/airworthiness-directives-boeing-model-737-100--200--300--400-and--500-series-airplanes
- Page: https://openairdocs.org/proposed/97-NM-157-AD

## Summary

This document proposes to revise an existing airworthiness directive (AD), applicable to all Boeing Model 737-100, -200, -300, - 400, and -500 series airplanes, that currently requires a one-time inspection to determine the part number of the engage solenoid valve of the yaw damper on the rudder power control unit, and replacement of the valve with a valve having a different part number, if necessary. That AD was prompted by a review of the design of the flight control systems on Model 737 series airplanes. The actions specified by that AD are intended to prevent sudden uncommanded yawing of the airplane due to potential failures within the yaw damper system, and consequent injury to passengers and crewmembers. This action would make certain editorial changes to clarify the requirements of the existing AD.

## Notices in this docket

- Nov 13, 1997: Notice of proposed rulemaking (NPRM). (first notice), FR document 97-29820, comments due Dec 29, 1997 (https://www.federalregister.gov/documents/1997/11/13/97-29820/airworthiness-directives-boeing-model-737-100--200--300--400-and--500-series-airplanes)

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