# Proposed AD 97-SW-60-AD: Sikorsky Aircraft-Manufactured Model CH-54A Helicopters

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 99-07-16
- Action: Notice of proposed rulemaking (NPRM).
- Published: February 10, 1998, 63 FR 6685
- Comments due: April 13, 1998
- Became: [AD 99-07-16](https://openairdocs.org/ad/99-07-16)
- Docket: 97-SW-60-AD
- FR document: 98-3228
- Official PDF: https://openairdocs.org/files/sha256/b7/7e/b77ea1c752a8ceadabd2deb64e4c2220dd3e6e0d133a179c689480ec6e9b29a4 (from https://www.govinfo.gov/content/pkg/FR-1998-02-10/pdf/98-3228.pdf)
- Federal Register: https://www.federalregister.gov/documents/1998/02/10/98-3228/airworthiness-directives-sikorsky-aircraft-manufactured-model-ch-54a-helicopters
- Page: https://openairdocs.org/proposed/97-SW-60-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Sikorsky Aircraft-manufactured Model CH-54A helicopters. This proposal would require an initial and recurring inspections and rework or replacement, if necessary, of the second stage lower planetary plate (plate). This proposal is prompted by cracked plates that have been found during overhaul and inspections. The actions specified by the proposed AD are intended to prevent failure of the plate due to fatigue cracking, which could result in failure of the main gearbox, failure of the drive system, and subsequent loss of control of the helicopter.

## Notices in this docket

- Feb 10, 1998: Notice of proposed rulemaking (NPRM). (first notice), FR document 98-3228, comments due Apr 13, 1998 (https://www.federalregister.gov/documents/1998/02/10/98-3228/airworthiness-directives-sikorsky-aircraft-manufactured-model-ch-54a-helicopters)

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