# Proposed AD 96-SW-32-AD: Hiller Aircraft Corporation Model UH- 12A, UH-12B, UH-12C, UH-12D, and UH-12E Helicopters

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 97-20-15
- Action: Notice of proposed rulemaking (NPRM).
- Published: January 7, 1997, 62 FR 951
- Comments due: March 10, 1997
- Became: [AD 97-20-15](https://openairdocs.org/ad/97-20-15)
- Docket: 96-SW-32-AD
- FR document: 97-251
- Official PDF: https://openairdocs.org/files/sha256/4f/78/4f783a955857f27a9844edbbdeceb44f3b5260098c8656f7ee9aa384b1e27a81 (from https://www.govinfo.gov/content/pkg/FR-1997-01-07/pdf/97-251.pdf)
- Federal Register: https://www.federalregister.gov/documents/1997/01/07/97-251/airworthiness-directives-hiller-aircraft-corporation-model-uh--12a-uh-12b-uh-12c-uh-12d-and-uh-12e
- Page: https://openairdocs.org/proposed/96-SW-32-AD

## Summary

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to Hiller Aircraft Corporation (Hiller) Model UH-12A, UH-12B, UH-12C, UH-12D, and UH-12E helicopters, that currently requires a dye penetrant inspection of the head of the main rotor outboard tension-torsion (T-T) bar pin for cracks; a visual inspection of the outboard T-T bar pin for proper alignment and an adjustment, if necessary; and, installation of shims at the inboard end of the drag strut. This action would require the same actions required by the existing AD, but would allow a magnetic particle inspection of the T-T bar pin as an alternative to the currently required dye penetrant inspection, and would require reporting the results of the inspections only if cracks are found, rather than reporting all results of inspections as required by the existing AD. This proposal is prompted by an FAA analysis of a comment to the existing AD, and the fact that no cracks have been reported since the issuance of the existing AD. The actions specified by the proposed AD are intended to prevent cracks in the head area of the outboard T-T bar pin, which could result in loss of in-plane stability of the main rotor blade and subsequent loss of control of the helicopter.

## Notices in this docket

- Jan 7, 1997: Notice of proposed rulemaking (NPRM). (first notice), FR document 97-251, comments due Mar 10, 1997 (https://www.federalregister.gov/documents/1997/01/07/97-251/airworthiness-directives-hiller-aircraft-corporation-model-uh--12a-uh-12b-uh-12c-uh-12d-and-uh-12e)

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