# Proposed AD 94-SW-29-AD: Bell Helicopter Textron, Inc. Model 214B, 214B-1, and 214ST Helicopters

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 98-18-01
- Action: Notice of proposed rulemaking (NPRM).
- Published: December 12, 1996, 61 FR 65367
- Comments due: February 10, 1997
- Became: [AD 98-18-01](https://openairdocs.org/ad/98-18-01)
- Docket: 94-SW-29-AD
- FR document: 96-31523
- Official PDF: https://openairdocs.org/files/sha256/05/30/053058bfff204dc86274d91e4cc28cbbeae08717cf8d664e2c42e5fb7c9e2072 (from https://www.govinfo.gov/content/pkg/FR-1996-12-12/pdf/96-31523.pdf)
- Federal Register: https://www.federalregister.gov/documents/1996/12/12/96-31523/airworthiness-directives-bell-helicopter-textron-inc-model-214b-214b-1-and-214st-helicopters
- Page: https://openairdocs.org/proposed/94-SW-29-AD

## Summary

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to Bell Helicopter Textron, Inc. (BHTI) Model 214B, 214B-1, and 214ST helicopters, that currently establishes a retirement life of 60,000 high-power events for the main rotor trunnion (trunnion). This proposal would require changing the method of calculating retirement life for the trunnion from high power events to a maximum accumulated Retirement Index Number (RIN). This proposal is prompted by fatigue analyses and tests that show certain trunnions fail sooner than originally anticipated because of the unanticipated higher number of lifts or takeoffs (torque events) performed with those trunnions in addition to the time-in-service (TIS) accrued under other operating conditions. The actions specified by the proposed AD are intended to prevent fatigue failure of the trunnion, which could result in loss of the main rotor and subsequent loss of control of the helicopter.

## Notices in this docket

- Dec 12, 1996: Notice of proposed rulemaking (NPRM). (first notice), FR document 96-31523, comments due Feb 10, 1997 (https://www.federalregister.gov/documents/1996/12/12/96-31523/airworthiness-directives-bell-helicopter-textron-inc-model-214b-214b-1-and-214st-helicopters)

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