# Airworthiness Directives; Enstrom Helicopter Corporation Helicopters
> **Rule** · Final rule; request for comments. · Published 2012-06-18 · Effective 2012-07-03 · 77 FR 36131
## Document
- **Document number:** 2012-14634
- **Category:** airworthiness
- **Manufacturer:** Enstrom Helicopter Corporation
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 77 FR 36131
- **Publication date:** 2012-06-18
- **Effective date:** 2012-07-03
- **FAA docket:** Docket No. FAA-2012-0562
## Abstract

We are superseding an existing airworthiness directive (AD) for Enstrom Helicopter Corporation (Enstrom) Model F-28C, F-28C-2, F- 28F, 280C, 280F, 280FX, TH-28, 480, and 480B helicopters to add another trim relay to the applicability and to revise the modification instructions. This AD is prompted by the discovery that another part- numbered trim relay, inadvertently omitted from the current AD, may contain the same unsafe condition. These actions are intended to prevent failure of the cyclic trim system and subsequent loss of control of the helicopter.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2012/06/18/2012-14634/airworthiness-directives-enstrom-helicopter-corporation-helicopters)
---
*AI Analytics · CC0 1.0*