# Airworthiness Directives; Agusta S.p.A. Helicopters
> **Rule** · Final rule. · Published 2012-06-25 · Effective 2012-07-30 · 77 FR 37779
## Document
- **Document number:** 2012-14797
- **Category:** airworthiness
- **Manufacturer:** Agusta S.p.A.
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 77 FR 37779
- **Publication date:** 2012-06-25
- **Effective date:** 2012-07-30
- **FAA docket:** Docket No. FAA-2012-0013
## Abstract

We are adopting a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model AB139 and AW139 helicopters with a certain generator control unit (GCU), to require replacing each affected GCU with an airworthy GCU. This AD was prompted by laboratory tests which revealed a potential fault in the overvoltage protection on a certain part-numbered GCU. The actions are intended to prevent failure of the overvoltage protection of the GCU, degraded performance of the electrical power generation and distribution systems, a fire, and subsequent loss of control of the helicopter.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2012/06/25/2012-14797/airworthiness-directives-agusta-spa-helicopters)
---
*AI Analytics · CC0 1.0*