# Airworthiness Directives; de Havilland Model DHC-8-100, -200, and -300 Series Airplanes
> **Rule** · Final rule. · Published 1997-09-29 · Effective 1997-11-03 · 62 FR 50861
## Document
- **Document number:** 97-25416
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 62 FR 50861
- **Publication date:** 1997-09-29
- **Effective date:** 1997-11-03
- **FAA docket:** Docket No. 97-NM-63-AD
## Abstract

This amendment adopts a new airworthiness directive (AD), applicable to certain de Havilland Model DHC-8-100, -200, and -300 series airplanes, that requires modification of the attitude and heading reference systems (AHRS). This amendment is prompted by a report of loss of power to both AHRS's during flight due to a faulty terminal block to which the signal ground for the AHRS's are connected. The actions specified by this AD are intended to prevent simultaneous power loss to both AHRS's, which could result in reduced controllability of the airplane.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1997/09/29/97-25416/airworthiness-directives-de-havilland-model-dhc-8-100--200-and--300-series-airplanes)
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