# Airworthiness Directives; Bombardier Model DHC-8 Series Airplanes
> **Rule** · Final rule. · Published 1999-08-20 · Effective 1999-09-24 · 64 FR 45425
## Document
- **Document number:** 99-21362
- **Category:** airworthiness
- **Manufacturer:** Bombardier Model DHC-8 Series
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 64 FR 45425
- **Publication date:** 1999-08-20
- **Effective date:** 1999-09-24
- **FAA docket:** Docket No. 99-NM-55-AD
## Abstract

This amendment adopts a new airworthiness directive (AD), applicable to certain Bombardier Model DHC-8 series airplanes, that requires a one-time inspection of the spring assemblies located in the rudder control feel unit to verify that dual rate configuration springs are installed; and revising the Airplane Flight Manual to prohibit airplane operation from runways less than 75 feet wide, if necessary. This amendment also requires eventual replacement of any single rate configuration springs with dual rate configuration springs, which terminates the requirement for the AFM revision. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent an asymmetric rudder force condition, which could result in reduced controllability of the airplane and consequent potential for center line deviation.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1999/08/20/99-21362/airworthiness-directives-bombardier-model-dhc-8-series-airplanes)
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