# Proposed AD 99-NM-55-AD: Bombardier Model DHC-8 Series Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 99-17-14
- Action: Notice of proposed rulemaking (NPRM).
- Published: June 22, 1999, 64 FR 33232
- Comments due: July 22, 1999
- Became: [AD 99-17-14](https://openairdocs.org/ad/99-17-14)
- Docket: 99-NM-55-AD
- FR document: 99-15773
- Official PDF: https://openairdocs.org/files/sha256/84/59/8459b87fabbffa3bb5d68269af05afdba50d6dc0860a9e7035e27336b851f8b9 (from https://www.govinfo.gov/content/pkg/FR-1999-06-22/pdf/99-15773.pdf)
- Federal Register: https://www.federalregister.gov/documents/1999/06/22/99-15773/airworthiness-directives-bombardier-model-dhc-8-series-airplanes
- Page: https://openairdocs.org/proposed/99-NM-55-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Bombardier Model DHC-8 series airplanes. This proposal would require 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 proposal also would require eventual replacement of any single rate configuration springs with dual rate configuration springs, which would terminate the requirement for the AFM revision. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed 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.

## Notices in this docket

- Jun 22, 1999: Notice of proposed rulemaking (NPRM). (first notice), FR document 99-15773, comments due Jul 22, 1999 (https://www.federalregister.gov/documents/1999/06/22/99-15773/airworthiness-directives-bombardier-model-dhc-8-series-airplanes)

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.