# Proposed AD FAA-2008-0586: Bombardier Model DHC-8-400, -401 and - 402 Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2008-16-07
- Products: Bombardier
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: May 23, 2008, 73 FR 30005
- Comments due: June 23, 2008
- Became: [AD 2008-16-07](https://openairdocs.org/ad/2008-16-07)
- Docket: FAA-2008-0586 (https://www.regulations.gov/docket/FAA-2008-0586, where comments are filed)
- Project: 2008-NM-043-AD
- FR document: E8-11566
- Official PDF: https://openairdocs.org/files/sha256/cc/e7/cce7b9e16897ff27dfe11ec994f4221b7fdc903e6179b931c35761e3461bd4ad (from https://www.govinfo.gov/content/pkg/FR-2008-05-23/pdf/E8-11566.pdf)
- Federal Register: https://www.federalregister.gov/documents/2008/05/23/E8-11566/airworthiness-directives-bombardier-model-dhc-8-400--401-and--402-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/D6BFA1A9995B830386257452004A19CA.0001
- Page: https://openairdocs.org/proposed/FAA-2008-0586

## Summary

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

There was one reported failure of the elevator centering torsion spring. Investigation revealed that the tangs on the torsion spring had been bent due to difficulty encountered during installation of the elevator centering torsion spring on the horizontal stabilizer torque tube. The bending of the tangs on the torsion spring would degrade its durability and could lead to premature failure of the elevator centering torsion spring. A control rod disconnect between the elevator aft quadrant and the elevator Power Control Unit input torque tube, in combination with the loss or reduction in elevator centering capability, could result in a significant reduction in aircraft pitch control.

The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.

## Notices in this docket

- May 23, 2008: Notice of proposed rulemaking (NPRM). (first notice), FR document E8-11566, comments due Jun 23, 2008 (https://www.federalregister.gov/documents/2008/05/23/E8-11566/airworthiness-directives-bombardier-model-dhc-8-400--401-and--402-airplanes)

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