Bombardier (Boeing Canada/De Havilland)
Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes
Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes
| AD/DHC-8/149 | Spoiler Lift Dump Valve | 8/2009 |
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| Applicability: | Bombardier Inc. Models DHC-8-400, DHC-8-401 and DHC-8-402, Serial Numbers 4001 through 4237. |
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| Requirement: | Incorporate Bombardier Modsum 4 -113554 to add a Filter/Restrictor Fitting to the Spoiler Lift Dump Valve.Bombardier Service Bulletin 84-27-43, Initial Revision, dated 29 January 2009, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada provides approved instructions for incorporating Modsum 4 - 113554.Note: Transport Canada AD CF-2009-26 dated 21 May 2009 refers. |
| Compliance: | Within 5,000 flight hours after the effective date of this AD. |
| This Airworthiness Directive becomes effective on 30 July 2009. | |
| Background: | Several operators have reported cases of inadvertent single spoiler deployment during flight on the DHC-8 Series 400 aircraft. Investigation has revealed that the probable cause for this deployment is internal contamination of the Lift/Dump (L/D) valve and moisture ingress into the L/D valve armature. This condition, if not corrected, could cause uncommanded deployment of the spoilers resulting in increased drag and in combination with a loss of aileron, could result in a significant reduction in aircraft roll control. |
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James Coyne
Delegate of the Civil Aviation Safety Authority
19 June 2009