AD/DHC-8/137 Wing Front Spar to Fuselage Attachment (Cth)
AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes
| AD/DHC-8/137 | Wing Front Spar to Fuselage Attachment | 4/2008 DM |
Applicability: | DHC-8 aircraft, Models 400, 401, and 402, serial numbers 4001, and 4003 through 4176. |
Requirement: | Action in accordance with the requirements of Transport Canada Emergency AD Note: Bombardier Inc. Alert Service Bulletin A84-57-19 original issue, or later Transport Canada approved revision, refers. |
Compliance: | As specified in the Requirement document, with a revised effective date of 8 February 2008. |
| This Airworthiness Directive becomes effective on 8 February 2008. | |
Background: | During scheduled maintenance, an operator found cracks in the DSC228-16 barrel nut at one of the four primary front spar wing to fuselage attachment joints. The investigation determined that the cracks were due to hydrogen embrittlement and the problem is believed to be restricted to a batch of 166 barrel nuts from one supplier. Further inspection by a different operator revealed that cracked barrel nuts were found at three of the four wing front spar to fuselage joints on the same aircraft. All three barrel nuts were from the suspect batch. Failure of the barrel nuts could compromise the integrity of the wing to fuselage attachments. |
David Villiers
Delegate of the Civil Aviation Safety Authority
6 February 2008
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