AD/CL-600/79 Aileron Power Control Unit Links (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 (Canadair) CL-600 (Challenger) Series Aeroplanes

AD/CL-600/79 Aileron Power Control Unit Links 9/2007

Applicability:

Bombardier Inc. Model CL-600-2B19 - CRJ-100/440 - serial numbers 7003 and subsequent.

Requirement:

Accomplish the following in accordance with Bombardier Alert Service Bulletin (ASB) A601R-27-130, Revision A dated 22 December 2003, or later NAA approved revisions:

1.    Conduct a detailed visual inspection of the four aileron PCU links for fractures/cracks and replace any fractured/cracked link prior to further flight.

2.    As part of the replacement of fractured/cracked links, perform the following:

a.     Record the torque value of the forward and aft attachment bolts for both PCU links for the applicable aileron; and

b.    Check for mismatch between PCU link and the PCU output fork; and

c.     Perform an eddy current inspection of the aileron PCU lugs, and if a crack is found, contact Bombardier in accordance with the above-mentioned ASB; and

d.    Record the information requested in Appendix A and Appendix B of the above-mentioned Bombardier ASBs.

3.    Aircraft that had the initial aileron PCU link inspection, and if necessary replacement, performed in accordance with ASB A601R-27-130, dated
13 November 2003, meet the requirements of Requirement 1 and 2a, b and d of this AD.  However, aircraft that were found with a fractured/cracked aileron PCU link and were not subject to an NDT inspection of the aileron lugs, are to have an NDT inspection of the applicable aileron lugs, required under Requirement 2c of this AD carried out.

4.    Forward the information requested in Appendix A and B of the above mentioned ASBs, or later NAA approved revision, and any associated fractured/cracked link(s), to Bombardier Aerospace at the address provided in the Bombardier ASBs.

5.    Repeat the inspection and checks of the aileron PCU links detailed in Requirement 1 and 2 of this AD.

Note:  Transport Canada AD CF-2004-13 dated 20 July 2004 refers.

Compliance:

For Requirements 1 and 2:

Unless previously accomplished, aircraft that have accumulated 2,000 flight hours or more upon the effective date of this AD; prior to accumulating 550 flight hours from the effective date of this AD; and

Aircraft with less than 2,000 flight hours upon the effective date of this directive; prior to reaching 2,000 flight hours or prior to accumulating 550 flight hours from the effective date of this directive, whichever is reached later.

For Requirement 3:

At the next repeat visual inspection of the aileron PCU link as detailed in Requirement 5 of this AD.

For Requirement 4:

Within 30 days of the initial inspection, unless previously accomplished.

For Requirement 5:

At intervals not to exceed 1000 flight hours.

This Airworthiness Directive becomes effective on 30 August 2007.

Background:

Transport Canada has received reports of aileron power control unit (PCU) link failures on several in-service aircraft.  Failure of one link is considered to be a dormant failure; failure of both PCU links to an aileron could result in reduced lateral control of the aircraft.

David Punshon
Delegate of the Civil Aviation Safety Authority

25 June 2007