AD/CL-600/67 Horizontal Stabilizer Trim Actuator (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-600/67 Horizontal Stabilizer Trim Actuator 10/2005

Applicability:

Bombardier Inc. Models:

CL-600-1A11 - Serial numbers 1004 through 1085
CL-600-2A12 - Serial numbers 3001 through 3066
CL-600-2B16 - Serial numbers 5001 through 5194

Requirement:

1.    Accomplish the following in accordance with the applicable Service Bulletin (SB) listed below, or later Transport Canada approved revisions.

a.     Immediately prior to proceeding with the Horizontal Stabiliser Trim Actuator (HSTA) modification in paragraph 1.c below, carry out a special check of the HSTA lower gimbal pin for migration by measuring the clearance between the yoke and the lower side of the gimbal pinhead.

b.    If gimbal pin migration is evident, replace the HSTA before further flight. Within seven (7) days of the inspection, notify Bombardier of the failure by completing and forwarding the Feedback form provided with the applicable SBs.

c.     If there is no evidence of gimbal pin migration, modify the HSTA by installing the gimbal pin kit (Bombardier P/N 600K0720; Goodrich P/N
52-210050) and re-identify the HSTA as per Goodrich VSB
21207-00X-27-05; or replace the installed HSTA with a HSTA that has previously been modified with the gimbal pin kit (Bombardier P/N 600K0720; Goodrich P/N 52-210050).

Applicable Service Bulletins.

CL-600-1A11 - SB 600-0720, dated 31 January 2005

CL-600-2A12 - SB 601-0555, dated 31 January 2005

CL-600-2B16 - SB 601-0555, dated 31 January 2005

2.    Replacement/spare HSTAs shall be modified with the gimbal pin kit (Bombardier P/N 600K0720; Goodrich P/N 52-210050) and re- identified as per Goodrich VSB 21207-00X-27-05.

Note:  Transport Canada AD CF-2005-20 refers.

Compliance:

1.   Within 600 hours time in service from the effective date of this directive but not later than 30 November 2006, whichever occurs first.

2.    From the effective date of this Directive, prior to being installed on any aircraft.

This Airworthiness Directive becomes effective on 29 September 2005.

Background:

Two failures have been reported of the lower gimbal primary pin of the HSTA.  In both failure cases, each found during routine maintenance, the primary pin had not migrated to the extent that the operation of the HSTA was impaired.  Analysis indicates that safety will be enhanced if additional pin retainer brackets are installed to mitigate lower gimbal pin migration.

James Coyne
Delegate of the Civil Aviation Safety Authority

15 August 2005