AIRWORTHINESS DIRECTIVE
On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below repeals Airworthiness Directive (AD) AD/CL-600/111 and issues the following AD under subregulation 39.001 (1) of CASR 1998 and subsection 33 (3) of the Acts Interpretation Act 1901. 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-600/111 Amdt 1
Nose Landing Gear Selector Valve
9/2014
 
Applicability:
This AD applies to the following Bombardier Inc. aircraft:
Model CL-600-1A11 with Serial Numbers (S/N) from 1004 to 1085 inclusive;
Model CL-600-2A12 with S/N from 3001 to 3066 inclusive;
Model CL-600-2B16 with S/N from 5001 to 5194 inclusive;
Model CL-600-2B16 with S/N from 5301 to 5665 inclusive.

Requirement:
Check the nose landing gear (NLG) selector valve and NLG door selector valve that are installed on the aircraft and replace, rework, and identify the valves, as required, in accordance with the Accomplishment Instructions of the applicable Service Bulletin (SB) listed below, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.
Model
Service Bulletin
Date

CL-600-1A11 (CL-600)
SB 600-0721, Revision 03
23 February 2009

CL-600-2A12 (CL-601)
SB 601-0558, Revision 03
23 February 2009

CL-600-2B16 (CL-601-3A/3R)
SB 601-0558, Revision 03
23 February 2009

CL-600-2B16 (CL-604)
SB 604-32-021, Revision 04
23 February 2009

 
Accomplishment in accordance with 1 of the following SB revisions also satisfies the requirements of this AD:
- SB 600-0721 Revision 02, dated 16 June 2008;
- SB 601-0558, Revision 02, dated 16 June 2008;
- SB 604-32-021, Revision 03, dated 16 June 2008.

 
Accomplishment in accordance with the original issuance of, or an earlier revision of, the applicable SB does not satisfy the requirements of this AD.

 
Note 1:  The check is required whether or not an aircraft has previously been checked in accordance with AD/CL-600/86 (which was cancelled and superseded by
AD/CL-600/111). This is necessary since, following the issue of AD/CL-600/86, it has been determined that the S/N range of the affected valves requires expansion from the previous upper limit of S/N 0767 to S/N 2126 and the exact location of each of these additional valves is unknown.
Note 2:  Valves that have an S/N with suffix “T” have been manufactured by Tactair Fluid Controls Inc. and do not require any corrective action.
Note 3:  Valves manufactured by Kaiser Fluid Technologies, part number (P/N) 750006000, with S/N from 0001 to 2126 inclusive, and ink stamp “SB750006000-1”, have already been checked and reworked as necessary and do not require any additional corrective action.
Note 4:  A valve manufactured by Kaiser Fluid Technologies, with P/N 750006000, and S/N from 0001 to 2126 inclusive, must not be installed unless the marking “SB750006000-1” is ink stamped on the valve. The Illustrated Parts Catalogue for the relevant model gives this instruction.
Note 5:  CL-600-2B16 (CL-605) aircraft, with S/N of 5701 or higher, are not affected by this AD. They were delivered with valves, P/N 750006000, that either have an S/N with suffix “T” or have the ink stamp marking “SB750006000-1”.
Note 6:  Transport Canada AD CF-2009-21R1 dated 26 May 2009 refers. That AD superseded TC AD CF-2006-16R1, which was referred to in CASA AD/CL-600/86, and corrected an error in TC AD CF-2009-21 dated 6 May 2009.

Compliance:
The action set out in the requirement section must be taken by the earlier of the following:
(a)    within 250 flight hours after 30 July 2009;
(b)   the end of 30 January 2010.

 
This AD becomes effective on 9 May 2014.

Background:
A specific batch of NLG and NLG door selector valves, P/N 601R75146-1 (Kaiser Fluid Technologies P/N 750006000), may have had their end caps incorrectly lock‑wired or incorrectly torqued during assembly. This condition can lead to the end cap backing off, with consequent damage to a seal and internal leakage within the valve.
Subsequently, if electrical power is transferred or removed from the aircraft before the NLG safety pin is installed, any pressure, including residual pressure, in the No. 3 hydraulic system can result in an uncommanded NLG retraction.
Although there have been no such cases reported on the Challenger models covered by this AD, there have been 6 cases reported on the CRJ (CL600-2B19) aircraft, 1 of which resulted in the collapse of the NLG at the departure gate.

 
AD/CL-600/111 became effective on 30 July 2009. It mandated a check of the NLG and NLG door selector valves installed on all aircraft in the applicability section above. Depending on the results, replacement, rework and additional identification of the valves may be required.
This AD is issued to correct a typographical error in the table in the requirement section of AD/CL-600/111. The applicable service bulletin reference for the Model CL-600-2A12 (CL-601) has been corrected. There are no changes to the technical requirements or the compliance time of this AD from those in AD/CL-600/111.

Mike Higgins
Delegate of the Civil Aviation Safety Authority
29 April 2014