AD/CL-600/109 Nose Landing Gear Selector Valve (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-600/109 Nose Landing Gear Selector Valve 7/2009

Applicability:

Bombardier Inc. Model CL-600-2B19, Serial Numbers (S/N) 7003 and subsequent.

Requirement:

1.    Check the S/N and identification markings on both the nose landing gear (NLG) selector valve and NLG door selector valve that are installed on the aircraft:

a.     If either or both selector valve S/Ns is in the range 0001 through 2126, and there is no suffix “T” or marking “SB750006000-1” on the valve, proceed to Requirement 2 of this AD.

b.    If both selector valves are identified with one or more of the following S/Ns or identification markings, no further action is required.  Compliance with this AD is complete:

- S/N outside the range 0001 through 2126;

- suffix "T";

- marking “SB750006000-1”.

2.    For each NLG selector valve and NLG door selector valve installed on the aircraft, that has a S/N in the range 0001 through 2126 but is not identified with suffix “T” or marking “SB750006000-1”:

Check the valve and replace, rework and/or identify the valve, as required, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 601R-32-104, dated 3 March 2009, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Note 1:  Valves that have a Serial Number (S/N) with suffix “T” has been manufactured by Tactair Fluid Controls Inc. and do not require any corrective action.

Note 2:  Valves manufactured by Kaiser Fluid Technologies, P/N 750006000, with S/N 0001 through 2126 and ink stamp “SB750006000-1”, have already been checked and reworked as necessary and do not require any additional corrective action.

Note 3.  The Illustrated Parts Catalogue (CSP A-006) gives instructions not to install a valve manufactured by Kaiser Fluid Technologies, P/N 750006000, with S/N 0001 through 2126, if marking “SB750006000-1” is not ink stamped on the valve.

Note 4:  Transport Canada AD CF-2009-19 dated 29 April 2009 refers.

Compliance:

Within 1600 flight hours or within 18 months after the effective date of this AD, whichever comes first.

This Airworthiness Directive becomes effective on 2 July 2009.

Background:

A specific batch of NLG and NLG door selector valves, part number (P/N) 601R75146-1 (Kaiser Fluid Technologies P/N 750006000), may have had their end caps incorrectly lock-wired and/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 and/or uncommanded opening of the NLG doors.  There have been six cases reported on CL600-2B19 aircraft, one of which resulted in the collapse of the NLG at the departure gate.

This AD mandates 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/or additional identification of the valves may be required.

James Coyne
Delegate of the Civil Aviation Safety Authority

22 May 2009