Ad/DHC-8/151 - Spoiler Upload Valves and Rudder Shutoff Valves (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-8/151 Spoiler Upload Valves and
Rudder Shutoff Valves 10/2009

Applicability:

Bombardier Inc. Models DHC-8-400, DHC-8-401 and DHC-8-402, Serial Numbers (S/N) 4105 through 4179.

Requirement:

1.    Spoiler Unload Valve Manifold - Applicable to DHC-8 Aircraft, Models 400, 401, and 402, S/N 4105 through 4172:

Inspect the left hand and right hand spoiler unload valves Part Number (P/N) 396000-1005 for leaking or weeping in accordance with Bombardier Service Bulletin (SB) 84-27-37, dated 5 February 2009, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

a.     If leaking or weeping is found, replace the affected spoiler unload valve with a new valve.

b.    If no leaking or weeping is found, replace the inspected valve(s).

2.    Rudder Shutoff Valve Manifold - Applicable to DHC-8 Aircraft, Models 400, 401, and 402, S/N 4113 through 4179:

Inspect the left hand and right hand rudder shutoff valves P/N 412700-1001 for leaking or weeping in accordance with Bombardier SB 84-27-39, dated
5 February 2009, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

a.     If leaking or weeping is found, prior to further flight, replace the affected rudder shutoff valve with a new valve.

b.    If no leaking or weeping is found, replace the inspected valve(s).

3.    No replacement of Spoiler Unload Valves Assembly P/N 396000-1005, with serial numbers from 0289 through 0424 and Rudder Shutoff Valves P/N
412700-1001 with S/N from 0239 through 0384, are allowed to be installed on the DHC-8 Series 400 aeroplanes unless such valves have been inspected by the manufacturer and labelled with a suffix “A” after the S/N as indicated in the above-mentioned Service Bulletins.

Note:  Transport Canada AD CF-2009-25R1 dated 23 July 2009 refers.

Compliance:

For Requirement 1 - Within 750 flight hours after the effective date of this AD.

For Requirement 1.a. - Prior to further flight.

For Requirement 1.b. - Within 6,000 flight hours from the time of initial inspection mandated by this AD.

For Requirement 2 - Within 750 flight hours after the effective date of this AD.

For Requirement 2.a. - Prior to further flight.

For Requirement 2.b. - Within 6,000 flight hours from the time of initial inspection mandated by this AD.

For Requirement 3 - As of the effective date of this AD.

This Airworthiness Directive becomes effective on 24 September 2009.

Background:

During final Acceptance Test Procedure, a small oil leak was discovered on the Spoiler Unload Valve and Rudder Shutoff Valve bodies.  Investigation revealed that a number of valves were manufactured with an incorrect wall thickness.  This thin wall condition caused cracking, subsequent external weeping and pressure loss from the subject valves.

This condition, if not corrected, will cause a loss of hydraulic fluid and subsequent loss of spoiler and/or rudder control.

James Coyne
Delegate of the Civil Aviation Safety Authority

14 August 2009