Bombardier (Boeing Canada/De Havilland)
Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes
Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes
| AD/DHC-8/117 | Rudder Trim Switch Wiring | 4/2006 |
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| Applicability: | DHC-8 Models 401 and 402, serial numbers 4005, 4006, 4008 through 4016 and 4018 through 4058. |
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| Requirement: | 1. If not previously accomplished, carry out the following in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin (ASB)A84-27-13 Revision B, dated 12 January 2002, or later revisions, approved by the Chief, Continuing Airworthiness, Transport Canada: |
| a. Modify the wiring for the rudder trim switch (2722-S2) by incorporating Modsum 4-126256; and | |
| b. Visually inspect all wiring on the back of the aileron/rudder trim control panel (P/N 82410608-001, -003 or -005) for chafing. | |
| Note 1: Aircraft modified and inspected in accordance with the Accomplishment Instructions of ASB A84-27-13 Revision A, dated 9 January 2002, also satisfy the requirements of this Directive. | |
| 2. Replace any chafed wiring found during the Requirement 1.b. inspection. | |
| Note 2: Transport Canada AD CF-2002-15 refers. | |
| Compliance: | For Requirement 1 - Within 30 days after the effective date of this Directive. |
| For Requirement 2 - Before further flight after the Requirement 1.b. inspection. | |
| This Airworthiness Directive becomes effective on 13 April 2006. |
| Background: | Transport Canada has advised that an investigation of an incident involving rudder trim runaway has revealed a discrepancy in the wiring of the rudder trim control switch on the aileron/rudder trim control panel. The wiring discrepancy in the rudder trim switch could potentially enable a single short circuit on the aileron/rudder trim control panel to cause a runaway condition of the rudder trim actuator |
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James Coyne
Delegate of the Civil Aviation Safety Authority
2 March 2006