Document ID: chunk:federal_register_of_legislation:F2006L03505:body:0:p2
Version: federal_register_of_legislation:F2006L03505
Segment Type: other
Provision Reference: 
Character Range: 2878–4400

Requirements 1 2 and 3 - Within 14 days after the effective date of this Amendment.
             For Requirement 4 - Within 12 months of the effective date of this Amendment.
             This Amendment becomes effective on 27 October 2006.
Background:  Transport Canada has received reports of uncommanded horizontal stabilizer trim motion on two CL-600-2B16 (CL-604) aircraft.  In each case, the aircraft landed safely.
             An investigation has revealed that a motherboard in the horizontal stabiliser trim control unit (HSTCU) had not had appropriate environmental protection applied during manufacture.  The absence of corrosion protection and the accumulation of moisture during flight, caused short circuits that resulted in autopilot disconnect and trim system malfunctions.  The trim problems included uncommanded trim, trim in a direction opposite to that selected, loss of trim position indication and, in one case, potential loss of trim disconnect capability.
             This Amendment enhances the AFM stabilizer trim runaway procedure, mandates the installation of circuit breaker (CB) quick identification collars for the HSTCU CBs, and introduces some additional trim system pre-flight checks for the flight crew.  The installation of a modified HSTCU with environment protection on the motherboard provides terminating action.
             The original issue of this Directive became effective on 6 September 2006.

James Coyne
Delegate of the Civil Aviation Safety Authority

23 October 2006