AD/CL-600/10 - Autopilot Duplex Servo - Installation of Protective Cover

This Airworthiness Directive mandates a safety modification for Bombardier Challenger CL-600 aircraft.

What it requires: Operators must install a protective cover on the autopilot duplex servo system, following the technical instructions in Canadair Service Bulletin No. 600-0171.

Who it affects: All CL-600 series aircraft listed in the referenced service bulletin.

When it must be done: Before the aircraft can be issued with an Australian Certificate of Airworthiness (meaning the modification is a prerequisite for legal operation).

Why it matters: The cover prevents foreign objects—such as debris, tools, or other items—from jamming the servo capstan (a rotating pulley that helps control the aircraft's movements). A jammed autopilot servo could cause sudden, unexpected aircraft movements or loss of control, creating serious safety risks during flight.

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COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source Bombardier (Canadair) CL-600 (Challenger) Series Aeroplanes

AD/CL-600/10 Autopilot Duplex Servo - Installation

of Protective Cover Applicability: All CL600 aeroplanes listed in the requirement document. Document: Canadair Challenger SB No. 600-0171.

Compliance: Before issue of Australian Certificate of Airworthiness.

Background: To prevent foreign objects from jamming the autopilot servo capstan.

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