Transport Transports Canada Canada TP 7245E



# AIRWORTHINESS DIRECTIVE

The following airworthiness directive (AD) may be applicable to an aircraft which our records indicate is registered in your na me. ADs are issued pursuant to Canadian Aviation Regulation (CAR) 521 Division X . Pursuant to CAR 605.84 and the further details of CAR Standard 625, Appendix H , the continuing airworthiness of a Canadian registered aircraft is contingent upon compliance with all applicable ADs. Failure to comply with the requirements of an AD ma y invalidate the flight authorization of the aircraft. Alternative means of compliance shall be applied for in accordance with CAR 605.84 and the above-referenced Standard

. This AD has been issued b y the Continuin g Airworthiness Division ( AARDG ) , National Aircraft Certification Branch, Trans p ort Canada, Ottawa, tele p hone 613 952-4357.

Pursuant to CAR 202.51 the registered owner of a Canadian aircraft shall, within seven days, notify the Minister in writing of any change of his or her name or address. To request a change of address, contact the Civil Aviation Communicat ions Centre (AARC) at Place de Ville, Ottawa, Ontario K1A 0N8 , or 1-800-305-2059 , or www.tc.gc.ca/civilaviation/communications/centre/ address.asp

2 4-0022 ( 01-2005 ) 1/1 No

. CF-2011-05 Issue Date 24 March 2011

Number: CF- 2011-05 Subject: Horizontal Stabilizer Trim Ac tuator – Airworthiness Limitation Tasks Effective: 13 April 2011 Applicability: All Bombardier Inc. M odel BD-100-1A10 (Challenger 300) Aeroplanes Compliance: As indicated below unless already accomplished Background: It was discovered that the Horizontal Stabiliz er Trim Actuator (HSTA) No Back and the Number 1 Motor Brake Assembly (MBA) can bot h fail dormant. A failure of the HSTA No Back and the Brake System along with additional component failure could result in an uncontrollable horizontal stabilizer surface r unaway without the ability to retrim. This condition, if not corrected, could lead to the loss of the aeroplane. As a result, new Airworthiness Limitation Ta sks, consisting of a functional test of the HSTA No Back and a functional test of t he HSTA Brake System, have been introduced to ensure that a dormant failure of eit her component is detected and corrected.

This directive mandates the revision of the approved maintenance schedule to include these new tasks, including phase-in schedules. Corrective Actions: Within 30 days after the effective date of this directive, revise the Transport Canada approved maintenance schedule by inco rporating Task Numbers 27-40-00-107 (Functional Test of the HSTA No Back) and 27-41-05-105 (Functional Test of the HSTA Brake System), as introduced by the Tempor ary Revision (TR) 5-2-59 of Challenger 300 (Model BD-100-1A10) Time Limits/Maintenance Checks (TLMC) Manual, CH 300 TLMC. The above referenced tasks contain phase-in schedules, as necessary, for aeroplanes with actuators that have exc eeded the initial task interval. Compliance with superseding TR or later revisions of the above TLMC Manuals approved by Transport Canada, also satisfies the requirements of this directive. Authorization: For the Minister of Transport, Infrastructure and Communities

ORIGINAL SIGNED BY

Derek Ferguson Chief, Continuing Airworthiness Contact: Miss Helen Tsai, Continuing Airworthiness, Ottawa, telephone 613-952-4357, facsimile 613-996-9178 or e-mail CAWWEBFeedback@tc.gc.ca or any Transport Canada Centre.