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 name. 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 may 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 by the Continuing Airworthiness Division (AARDG), National Aircraft Certification Branch, Transport Canada, Ottawa, telephone 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 Communications 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 

24-0022 (01-2005)

1/1 No.

CF-2011-05

Issue Date 

 24 March 2011 

Number: CF- 2011-05 

Subject: Horizontal Stabilizer Trim Actuator – Airworthiness Limitation Tasks 

Effective: 13 April 2011 

Applicability: All Bombardier Inc. Model BD-100-1A10 (Challenger 300) Aeroplanes 

Compliance: As indicated below unless already accomplished 

Background: It was discovered that the Horizontal Stabilizer Trim Actuator (HSTA) No Back and the 

Number 1 Motor Brake Assembly (MBA) can both 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 runaway without the ability to retrim. This 

condition, if not corrected, could lead to the loss of the aeroplane. 

As a result, new Airworthiness Limitation Tasks, consisting of a functional test of the 

HSTA No Back and a functional test of the HSTA Brake System, have been introduced to 

ensure that a dormant failure of either 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 incorporating 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 Temporary 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 exceeded 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.