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 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 Can ada, 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 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

24-0022 (01-2005) 1/2 No

. CF-2010-23

Issue Date 21 July 2010

Number: CF- 2010-23

Subject: Main Landing Gear – Failure To Extend

Effective: 16 August 2010

Applicability: Bombardier Inc. DHC-8 Aeroplanes, Models 400, 401 and 402, Serial Numbers 4001 through 4247

Compliance: As indicated below unless already accomplished.

Background: One in-service incident has been reported on DHC-8 Series 400 aeroplane in which the right hand main landing gear (MLG) failed to extend using the alternate gear extension system. Investigation determined that the tread on the outboard tire was catching on the bumper plate located on the outboard MLG door that prevented the MLG door to open following an extension attempt via the alternate extension system. Failure of MLG to ex tend and lock could adversely affect the safe landing of the aeroplane.

To prevent the potential jam condition between the bumper plate and the MLG tires, Bombardier Aerospace has developed a modification to trim the edge of the bumper plate to eliminate the possibility of interference.

Corrective Actions: A. Within 2000 hours air time after the effective date of this directive, incorporate Bombardier Modsum 4-113645. A pproved instructions for incorporating Modsum 4-113645 are provided in Bombardier Service Bulletin (SB) 84-32-74, Revision A, dated 17 May 2010, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Note: Incorporation of Modsum 4-113645 in accordance with Bombardier SB 84-32-74, Initial Issue, dated 23 December 2009 requires complying with paragraph B.2 of this directive within 1000 hours air time after the effective date of this directive.

B. For aeroplanes that have the bumper plate, part number 85424082-101 and/or 85424082-103 reworked in accordance with Bombardier’s Repair Drawing (RD) 8/4-54-553, Issue 1 or later approved revisions, accomplish the following within 1000 hours air time after the effective date of this directive:No.
N ° CF-2010-23 2/2

1. Re-identify bump plate in accordance with Accomplishment Instructions, Paragraph 3.B, procedure step (8) of the above-mentioned SB or its later approved revisions.

2. Perform an operational check of the landing gear alternate extension system in accordance with Accomplishment Instructions, Paragraph 3.C, Close Out step (1) of the above-mentioned SB or its later approved revisions.

Authorization: For Minister of Transport, Infrastructure and Communities

ORIGINAL SIGNED BY

Robin Lau for Derek Ferguson Chief, Continuing Airworthiness

Contact: Mr. Anthony Wan, Continuing Airworthiness, Ottawa, telephone 613-952-4357, facsimile 613-996-9178 or e-mail CAWWEBFeedback@tc.gc.ca or any Transport Canada Centre.