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)

1/2 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 extend 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. Approved 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.