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) 593. 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-2009-29R1

Issue Date 

 14 August 2013 

Number: CF-2009-29R1 

Subject: Nose Landing Gear – Loss of Pivot Pin Retention Bolt 

Effective: 28 August 2013 

Revision: Supersedes Airworthiness Directive CF-2009-29, issued on 29 June 2009. 

Applicability: Bombardier Inc. model DHC-8-400, -401 and -402 aeroplanes, serial numbers 4001

through 4435 

Compliance: As indicated below, unless already accomplished. 

Background: Two in-service incidents have been reported on DHC-8 Series 400 aircraft in which the 

nose landing gear (NLG) trailing arm pivot pin retention bolt (part number NAS6204-13D) 

was damaged. One incident involved the left hand NLG tire which ruptured on take-off. 

Investigation determined that the retention bolt failure was due to repeated contact of the 

castellated nut with the towing device including both the towbar and the towbarless rigs. 

The loss of the retention bolt allowed the pivot pin to migrate from its normal position and 

resulted in contact with and rupture of the tire. The loss of the pivot pin could compromise 

retention of the trailing arm and could result in a loss of directional control due to loss of 

nose wheel steering. The loss of an NLG tire or the loss of directional control could 

adversely affect the aircraft during take off or landing. 

To prevent the potential failure of the pivot pin retention bolt, Bombardier Aerospace has 

developed a modification which includes a new retention bolt, a reverse orientation of the 

retention bolt and a rework of the weight on wheel (WOW) proximity sensor cover to provide 

clearance for the re-oriented retention bolt. 

Since the original issue of this AD, there have been several reports of pivot pin retention 

bolts found missing or damaged. Additional investigation determined that the failures were 

caused by high contact stresses on the retention bolt due to excessive frictional torque on 

the pivot pin and an adverse tolerance condition at the retention bolt. 

Revision 1 of this AD mandates the installation of a new pivot pin retention mechanism. 

Corrective 

Actions:

Within 6000 hours air time or 36 months, whichever occurs first, from the effective date of 

this AD, incorporate Bombardier Modsum 4-113749. Bombardier Service Bulletin 84-32-

110, Revision A, dated 8 April 2013, or later revisions approved by the Chief, Continuing 

Airworthiness, Transport Canada, provides approved instructions for incorporating 

Modsum 4-113749. 

Incorporation of Modsum 4-113749 in accordance with Bombardier SB 84-32-110, Initial 

Issue, dated 21 December 2012, prior to the effective date of this AD, also satisfies the 

requirements of this AD. 

Authorization: For the Minister of Transport, 

ORIGINAL SIGNED BY 

Philip Tang 

Acting Chief, Continuing Airworthiness 

Contact: Robert Farinas, Continuing Airworthiness, Ottawa, telephone 613-952-4357, facsimile 

613-996-9178 or e-mail AD-CN@tc.gc.ca or any Transport Canada Centre.