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) 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 invalidat e 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 Communica tions Centre (AARC) at Place de Ville, Ottawa, Ontario K1A 0N8 , or 1-800-305-2059
, or www.tc.gc.ca/civilaviation/communications/centre/ addr ess.asp

2 4-0022 ( 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 Direct ive 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 pi n retention bolt (part number NAS6204-13D) was damaged. One incident involved the left hand NLG tire which ruptured on take-off. Investigation determined that t he retention bolt failure was due to repeated contact of the castellated nut with the towing device incl uding both the towbar and the towbarless rigs. The loss of the retention bolt allowed the pivo t 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 re tention bolt, a reverse orientation of the retention bolt and a rework of the weight on w heel (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 invest igation determined that the failures were caused by high contact stresses on the retent ion 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 accor dance with Bombardier SB 84-32-110, Initial Issue, dated 21 December 2012, prior to the effe ctive 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.