# .+. Transport Canada Transports

Canada TP 7245E 

# "No=·-----r-1c::-, CF.2009.29 111 Issue Dale 

### 29 June 

### 2009 

# AIRWORTHINESS DIRECTIVE
TM ,ollowingairuOf\hloe •• direeli"" (AD)may be appHoaoleto an a;r,,"a~ wnict1Ourrecord. IMlcaie is regisla",d in yoo, name. ADs are iOS"edpur"".n! lo CBfllJdjan A.I~tion Regufa~on

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6ranct1.Tran5PO'lCanada. on •••••••. lelep~ 613 ~-43S7 Number: Subject: Effective: Applicabilily: Compliance: Background:

Corrective Actions:

Authorization:

Contact: CF-2009-29

Nose Landing Gear
- Loss of Pivot Pin Retention Bolt 20 July 2009 Bombardier Inc. DHC-8 Aircraft, Models 400, 401 and 402, Serial Numbers 4001, 4003, 4004, 4006 and 4008 through 4238. As indicated below unless already accomplished. 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 boll 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 bon and a rework of the weight on wheel ryvOW) proximity sensor cover to provide clearance for the re-oriented retention bolt.
Within 2 000 hours air time after the effective date of this directive, incorporate Bombardier Modsum 4-113599. Bombardier Service Bulletin 84-32-65, initial Issue, dated 17 December 2008, or Revision A, dated 2 March 2009 or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada provides approved instructions for incorporating Modsum 4-113599.
For Minister of Transport, Infrastructure and Communities

Eric Lucas AlChief, Continuing Airworthiness Mr. Anthony Wan, Continuing Airworthiness, Ottawa, telephone 613-952-4410, facsimile 613-996-9178 or e-mail anthony.wan@tc.gc.caoranyTransportCanadaCentre.

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