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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 ma y 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) 1/1 No

. CF-2010-17

Issue Date 02 June 2010

Number: CF- 2010-17

Subject: Tail Rotor Driveshaft Hanger Bearing Bracket - Cracking Due To Tooling Mark

Effective: 22 June 2010

Applicability: Bell Helicopter Textron Canada (BHTC), Model 427 helicopter, all serial numbers.

Compliance: As indicated unless already accomplished.

Background: Tail rotor driveshaft hanger bearing bra cket part number (P/N) 427-044-223-101 has been found cracked due to fatigue. It has been determined that the fatigue cracking was initiated by a tooling mark left during manufacture.

The existence of tooling marks on the bracke t could lead to bracket failure, loss of tail rotor drive and, consequently, loss of control of the helicopter.

Corrective

Actions: Part 1 Applicable to Model 427 helicopter, serial number 56001 through 56073, 56077,

58001 and 58002.

Within 30 days from the effective date of this directive, inspect and rework both sides of the hanger bracket P/N 427-044-223-101, in accordance with

A ccomplishment Instructions of Bell Helicopter Alert Service Bulletin (ASB) 427-09-29 Revision A dated 17 November 2009 or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada. Accomplishment of inspection and rework according to the original issue of ASB 427-09-29 fulfills the requirements of this paragraph.

Part 2 Applicable to Model 427 helicopter, all serial numbers.

As of the effective date of this direct ive, no operator may install replacement tail rotor driveshaft hanger bracket, P/N 427-044-223-101, unless the bracket has been inspected and reworked according to the original issue of Bell Helicopter ASB 427-09-29 or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada.

Authorization: For Minister of Transport, In frastructure and Communities



### ORIGINAL SIGNED BY

Derek Ferguson Chief, Continuing Airworthiness

Contact: Bogdan Gajewski, Continuing Airworthiness, Ottawa, telephone 613-952-4357, facsimile

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