AD/Bell 407/28 Amdt 1 Freewheel Aft Bearing Cap (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/BELL 407/28 and issues the following AD under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Bell Helicopter Textron Canada (BHTC) 407 Series Helicopters

AD/BELL 407/28 Amdt 1 Freewheel Aft Bearing Cap 7/2005

Applicability:

Bell Helicopter Textron Canada (BHTC) model 407 helicopters fitted with freewheel aft bearing cap P/N 406-040-509-101, serial numbers A-1833 through A-1912.

Requirement:

1.     Identify the aft bearing cap serial numbers for applicability in accordance with Part I of BHTC Alert Service Bulletin (ASB) 407-04-66 Revision A dated 01 December 2004 or later revision approved by Transport Canada.

2.     Depending on the average engine start cycle count, rework the affected freewheel aft bearing caps in accordance with Part II or Part III of the ASB.

3.     Rework the freewheel assembly in accordance with Part IV of the ASB.

Note:  Transport Canada AD CF-2004-17 R1 dated 11 February 2005 refers.

Compliance:

1.     Within 7 days after the effective date of this Directive.

2.     Unless previously accomplished, within 50 flight hours after the effective date of this directive.

3.     Unless previously accomplished, within 300 flight hours after the effective date of this directive, but no later than 30 September 2005.

This Amendment becomes effective on 7 July 2005.

Background:

Due to an oversight during manufacturing, a lubrication channel to allow oil flow has not been machined into an identifiable batch of aft bearing caps.  Omission of lubrication channel may cause lack of lubrication and reduced durability.  As a result, freewheel unit may cease to function.

Amendment 1 is issued in response to a revision of the related Transport Canada AD which places an ultimate life on affected freewheel assembly components that have operated with a defective aft bearing cap.

The original issue of this Airworthiness Directive became effective on 23 December 2004.

James Coyne
Delegate of the Civil Aviation Safety Authority

27 May 2005