AD/Bell 427/3 Kaflex Drive Shaft (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (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 427 Series Helicopters

AD/BELL 427/3 Kaflex Drive Shaft 5/2006

Applicability:

Bell 427 helicopters.

Requirement:

Review the Historical Service Record of the KAflex shaft to determine if it was ever installed on a Bell Model 407 helicopter.

(a)   If the KAflex shaft has never been installed on a Bell Model 407 helicopter, then annotate the helicopter log book to show compliance with this AD and the following statement:

‘‘P/N 206-340-300-105 KAflex shaft has not been installed on a Bell 407”

(b)   If the KAflex shaft P/N 206-340-300-105 has been previously installed for any length of time on a Bell 407 helicopter, remove from service as per the applicable schedule published in BHTC Alert Service Bulletins 427-01-04, dated 12 October 2001, or later revisions approved by Transport Canada.

Note:  Transport Canada AD CF-2002-03R2 refers.

Compliance:

Within 30 days after the effective date of this AD, unless previously accomplished, thereafter at each time the shaft is replaced.

This Airworthiness Directive becomes effective on 11 May 2006.

Background:

During flight, the engine-to-transmission drive shaft assembly P/N 206-340-300-105 (KAflex shaft) failed, causing a forced landing.  Three additional incidents of a cracked flex frame on the forward end of the drive shaft on Model 407 have been reported.  As a precautionary measure, a one-time visual inspection for any obvious discrepancy of the shaft was mandated on Model 407 helicopters.

It has been determined that the KAflex shaft on Model 407 helicopters is experiencing higher loads than on other helicopter models.

Since the KAflex shaft P/N 206-340-300-105 can also be installed on Models 206L-4 and 427, this directive requires a component review to determine if this KAflex shaft was previously installed on Model 407.

James Coyne
Delegate of the Civil Aviation Safety Authority

17 March 2006