AD/Bell 430/2 Power Turbine RPM Steady State Operation Avoidance (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 Canada (BHTC) 430 Series Helicopters

AD/BELL 430/2 Power Turbine RPM Steady
State Operation Avoidance 10/2005

Applicability:

Bell Helicopter Textron Canada (BHTC) Model 430 helicopters, serial numbers 49001 through 49111.

Requirement:

1.    Unless previously accomplished incorporate BHT-430-FM-1 Temporary Revision (TR15) or later Transport Canada approved revision into the rotorcraft flight manual.

2.    Unless previously accomplished, install the decal as per Alert Service Bulletin 430-05-34, dated 10 June 2005, or later Transport Canada approved revision.  It is permissible to locally manufacture the decal with white lettering on a black background, minimum 10 point font size.

Requirements 1 and 2 may be accomplished by a pilot endorsed on the Bell 430.

Note:  Transport Canada AD CF-2005-25 refers.

Compliance:

Within 10 calendar days after the effective date of this directive.

This Airworthiness Directive becomes effective on 29 September 2005.

Background:

Transport Canada has been advised of multiple reports of failure of the third stage turbine wheel used in both the Rolls-Royce 250-C30S and 250-C47B engines.  A similar turbine wheel is also installed in the 250-C40B engine which is utilized by BHTC for the Model 430.  Rolls-Royce has determined that detrimental vibrations can occur within a particular range of turbine speed as a potential contributing factor to these failures.  BHTC revised their rotorcraft flight manual and provided a decal to inform pilots to avoid steady-state operations at these engine turbine speeds.

James Coyne
Delegate of the Civil Aviation Safety Authority

15 August 2005