AD/Bell 430/12 Disc Assemblies Tail Rotor Driveshaft (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 430/12 Disc Assemblies - Tail Rotor Driveshaft 12/2007 DM

Applicability:

Bell Helicopter Textron Canada (BHTC) Model 430 helicopters S/N up to 49120 fitted with disc assemblies part number (P/N) 36300-1, 37855-1 and C048354-1.

Requirement:

1.    Verify disc assemblies P/N 36300-1, 37855-1 and C048354-1 for manufacturing date, proper thickness and indexing, in accordance with the instructions provided in BHTC Alert Service Bulletin (ASB) ASB-430-07-40 dated 28 March 2007 or later approved revisions.

       If disc assemblies, after verification in accordance with Requirement 1, do not require any further action, or if the manufacturing date is not between 01 November 2005 and 30 November 2006, make an appropriate log book entry to this effect. No further action is required.

2.    Remove any disc assembly which is not within the required thickness as per table below:

Disc Assembly P/N	Total Thickness
Minimum	Maximum
36300-1	0.174 inch (4.42 mm)	0.186 inch (4.75 mm)
37855-1	0.126 inch (3.20 mm)	0.138 inch (3.50 mm)
C048354-1	0.046 inch (1.16 mm)	0.051 inch (1.29 mm)

3.    Remove any disc assembly which is not properly indexed.

4.    Do not install any of the disc assemblies P/N 36300-1, 37855-1 and C048354-1 into any helicopter unless it is compliant to the ASB-430-07-40 dated 28 March 2007 or later approved revisions.

Note:  Transport Canada Airworthiness Directive CF-2007-15 dated 24 August 2007 refers.

Compliance:

1.    Unless already accomplished, no later than 25 flight hours or 30 days from the effective date of this directive, whichever comes first.

2.    Within 10 flight hours, after the completion of requirement 1.

3.    Within 300 flight hours or at next scheduled inspection, whichever comes first, after the completion of requirement 1.

4.    After the effective date of this Airworthiness Directive.

This Airworthiness Directive becomes effective on 3 October 2007.

Background:

Transport Canada has determined that disc assemblies part number (P/N) 36300-1, 37855-1 and C048354-1 manufactured between 1 November 2005 and 30 November 2006, may have discs of improper thickness or discs may have been indexed incorrectly.

David Villiers
Delegate of the Civil Aviation Safety Authority

28 September 2007