AD/GBK 117/8 Amdt 3 Tail Boom Vertical Fin Spar (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/GBK 117/8 Amdt 2 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.

Eurocopter BK 117 Series Helicopters

AD/GBK 117/8 Amdt 3 Tail Boom Vertical Fin Spar 3/2006

Applicability:

Models BK117A-1, A-3, A-4, B-1, B-2, and C-1 helicopters, all serial numbers.

Requirement:

1.    Incorporate Revision No. 35 (for MBB-BK117A-1 through B-2), and Revision No. 18 (for MBB-BK117C-1), into the MBB-BK117 Maintenance Manual.

2.    Inspect the vertical fin of the tail boom in accordance with the MBB-BK117 Maintenance Manual.

3.    If the inspection results are outside the allowable limits specified in the MBB-BK117 Maintenance Manual, ECD Customer Service must be consulted for advice on serviceability.

Note:  LBA AD D-1997-144R4 and Eurocopter Deutschland Alert Service Bulletin ASB-MBB-BK117-30-106 Revision 5 refer.

Compliance:

1.    Before 31 March 2006, unless already accomplished.

2.    As specified in the applicable MBB-BK117 Maintenance Manual.

3.    Before further flight.

This Amendment becomes effective on 16 March 2006.

Background:

This Directive was issued following a fatal accident overseas where the investigation revealed that the tail boom vertical fin had failed as a result of a fatigue crack that initiated on the left side of the vertical fin spar cap, and propagating across the cap and the web.

Amendment 1 provided relief with a repair/modification scheme, and an extended inspection period post repair/modification.

Amendment 2 introduced the latest revision of the Requirement document, which revised modification procedures.

Amendment 3 is issued in response to a revision of the related LBA AD, which now requires that all necessary inspection tasks be accomplished in accordance with the applicable MBB-BK117 Maintenance Manual.

The original issue of this Airworthiness Directive became effective on 9 May 1997.

David Villiers
Delegate of the Civil Aviation Safety Authority

3 February 2006