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 39.1 (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.

Kawasaki BK 117 Series Helicopters

AD/JBK 117/22 Airwork Hoist Modification 11/2004

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Applicability: BK-117 helicopters with fitted with Airwork (NZ) Ltd hoist modification ARD/721, ARD/741, ARD/752, ARD/977, ARD/999.STC or STC.AW.0003.

Requirement: 1. Inspect the CABLE CUT switch guard in accordance with Airwork (NZ) Ltd Service Bulletin (SB) SB.AW.0001 Issue 1 dated 19 August 2004 to determine the part number (P/N) of the switch guard.

2.         If, as a result of the Requirement 1 inspection, the P/N of the switch guard is not MS25224-1, -2 or -3, replace the switch guard in accordance with SB.AW.0001 Issue 1.

3.         Replace the two position switch with a momentary action switch P/N MS24523- 26 or MS24524-26, as applicable, and if not already installed, fit switch guard P/N MS25224-3 in accordance with SB.AW.0001 Issue 1.

Note 1: Only switch guard P/N MS25224-3 is acceptable with the new momentary contact switch (P/N MS25224-1, -2 or -3 are acceptable prior to replacement of the switch).

Note 2: CAA(NZ) AD DCA/BK117/14 refers.

Compliance: For Requirement 1 - Before the next hoist operation after the effective date of this Directive.

For Requirement 2 - Before further operation of the hoist after the Requirement 1 inspection.

For Requirement 3 - Within 100 hours time in service after the effective date of this Directive.

This Airworthiness Directive becomes effective on 1 September 2004.

Kawasaki BK 117 Series Helicopters

AD/JBK 117/22 (continued)

Background: The Civil Aviation Authority of New Zealand has advised that an uncommanded activation of the pyrotechnic cable cutter has occurred on a helicopter fitted with Airwork hoist Modification ARD/741. Investigation of the incident identified two contributing factors.

The cable cut switch had developed a fault allowing the switch toggle to rest in the neutral position. The switch is a two position switch and when serviceable is spring loaded to either CLOSED or OPEN positions. Additionally, the cable cut switch guard was an incorrect part number. In combination, the unserviceable switch and the incorrect switch guard allowed the allowed the cable cut circuit to be activated when the guard was closed.

This Directive initially requires the correct switch guard to be installed, followed by a terminating action, which replaces the switch.

James Coyne

Delegate of the Civil Aviation Safety Authority 31 August 2004

The above AD is notified in the Commonwealth of Australia Gazette on 1 September 2004.