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. Agusta A109 Series Helicopters AD/A109/56 Exhaust Duct Clamps 4/2007 Applicability: Agusta A109A, A109AII and A109C helicopters. Requirement: 1. Inspect the exhaust duct grooved clamps Part Number (P/N) 4606AC in accordance with Agusta "Bollettino Tecnico" 109-123 original issue or later approved revision. 2. If cracks and/or corrosion are found replace the affected clamp. Note: EASA AD 2007-0041 dated 21 February 2007 refers. Compliance: 1. Within 50 flight hours after the effective date of this AD and not later than 12 May 2007, thereafter at intervals not to exceed 300 flight hours or yearly whichever occurs first. 2. Before further flight after the effective date of this AD. This Airworthiness Directive becomes effective on 12 April 2007. Background: A failure of the grooved clamp led to the loss of the exhaust duct. The duct subsequently stuck and caused failure of the tail rotor. This led to an emergency landing of the helicopter. This AD requires a repeated visual inspection of the exhaust duct clamps for cracking and corrosion to prevent such a failure re-occurring. David Punshon Delegate of the Civil Aviation Safety Authority 28 February 2007