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/BELL 47/71 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. Bell Helicopter Textron 47 (All Variants) Series Helicopters AD/BELL 47/71 Amdt 1 Tail Rotor Blades 10/2005 Applicability: All model 47 with tail rotor blades P/N 47-642-117. Requirement: Carry out the requirement of Bell Technical Bulletin No. 47-05-73-1. This Directive shall be entered on the Maintenance Release as maintenance required. In addition to a Maintenance Engineer qualified on the type, the required inspection may be performed and certified by a Pilot in Command who has been trained to do the inspection by an appropriately qualified person. In this case, a copy of this Directive is to be carried in the aircraft. Compliance: At each daily or overnight inspection. This Amendment becomes effective on 29 September 2005. Background: This AD was raised after several reports of cracking in the skin of the tail rotor blades. The cracks were located approximately 7 inches outboard from the butt end of the blade and approximately 1.5 inches aft of the leading edge. The cause of the cracking was found to be a burr at the tip of the retention block tang, under the blade skin. The burr chafed on the inner surface of the skin, causing a crack. This amendment is issued to alter the wording of the requirement to reflect current practice. The background of the AD was also added. There is no change to the technical requirements or compliance. David Villiers Delegate of the Civil Aviation Safety Authority 4 August 2005