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) 206 and Agusta Bell 206 Series Helicopters AD/BELL 206/165 Main Rotor Latch Bolts - Replacement 2/2007 TX Applicability: All Agusta helicopters AB206A and AB206B series, with Main Rotor latch bolts P/N 206-010-169-1/-3 or P/N 206-011-122-3 installed. Requirement: 1. For main rotor hub assemblies that have accumulated less than 1200 hours time in service (TIS) and are fitted with bolts P/N 206-010-169-1/-3 or 206-011-122-3 which have never been replaced, replace the bolts with new bolts P/N 206-011-260-103. 2. For main rotor hub assemblies that have accumulated less than 1200 hours time in service (TIS) and bolts P/N 206-010-169-1/-3 or 206-011-122-3 have been replaced; and main rotor hub assemblies that have accumulated 1200 flight hours or more, replace latch bolts with new bolts P/N 206-011-260-103. Note: EASA AD 2006-0371-E and Agusta Alert Bolletino Technico 206-241 dated 5 December 2006, or later EASA approved revision, refer. Compliance: 1. Before accumulating 1200 hours time in service (TIS), but not later than 25 January 2007, whichever occurs first. 2. Within the next 10 hours time in service (TIS) after 18 December 2006, but not later than 25 January 2007, whichever occurs first. However, if it can be determined that bolts P/N 206-010-169-1/-3 and P/N 206-011-122-3 have less than 1200 hours time in service (TIS), they can be replaced with new latch bolts P/N 206-011-260-103 upon accumulating 1200 hours time in service (TIS), but not later than 25 January 2007, whichever occurs first. This Airworthiness Directive becomes effective on 18 December 2006. Background: A new fatigue analysis of the latch bolts has shown that their fatigue life is less than desired. Hence, the bolts are being replaced with a new bolt with a more acceptable fatigue life. James Coyne Delegate of the Civil Aviation Safety Authority 15 December 2006