COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell Helicopter Textron Canada (BHTC) 407 Series Helicopters AD/BELL 407/6 Engine to Transmission Driveshaft Replacement 5/99 Applicability: Bell (BHTC) Model 407 helicopters, serial numbers 53000 and 53002 through 53066. Requirement: Replace driveshaft part number 206-340-300-103 with driveshaft part number 206- 340-300-105 in accordance with the instructions in BHTC Alerts Service Bulletin (ASB) 407-98-19 dated 19 June 1998. All removed driveshafts are to be rendered unusable or identified as unairworthy and quarantined from airworthy parts. Note: Transport Canada Airworthiness Directive CF-98-25R1 refers. Compliance: Within the next 50 hours flight time after the effective date of this Directive. This Airworthiness Directive becomes effective on 20 May 1999. Background: A recent evaluation of the engine to transmission driveshaft concluded that the current configuration does not meet certification criteria. Replacement of the driveshaft has therefore been mandated to remove the non compliant component.