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 407/11 Door Locking Mechanism 10/99 Applicability: Model 407 helicopters, serial numbers 53000 through 53334. Requirement: Action in accordance with Bell Helicopter Textron Canada Alert Service Bulletin 407-99-30, dated 10 May 1999. Note: Transport Canada AD CF-99-19 refers. Compliance: Before 30 November 1999, unless already accomplished. This Airworthiness Directive becomes effective on 7 October 1999. Background: The manufacturer has received reports of in-service problems with the doors. A possibility exists for the locking mechanism to become completely disabled and could impede an emergency egress, should critical circumstances arise.