COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell Helicopter Textron Canada (BHTC) 206 and Agusta Bell 206 Series Helicopters AD/BELL 206/141 Hydraulic Relief Valves 14/98 Applicability: Bell Helicopter Textron Canada(BHTC) Model 206L-4 helicopters Serial numbers 5201 through 52208. Requirement: Replace hydraulic relief valve P/N 206-076-036-101 with P/N 206-076-036-105 in accordance with BHTC Alert Service Bulletin (ASB) 206L-98-111. Ensure proper functioning of the flight controls in accordance with BHTC ASB 206L- 98-111 dated 24 July 1998. Note: Transport Canada AD CF-98-34 Bell refers. Compliance: Unless previously carried out within 300 hours Time in Service from the issue of this AD but no later then 31 December 1998. This Airworthiness Directive becomes effective on 31 December 1998. Background: There was a manufacturing defect found on hydraulic relief valve P/N 206-076-036- 101 which could lead to an intermittent loss of hydraulic pressure to the flight controls.