COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Agusta A109 Series Helicopters AD/A109/30 Gleason Crown Inspection 8/99 DM Applicability: A109A, A109AII and A109C helicopters, fitted with main transmission and Gleason Crown identified in Agusta Service Bulletin No. 109-109 dated 03 June 1999 and which have accumulated between 300 and 900 operating hours. Requirement: 1. Perform the aural inspection of the main gearbox in accordance with the instructions contained in Part I of Agusta Service Bulletin No. 109-109 dated 03 June 1999. Note: The word "auscultate" in the Agusta SB means "to listen to using a stethoscope". 2. Perform the non destructive test of the Gleason Crown (installed in the main transmission) in accordance with the instructions contained in Part II of Agusta Service Bulletin No. 109-109 dated 03 June 1999. Replace Gleason Crown as required by Agusta Service Bulletin No. 109-109. 3. Repeat the test at 2 above. Note: RAI AD 99-267 dated 10 June 1999 refers. Compliance: 1. Before next flight after the effective date of this Directive. 2. Not later than 50 operating hours following the effective date of this Directive. 3. Every three hundred operating hours up to and including nine hundred operating hours. This Airworthiness Directive becomes effective on 14 July 1999. Background: One case of a cracked Gleason Crown on an Agusta A109C helicopter has been discovered following an investigation into a reported unusual noise from the main rotor transmission system. This directive introduces a regular aural inspection and Non Destructive test to monitor for the presence of cracks in the Gleason Crown of certain helicopters and certain transmissions.