COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Eurocopter SA 360 and SA 365 (Dauphin) Series Helicopters AD/DAUPHIN/43 Main Rotor Head Frequency Adapter 10/96 Applicability: Model AS365N, N1, and N2 fitted with main rotor head frequency adapters: 1. P/N 704A33-640-031 (E1T2624-01A) or delivered in pairs under P/N 365A31- 1858-01, manufactured before the second quarter of 1991 (2T91) with a serial number equal to, or less than 8188; or 2. P/N 704A33-640-046 (E1T3023-01) or delivered in pairs under the P/N 365A31- 1858-02, manufactured before the second quarter of 1991 (2T91) with a serial number equal to, or less than 3122. Requirement: Action in accordance with Eurocopter AS 365 SB 01.00.44. Note: DGAC AD 96-117-040 refers. Compliance: Within 100 hours time in service after 12 September 1996, or prior to 12 March 1997 whichever occurs first. Background: Severe vibration has been found to be caused by separation of the elastomer and the centre metal section of the frequency adapters. The separation may be caused by a fault in the production process for certain frequency adapters.