COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES DHC-6 (Twin Otter) Series Aeroplanes AD/DHC-6/41 Wing Tip Bonding - Modification 5/76 Applicability: All models with S/Nos. 1 to 430 incorporating wing tip strobe lighting. Document: 1. De Havilland SB No. 6/318. 2. Canadian AD CF-76-04. Compliance: Within 100 hours time in service after 30 June 1976.