COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Eurocopter AS 355 (Twin Ecureuil) Series Helicopters AD/AS 355/8 Main Gearbox Filter - Inspection 3/83 Applicability: All model AS 355 helicopters, having the main gearbox fitted with a TEDECO magnetic plug, Part Number B4439 with electrical indication (optional SB 63.02 refers) and not modified in accordance with A.M.S. 07.1211. Document: AS 355 SB 05.07. Note: Bureau Veritas AD 82-180-9(B) refers. Compliance: At periods not exceeding 100 hours time in service after 31st March 1983. Background: The manufacturer advises of the need to reduce the inspection interval for the main gearbox oil filter, on helicopters fitted with the TEDECO magnetic plug installation.