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 206/80 Fuel Feed Tube and Vent Tube - Replacement 1/80 Applicability: All models 206L and 206L-1. Document: Bell Alert SB No. 206L-79-7. Compliance: Within 100 hours time in service after 31 January 1980. Background: Moisture accumulation in the insulating material adjacent to the fuel feed tube and a fuel vent tube can cause corrosion to the extent of the tube wall penetration.