COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Short SC7 (Skyvan) Series Aeroplanes AD/SC7/11 Air/Ground Lever Spring Heel Block - Inspection 8/79 Applicability: All models SC7 Series 3, 3A and 3M. Document: Shorts Alert SB No. 76-A56. Compliance: Within 25 hours time in service after 27 August 1979. Background: The air/ground lever spring heel block is to be checked for security. Loss of this block will permit inadvertent selection of the power lever into ground range.