COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Gates Learjet 24 & 25 Series Aeroplanes AD/LEARJET/19 Aileron Lower Skin - Inspection 2/80 Applicability: All model 23 with S/Nos. 23-003 to 23-099; All model 24 with S/Nos. 24-100 to 24-357; All model 25 with S/Nos. 25-003 to 24-291. Document: Gates Learjet SB No. 23/24/25-295. Compliance: Within 100 hours time in service after 31 March 1980. Background: The drain holes in the aileron lower skin may not be correctly installed or serviceable.