COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Piaggio P166 Series Aeroplanes AD/P166/20 Hydraulic Pressure Gauges - Replacement 8/62 Applicability: All model P166. Document: Piaggio SB P166-27. Compliance: Forthwith.