COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Piper PA-23 (Apache and Aztec) Series Aeroplanes AD/PA-23/85 Hydraulic Hose Inspection 6/86 DM Applicability: PA-23-150/160 Apache S/Nos. 23-1 to 23-2046 PA-23-235 Apache S/Nos. 27-505 to 27-622 PA-23-250 Aztec S/Nos. 27-1 to 27-8154030. Requirement: Action in accordance with Piper Service Bulletin No. 822. Compliance: Within 10 hours time in service after 19 May 1986. Background: A group of hydraulic hoses were manufactured using material that does not meet the pressure requirements for operation in the aircraft hydraulic system.