COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Douglas DC3 Series Aeroplanes AD/DC3/28 Reissue Applicability: All models. Hydraulic System - Modification 1/84 Document: Douglas SB No 239. Compliance: Unless already accomplished within 100 hours time in service after 31 May 1984. Background: This Directive is reissued with no changes to the requirement. In the event of an engine failure during the take-off phase, this modification ensures the availability of hydraulic pressure to raise the undercarriage if required.