COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pilatus Porter PC-6 Series Aeroplanes AD/PC-6/34 Additional Modifications for Compliance with Requirements for Issue of Certificate of Airworthiness 7/72 Applicability: Model PC6-H2. Requirement: 1. Modify each front seat restraint installation by fitting a safety harness in accordance with a scheme approved by the Secretary. 2. Install a placard indicating the location of the Flight Manual. 3. Calibrate and install a placard adjacent to the fuel quantity gauges. 4. Modify the external power connection circuitry to prevent inadvertent connection of reverse polarity or disconnect the external power system from the aircraft electrical system. Compliance: Before 31 August 1972.