COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Hiller UH-12 Series Helicopters AD/HILLER 12/26 Rotor Tachometer Generator - Replacement 5/79 Applicability: Model UH-12D and UH-12E helicopters with Soloy Turbine Conversion using 22A580 tachometer generators in the rotors position. Document: 1. Soloy Conversions SB 03-560; or 2. FAA AD 79-03-07. Compliance: Within 200 hours' time in service after 31 May 1979. Background: The new rotor tachometer generator type is expected to reduce the number of failures being experienced with the present generators. The repeated execution of emergency procedures involving unnecessary external load deployment and full autorotation following false low rotor speed warning system activation should be avoided, thereby reducing the hazard to the aircraft.