COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Partenavia P68 Series Aeroplanes AD/P68/35 LH and RH Muffler Assemblies 6/91 Applicability: All models excluding the 'TC' series. Requirement: Action in accordance with the Technical Requirements of RAI AD No 91-125/P68- 42. Note: Partenavia Service Bulletin No 83 refers. Compliance: In accordance with the Requirement Document with revised effective date 30 June 1991. Background: Due to the possibility of carbon monoxide entering the aircraft cabin through the heating system a repetitive inspection of the muffler assemblies has been introduced.