COMMONWEALTH OF AUSTRALIA (Civil Aviation Safety Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section. Cessna 120 and 140 Series Aeroplanes AD/CESSNA 120/12 Carburettor and Cabin Air Heater Muffs 12/2003 Applicability: All Cessna 120 and 140 aeroplanes equipped with Cessna welded exhaust muffler assemblies where the exhaust muffler assemblies are fabricated by welding the exhaust stacks to the muffler. Requirement: 1. Remove the carburettor air heater muff and cabin heater muff and inspect the muffler assemblies for evidence of cracks paying particular attention to the areas of the mufflers and stacks adjacent to where the exhaust stacks and tailpipe are welded to the muffler assembly. 2. Any placard calling for an inspection of the mufflers every 100 flight hours should be revised to call for the inspection every 25 flight hours. Note: FAA AD 48-25-02 refers. Compliance: 1. Initial inspection within 25 flight hours from effective date of this Directive, or 25 flight hours from the last inspection, thereafter at intervals of 25 hours. 2. At the first inspection of the muffler assemblies detailed in this Directive. This Airworthiness Directive becomes effective on 27 November 2003. Background: Cracking of the heater muff could lead to hazardous gases entering the cockpit. Jim Coyne Delegate of the Civil Aviation Safety Authority 14 October 2003 The above AD is notified in the Commonwealth of Australia Gazette on 5 November 2003. Page 1 of 1