COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Lycoming Piston Engines AD/LYC/85 Amdt 1 Exhaust Assembly 10/96 Applicability: Textron Lycoming TIO-540-S1AD engines. Requirement: To prevent cracking or distortion of the engine exhaust system flanges, V-band couplings and pipes which could result in an engine compartment fire and smoke entering the cabin, accomplish the following requirements: 1. a. Modify the crossover exhaust system in accordance with the requirements of Part II of Textron Lycoming Service Bulletin (SB) Number 484, and b. Install a one piece exhaust pipe and manifold retainer clamp in accordance with the requirements of Textron Lycoming SB No. 499B. 2. a. Inspect the exhaust system for heat damage, distortion, cracks or excessive wear in accordance with Textron Lycoming SB No. 484, and b. Inspect the exhaust system for clearance dimensions, proper fastener torque and slip joint engagement in accordance with Textron Lycoming SB No. 499B. 3. Repair or replace damaged parts identified during compliance with Requirement 2 of this directive. Note: FAA Airworthiness Directive 91-21-01R1 refers. Compliance: Requirement 1: Unless previously accomplished, within 25 hours time in service after 12 September 1996. Requirement 2: At intervals not to exceed 130 hours time in service, effective 12 September 1996. Requirement 3: Before further flight, effective 12 September 1996. Background: This directive was originally issued in October 1989 to require the inspection and modification of the exhaust system crossover pipe. The requirements addressed reports of accidents, incidents and defects related to the TIO-540-S1AD exhaust system. This amendment reflects advice from the manufacturer of reports of exhaust system defects in engines complying with the original issue of this directive. This amendment adds a further modification of the exhaust system by mandating the installation of a single piece pipe and a supporting clamp and an additional inspection procedure to cover the additional modification. The original issue of this Airworthiness Directive became effective on 4 August 1989.