COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Cessna 340 Series Aeroplanes AD/CESSNA 340/33 Exhaust System Components - Inspection 1/99 TX Applicability: Model 340A aeroplanes, serial numbers 215 through 1817 that have had an exhaust system WYE tube changed since 01 May 1998. Requirements: 1. Establish the part number of the exhaust system WYE tube fitted to the aircraft by search of the aircraft records or by physical examination of the component. 2. Remove and replace exhaust system WYE tubes P/N 9910299-25 or P/N 9910299- 26 with exhaust system WYE tubes P/N 9910299-8 (for P/N 9910299-25) or P/N 9910299-9 (for P/N 9910299-26) or any other WYE tube that is approved by the aircraft manufacturer. Note: US FAA Priority Letter 98-24-14 dated 13 November 1998 refers. Compliance: 1. Before further flight after receipt of this Airworthiness Directive. 2. Before further flight if defective components are identified. This Airworthiness Directive becomes effective on 20 November 1998. Background: The FAA has received reports of five instances where the engine exhaust components in the WYE tube installed on certain Cessna aircraft were manufactured without welds. These non-welded areas lead to leaks in the exhaust system on the turbocharged engine installations on these aeroplanes. The heat from the leaks in the exhaust system have caused aluminium fuel lines located immediately behind the firewall to burst. This condition has come about due to a quality control problem at a sub contractor. Cessna has returned all existing inventory to the sub contractor, however it is known that approximately 25 WYE tubes have been distributed to the field since May 1998. This Directive issues instructions to identify and remove from service the defective components. This defect is considered to be an urgent safety of flight issue and hence the inspection must be completed before further flight.