COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Moravan Zlin Z-242L Series Aeroplanes AD/Z-242L/1 Oil Sludge Valve 9/97 DM Applicability: All Zlin 242L aircraft serial numbers up to 0708 and aircraft serial numbers 0727 and 0728 incorporating an oil system sludge valve as detailed in Moravan Drawing Number L 242L.7100-04.00. Requirement: To prevent the possible leakage of oil from the engine, inspect the sludge valve for proper locking in accordance with Moravan Mandatory Service Bulletin Number Z 242L/25a. Note: Czech Republic Airworthiness Directive CAA - AD-2 - 029/97 refers. Compliance: Prior to further flight effective 2 July 1997. Background: This directive has been issued to require an inspection of the oil system sludge valve for proper locking. The requirement is in response to advice from the manufacturer of a manufacturing error which may cause failure of the valve and the loss of oil from the engine.