COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Partenavia P68 Series Aeroplanes AD/P68/42 Wing Upper Skin Stringers 2/96 Applicability: All P68 series aircraft up to S/N 400 inclusive. Requirement: 1. Modify and inspect the wing and engine nacelle between ribs 6 and 8 in accordance with paragraphs 2.1 and 2.2 of Partenavia Service Bulletin No 93. 2. Modify and inspect the wing upper surface between ribs 6 and 8 in accordance with paragraphs 2.3 and 2.4 of Partenavia Service Bulletin No 93. Compliance: 1. Action in accordance with Requirement 1 before 100 hours time in service after 1 February 1996 or before 500 hours time in service, whichever occurs later. Re- inspect at intervals not to exceed 300 hours time in service until modified in accordance with Requirement 2. For aircraft modified in accordance with Requirement 2, re-inspect at intervals not to exceed 500 hours time in service. 2. Action in accordance with Requirement 2 before further flight if cracked stringers are found during inspection in accordance with Requirement 1. Re-inspect at intervals not to exceed 2000 hours time in service. Background: Several cases of cracking of the wing upper skin stringers have been reported to the manufacturer. On one aircraft in Australia, during re-assembly after inspection in accordance with AD/P68/28, all four stringers were found to be cracked on both sides of the wing. This Directive requires installation of access panels for inspection and replacement of all stringers if any are found cracked.