COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Cessna 208 Series Aeroplanes AD/CESSNA 208/8 Engine Mount Ring 7/90 Applicability: Models 208 and 208A serial number 20800001 to 20800130. 208B serial number 208B0001 to 208B0086. Requirement: 1. Visually inspect the lower portion of the engine mount ring for cracks and misalignment and: 1. replace any ring that is visibly misaligned or has a crack larger than 43 mm (1.7"), or b. where a crack is shorter than 43 mm (1.7") repair in accordance with Model 208 Maintenance Manual P/N 02076-2-13. 2. Replace nose wheel shimmy damper P/N 2643007-1 or 2 with shimmy damper P/N 2643090-1 in accordance with Cessna SB CAB88-14. Note: FAA AD 90-05-04 refers. Compliance: Within 100 hours time in service after 12 July 1990 or at the next inspection for Maintenance Release issue after 12 July 1990 whichever is the later. Background: There have been reports of engine mount cracking that has been attributed to nose wheel shimmy. If allowed to develop the loss of mount stiffness may result in whirl mode flutter of the propeller/powerplant system. Either the cracking or the flutter could cause the engine to separate from the airframe.