COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F27 Series Aeroplanes AD/F27/122 Amdt 1 MLG Upper Member 12/91 Applicability: Model F27 series with serial numbers 10102 through 10684, 10686 and 10687, 10689 through 10692. Requirement: Inspect and modify in accordance with Fokker SB F27/32-162. Note: RLD AD 91-041 refers. Compliance: Before 1 January 1992. (Same as previous issue of this Directive.) Background: Several main undercarriage upper members were found on inspection to have a fatigue crack at the intersection of the side face and the cross bore. Therefore Fokker is calling for a one time inspection of the rest of the fleet, and a rework to radius the edge of the cross bore to prevent further cracking. Amendment 1 is raised to align this Directive with the related RLD AD, which calls up the above Fokker bulletin, and in doing so now includes the Mk 500.