COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Kitfox Series Aeroplanes AD/KITFOX/1 Wing Structural Integrity 5/90 Applicability: All models. Requirement: Carry out an inspection to ascertain structural integrity of the bonding of wing ribs to front tubular spar, using the following method: Remove wing tips. Grasp wing structure at tip with one hand at leading edge and other as far aft as possible, and whilst applying a reasonable torsional load, have an observer noting any abnormal wrinkling of wing fabric covering, between, and at all wing rib stations. Repeat torsional load in opposite direction and further observe. Any abnormal wrinkling is to be investigated by removal of fabric from suspect area, before further flight. Note: The use of a more positive method for attachment of wing ribs to front spar tube, to a scheme approved by the Authority, would be considered terminating action for this Directive. Compliance: For aircraft that have exceeded 100 hours total time in service or 1 year since building at 17 May 1990 - Prior to 30 June 1990, and thereafter at intervals not exceeding 100 hours time in service or 12 calendar months, whichever occurs first. For aircraft that have not exceeded 100 hours total time in service or 1 year since building at 17 May 1990 - Prior to exceeding 100 hours time in service or 1 year since building, whichever occurs first, and thereafter at intervals not exceeding 100 hours time in service or 12 calendar months whichever occurs first. Background: Doubt exists as to the durability of the bonding of wing ribs to front spar tube.