COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Kitfox Series Aeroplanes AD/KITFOX/2 Flaperon Mass Balance 5/90 Applicability: All models not fitted with mass balance system (WMB 40). Requirement: Carry out installation of flaperons mass balance system (WMB 40) in accordance with wing construction section of Denney Aerocraft Company, Kitfox Assembly Manual, or other scheme approved by the Authority. Compliance: Prior to 30 June 1990. Background: Flutter has occurred in both overseas and local aircraft. The company has made standard the fitting of a flaperon mass balance system and provides a kit for retrofit to aircraft not so equipped.