COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Christen Industries A-1 (Husky) Series Aeroplanes AD/HUSKY/1 Seat Back 4/91 Applicability: Model A-1 with serial numbers 1001 through 1125. Requirement: Action in accordance the technical requirements of FAA AD 90-20-05 Amdt 39-6741. Note: Christen SB 2 refers. Compliance: As specified in the Requirement Document with revised effective date of 18 April 1991; unless already accomplished. Background: A recent fatigue failure of the front seat resulted in the pilot falling backwards against the rear seat flight controls with subsequent loss of control of the aircraft. The actions in this AD will prevent failure of the front seat back assembly.