COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES DHC-3 (Otter) Series Aeroplanes AD/DHC-3/31 Control Column Cracking 13/87 Applicability: All models. Requirement: Action in accordance with the Havilland Canada SB 3/39 Rev B. Compliance: In accordance with the criteria listed in the Requirement Document but prior to the issue of an initial Certificate of Airworthiness. Note 1. Canadian AD CF-82-34 refers. Note 2. An inspection is required whenever a parked aircraft is subjected to the adverse wind conditions descried in the Requirement Document. Background: There have been reported cracks in the lower welded assembly at the base of the control column. The cracking is attributed to ground gust loading of the elevator surfaces.