COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES DHC-6 (Twin Otter) Series Aeroplanes AD/DHC-6/64 Elevator Pushrod Ball Ends 7/90 Applicability: All models. Requirement: Remove the pushrods (P/N C6CF 1466-1 or C6CF 1141-1) from the aircraft. Remove the rod ends from both ends of the pushrod and inspect for corrosion, damage, freedom of rotation and cracks, in accordance with Transport Canada Emergency AD CF-90-10. Compliance: Within the next 25 hours time in service or five days, whichever occurs first, after 14 May 1990, unless accomplished within the previous 21 days. Background: Fatigue failure of an elevator pushrod ball end has occurred in service. It is suspected that the cause may have been related to seizure of the ball and/or bending or misalignment.