AD 68-17-03

68-17-03 PILATUS: Amendment 39-634. Applies to all Model PC-6 Series Airplanes. Compliance required as indicated. To detect cracks in the rudder end rib, accomplish the following: (a) Within the next 50 hours time in service after the effective date of this Airworthiness Directive and thereafter at intervals not to exceed 50 hours time in service from the last inspection, inspect the rudder end rib P/N 6302.27 for cracks with the aid of a mirror. (b) If cracks are detected during any inspection prescribed in paragraph (a), replace the rudder end rib before further flight with a modified rudder end rib, P/N 6302.26 Pos. 2; channel reinforcement, P/N 113.40.06.002, and torque tube, P/N 113/40.06.003, in accordance with Pilatus Service Bulletin No. 80, dated April, 1968, or later Swiss Federal Air Office approved Revision or FAA approved equivalent. (c) The repetitive inspections required by paragraph (a) may be discontinued after the modified rudder end rib has been installed. This amendment becomes effective August 19, 1968.