What was found
(CAN) ON APRIL 23, 2007 DURING A TEST FLIGHT FOR MAINTENANCE THAT WAS PERFORMED, THE PILOT EXPERIENCED AN UNCONTROLLED YAW TO THE RIGHT WHILE IN A 4 FOOT HOVER. THE HELICOPTER WAS IMMEDIATELY SET DOWN ON THE TARMAC. THERE APPEARED TO BE A STEP WORN IN THE INTERNAL WORM GEAR SPLINE OF NUT ASSEMBLY P/N 204-010-765-001 THAT MAY HAVE AFFECTED THE RIGGING PROCEDURE THAT WAS ACCOMPLISHED THE NIGHT BEFORE. NO DAMAGE TO HELICOPTER, CARS 625 APPENDIX G WAS PERFORMED AT THE SCENE WITH NO REPORTED DEFECT. ENTIRE QUILL ASSEMBLY WAS REPLACED; AIRCRAFT RECEIVED FURTHER INSPECTION AND RE-RIGGED TAIL ROTOR ASSEMBLY AND TEST FLOWN WITH NO DEFECT. TSB WAS NOTIFIED AND HAVE NOT FINISHED THEIR INVESTIGATION. PRODUCT SUPPORT