What was found
AFTER TAKEOFF WHILE CLIMBING THROUGH 8000 FT AND IN A LEFTT TURN, EXPERIENCED SEVERAL ABRUPT UNCOMMANDED YAW MOVEMENTS AND JOLTS THAT OCCURRED SEVERAL TIMES. AIRSPEED APPROXIMATELY 240 KTS. A SHORT TIME AFTER THAT, RECEIVED A MASTER CAUTION AUTO FLT RUDDER TRIM 1 FAULT. THE RUDDER WAS HARD TO CONTROL. DECLARED AN EMERGENCY & LANDED. R & R THE RUDDER TRIM ACTUATOR 10CC IAW AMM 27-22-51-401. OPS CHECKED IAW AMM 27-22-00. A SUCCESSFUL CAT B ACCEPTANCE FLIGHT WAS ACCOMPLISHED BEFORE THIS ACFT WAS RETURNED TO SERVICE.