What was found
CLIMBOUT, 8 TO 10 UNCONTL RUDDER INPUTS, STRONG ENOUGH TO FEEL ACFT RESPOND. TURNED AUTOPILOT & YAW DAMPER ON & OFF, NO EFFECT. PROBLEM DISAPPEARED. CLIMBOUT, NR 1 ENG SURGED THRU 18,000 FT. TURNED AUTOTHROTTLE ON & OFF, NO EFFECT. REACHING 18000 FT ENG RAN SMOOTH. REPLACED RUDDER PCU, RIGGED & PERF OPS CHK OF RUDDER PCU, YAW DAMPER COUPLER & FOUND NO DISCREP & ACCOMP FLT CONTL MOVEMENT CHK. THE DFDR & CVR WERE REMOVED FOR READ OUT. NO SIGNIF RUDDER MOVEMENT OR YAW OBSERVED. READ OUT SHOWED FLUX OF NR 1 ENG BEGUN 18000' & STAB 24,000'. PERF PWR ASSURANCE CHK & BORESCOPE INSPEC OF NR 1 ENG & PERF TROUBLESHOOT FOR SURGING ENG, NO FAULTS FOUND. ACCOMP TEST FLT, NO ENG SURGE OR UNCONTL RUDDER INPUT.