What was found
ON A ROUTINE PREFLIGHT INSPECTION, THE LT HYDRAULIC ROLL CONTROL SERVO WAS DISCOVERED TO BE LEAKING HYDRAULIC FLUID AT THE PISTON SHAFT SEAL. THE LEAK COULD NOT BE DUPLICATED DURING GROUND TESTING WITH A HYDRAULIC POWER CART IAW THE MM INSTRUCTIONS. SUBSEQUENT FLIGHT TESTING REVEALED THE LEAK PERSISTING WITH A LEAK RATE SUSPECTED TO BE SLIGHTLY OUT OF LIMITS. OF PARTICULAR NOTE: THE LEAK COULD ONLY BE DUPLICATED WHILE ACTUAL FLIGHT LOADS WERE INDUCED. ASIDE FROM THE LEAK, THE HYDRAULIC SERVO WAS REPORTED TO BE FUNCTIONING NORMALLY. UNIT WAS REPLACED.