What was found
FLIGHT 4506 PIT-CRW. DURING CLIMB, CREW NOTICED THE LEFT ENGINE TORQUE FLUCTUATING +/- 30-40 PERCENT AT A POWER SETTING OF ABOUT 90-100 PERCENT. ALSO HAD AN ERRATIC LEFT PROP RPM. A SLIGHT YAW WAS FELT WHILE A MORE NOTICABLE ENGINE SURGE WAS HEARD. ALL OTHER ENGINE INDICATIONS WERE NORMAL. CREW DECLARED AN EMERGENCY AND STARTED THE RETURN TO PIT. CREW ENGAGED TORQUE MOTOR LOCK-OUT FOR THE LT ENGINE. THE PROBLEM WENT AWAY AFTER TML ENGAGED. AIRCRAFT RETURNED TO PIT SAFELY AND WAS TAKEN OUT OF SERVICE 2-8-03 AT 1355. AIRCRAFT FERRIED TO FWA 2-9-03, ARRIVED AT 1313.