What was found
7-10 MILES FROM KFLG THE LEFT ENGINE BEGAN TO SURGE 50-100 FT/LBS ON THE TORQUE. NO OTHER FLUCTUATIONS ON THE LEFT ENGINE GAUGES WERE OBSERVED. THIS FLUCTUATION WAS FIRST NOTICES AUDIBLY. THIS OCCURRED UPON REDUCING THE THROTTLES TO 400 FT/LBS. AT APPROXIMATELY 4-5 MILES FROM KFLG THE LEFT ENGINE BEGAN TO SURGE 300-400 FT/LBS. NO OTHER FLUCTUATIONS CAN BE RECALLED FROM MEMORY ON THE OTHER GAUGES DUE TO SUN GLARE AND PROXIMITY TO LANDING. THE THROTTLE SETTINGS WERE BROUGHT BACK TO 200 FT/LBS PRIOR TO THESE SURGES. BRINGING THE THROTTLES TO FULL IDLE MADE THE SURGE SPREAD HIGHER ON THE LEFT ENGINE. PERFORMED A GROUND OPERATIONAL CHECK. ADJUSTED BOTH L/H AND R/H PROPELLER RPM ADJUSTMENT SCREWS 2 TURNS CLOCKWISE TO REDUCE MAX RPM. GROUND FUNCTIONAL CHECKS PERFORMED WITH SATISFACTORY RESULTS IAW BLACKHAWK DOCUMENT NO. 200710-30 REV 1R ENGINE RIGGING FOR CONTROL PROCEDURES. OPERATIONAL CHECK FLIGHT PERFORMED FOR L/H AND R/H PROP RPM ADJUSTMENTS AND L/H ENGINE SURGING AND WAS FOUND TO BE SATISFACTORY