What was found
LEFT ENGINE TORQUE INDICATOR SURGED AND PROPELLER RPM INDICATOR FLUCUATED DURING TAKEOFF. CREW CONTINUED ON WITH THE TAKEOFF. THE FLUCUATION AND SURGE PROBLEMS CONTINUED AFTER T/O. THE CREW ELECTED TO RETURN TO THE FIELD. AIRCRAFT LANDED WITHOUT FURTHER INCIDENT. INSPECTED THE LT ENGINE AND NOTICED THAT THE MAIN CANNON CONNECTOR TO THE ELECTRONIC ENGINE CONTROL WAS LOOSE, TIGHTENED THE CONNECTOR AND GROUND CHECKED GOOD.