What was found
(CAN) WHILE ON A TEST FLIGHT, NOTICED THE RPM ON THE RIGHT ENGINE BEGIN TO DROOP. WHEN THE RPM DROPPED BELOW 94 PERCENT SELECTED THE CONDITION LEVER TO THE FEATHER POSITION AND SECURED THE ENGINE AS PER THE EMERGENCY CHECKLIST. THEN RETURNED TO RED DEER AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND THE HYDRAULIC FITTING B-NUT ON THE PROPELLER NEGATIVE TORQUE SIGNAL (NTS) SOLENOID LOOSE AND THE ENGINE OIL WAS LOW. THE NUT WAS TIGHTENED OIL TOPPED OFF. ENGINE LEAK CHECKED AND RETURNED TO SERVICE.