What was found
SEA FLIGHT NR 2053, DURING NORMAL SINGLE ENGINE TAXI WITH NR 1 PROP FEATHERED POWER LEVERS SET BETWEEN DISC AND FLIGHT IDLE. UPON MOVING NR 1 CONDITION LEVER FROM START/FEATHER TO MAX, NR 1 TORQUE INCREASED RAPIDLY TO 30 PERCENT TORQUE. ENGINE STABILIZED AFTER UNFEATHERING WITH NORMAL SHUTDOWN. MAINTENANCE COMPLIED WITH PCU HEALTH HECK NO DEFECTS NOTED. SET POWER LEVER AND CONDITION LEVER AS PER DISCREPANCY COULD NO DUPLICATE THE PROBLEM. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.