The aircraft departed Ternate Airport, Indonesia at 13.55 LT on a domestic passenger service to Gebe. The pilot in command acted as pilot flying and the second in command acted as pilot monitoring. During climbing while passing 6,000 feet, both pilots saw the no. 1 propeller flying forward from the left side of the aircraft. The pilot sensed that the aircraft began to yaw and countered this movement by using the rudder pedal. The pilot checked the instruments and saw that the left engine torque was zero and the oil temperature began to rise. The pilots then shut down the left engine by closing the fuel shut off valve. The aircraft returned to Ternate and landed safely. Contributing Factors: – The failure of the hub half was due to fatigue crack which was undetected as the Non Destructive Inspection has exceeded 154 cycles form the next schedule of inspection. – The exceeding of flight cycles was due to transfer error of data and missinterpretation of inspection interval. – The recording column of the Propeller Log Book available in flight hour only, it may miss lead the interpretation of the maintenance personnel of the inspection interval based on flight hour only instead of both flight hour and flight cycle.