A turboshaft engine is a variant of a jet engine that has been optimized to produce a shaft power to drive machinery instead of producing thrust. Turboshaft engines are most commonly used in applications that require a sustained high power output, high reliability, and small but powerful light weight engines, inclusive of helicopters, auxiliary power units, boats, ships, tanks, hovercraft, and stationary equipment. Mostly occurred problems in turboshaft engine is negative power margin, thermal margin, low power margin, torque pressure, Vibrations, Uncontrolled Acceleration, stall during acceleration, failure to accelerate properly etc. We are considering engine, that is single shaft turbine engine, with two stage axial compressor, one stage centrifugal compressor, reverse flow combustion chamber and one axial turbine with maximum output power of 805 KW. Lower power margin is the most commonly occurring problem in turbo shaft engine that is used in helicopters. It is caused due to heavy contaminations in air path which leads to fouling. This also results in reduced air flow of compressor which leads to lower power; along with other reasons for lower power is damage of hot core components like power turbine blades and impeller. Low power margin is defined as reduction of output shaft power below the minimum required power to lift the helicopter. The engine encounter with low power is confirmed by pilot by measuring the torque with corresponding altitude and ambient temperature. If the result is not matching with the requirements then engine is sent to test bed to find out the problem. The low power engine received from customer is confirmed by testing the engine in test bed, if power loss is within the acceptable limit then compressor wash is carried out through which 25% to 35% power is regained. After compressor wash if power is not regained then the engine is sent to Repair and Overhaul division and snag is rectified and sent back to test bed for final analysis. If engine is regains the power, then the engine will be dispatched. The engine performance is analyzed through graphs mainly Power vs rpm, during testing the parameters, power, mass flow rate, delta pressure, GG rpm, PT rpm, ambient temperature etc. are calibrated in test bed using FADEC system. In this paper we compare the power losses due to power turbine blade life cycle completion, impeller damage and chipping of blade found on fist axial compressor, rectification of snags, procedure followed to rectify the snags, final engine performance comparison and to confirm which snag because more power loss.