Aiming at the surge fault of a turboshaft engine,through the detailed analysis and comparison of steady-state test data and dynamic test data,the fault sequence is confirmed,and the fault reason is accurately lo-cated as the accumulation of air in the cavity structure of the low-pressure pump under the condition of fuel heat-ing,which leads to the continuous pressure drop and low pressure of the fuel.Insufficient fuel pressure leads to insufficient fuel supply,causing the engine to quickly stall.In order to maintain the constant regulation law of the engine power turbine,the electronic control system rapidly supplies oil,resulting in rich oil,and the sharply rising gas temperature leads to the formation of"thermal throttling"at the gas turbine inlet,causing engine surge.The fault recurrence is verified by semi physical simulation and whole machine test,and the improvement measures are put forword.The analysis and troubleshooting of this fault can provide a certain reference for the troubleshooting of other models and the design of fuel pump.