Some experimental stages of electrostatic monitoring explorative experiments which used the engine test bed and a certain small turbojet engine were conducted. The characteristics of electrostatic signal of the turbojet engine's exhaust gas were obtained

and the electrostatic monitoring technology's ability of monitoring the engine gas path mechanical faults was verified.Then

the result of the next research shows that electrostatic signal of the turbojet engine's exhaust gas may change a little with the engine conditions.There are some evidences obtained by the analysis of the electrostatic signal in stage 102 showing that the activity level changes with the engine conditions

and the activity level is a characteristic parameter of the charged micronized particles in the turbojet engine's exhaust gas.In the process of engine test from stage 102 to stage 108

there were some faults such as engine combustion chamber carbon deposition fault

mild ablation breakdown and lub oil leaking in gas path.There were some changes in electrostatic whole level of engine's exhaust gas which can be found by analyzing signal statistical and long time domain to make characteristic parameters of the electrostatic signal like active level and positive (negative) event rate as early-warning parameters corresponding with these faults.