Abstract: Fault detection of measuring channel in aeroengine Full Authority Digital Electronic Control (FADEC) system is investigated,especially aroundback detection is researched.The causes of the measuring channel faults have been revealed,meanwhile,the principle figure of the aroundback detection is also provided.The simulation of A/D transformer for the aroundabck detection simulation tests indicates that multi-aroundback detection range is larger than singe-aroundback one.When the aroundback detection processes small signals,it may cause error.The accuracy is 100% in detecting short circuit and open circuit by aroundback detection.