Abstract: A robust fault detection filter design method for faults in the actuator of a jumbo jet transport aircraft is proposed by considering how the structural parameters of the transport aircraft plant and its flight control system vary with flight altitude and Mach number, and how the measure signals are disrupted by noise. The objective is to find a parameter-vaying filter that makes the residual system fulfill a parameter varying mixed H_∞/H_- index. Using loop-shaping theory, the mixed index is transformed into a parameter-varying H_∞ index. The LFT tool is then employed to transform the above problem into a H_∞ robust performance problem for an LTI system with structured uncertainty, and the sufficient conditions for the existence of the filter are achieved via scaled bounded real lemmas. The parameters of the LPV filter for fault detection are obtained by the Matlab SDP toolbox. This LPV filter has the same varying parameter structure as the monitored plant, and it has adaptive capability for the varying parameters. Finally, a simulation example of the elevator surface injury of a B747-100/200 jumbo jet is illustrated to demonstrate the practical effect of the proposed approach.