This paper reports work performed to support the development of condition monitoring strategies through extensive use of simulation. The aim is to define and implement a methodology that makes the development of lumped-parameter models more efficient and straightforward. This is achieved by considering the model architecting and the approach adopted for fault injection early in the process. Various options are proposed and compared for both these activities. The Bond-Graph formalism is extensively used for its ability to focus on the model structure and interfaces, the nature of the phenomena considered, and potential causality issues. The interest of the proposed methodology is illustrated with the example of a pressure-compensated axial piston pump that supplies the flight control actuators in helicopters. The pump model architecting and the fault injection are presented, with special attention to jamming and erosion of the pump compensator valve. From these examples, it is shown that the proposed methodologies provide an efficient model-based means of identifying fault signatures and implementing low-cost condition monitoring features in an industrial context.