1. A supervising system for supervising the function of an assembly comprising a number of interworking parts, said system comprising At least a first detector for detecting a physical property of an entity of the system and providing measurement data about the physical property; At least a first determining means for determining the status of said entity; said supervising system comprising filter means arranged to receive measurement data from the at least first detector, filter said measurement data and output a signal indicating if said entity is faulty in dependence of said filtered measurement data; and in that the determining means is arranged to receive said output signal from a least a first and a second filter means, co-ordinate said output signals and, on the basis of said co-ordination, determine whether a fault report should be generated for the entity.