The civil aerospace industry is moving towards the 'more electric aeroplane'. The benefits are reduced weight and reduced maintenance which will result in better fuel economy and lower flight cost per mile. One of the important technologies is fault tolerant yet power dense electrical drive systems which have very high reliability to meet safety-critical aircraft applications. The particular subject of this thesis is fault detection in permanent magnet synchronous machines. The specific target application is a 16kW, 15,000 rpm aircraft engine fuel pump drive that has previously been developed by the Power Electronics, Drives and Machines Research Group at the Newcastle University.