Abstract: An asset management system includes a plurality of assets, a plurality of sensors for determining one or more operating conditions for each of said assets and one or more processors for determining a risk profile for each of the assets over time. The processor is arranged to calculate a risk index value for each asset from the risk profile, the risk index providing a relative indicator of the need for maintenance of an asset. A maintenance queue is established and assets are entered into the queue once the risk index value for that asset matches or exceeds a predetermined threshold value, the position of the asset in the queue being determined based upon the value of its risk index.

Abstract: In an engine cooling system wherein supply pipes 40, 50 supply cooling fluid (e.g.: air) to the turbine 20 from a compressor bleed 10, upon failure of one of the supply pipes 50 the backflow of cooling fluid from the turbine to the point of failure may be stemmed by use of a vortex amplifier 140, 160 connected into each supply pipe 40, 50, the tangential ports of the vortex amplifiers being interconnected by a balance pipe 180. This allows the total minimum bleed flow rate of cooling fluid supplied to the turbine from the compressor bleed to be reduced.