Abstract: A system comprises an aircraft hydraulic system motor, a position sensor, and a programmable controller. The aircraft hydraulic system motor includes a rotor whose position is detected by the position sensor. The position sensor produces an output representative of that position. The programmable controller is configured to receive the output of the position sensor and calculate an estimated velocity of the aircraft hydraulic system motor based on the output of the position sensor. The calculation of the estimated velocity comprises determining both a high bandwidth velocity estimation and a low bandwidth velocity estimation. The programmable controller is additionally configured to compare the estimated velocity to a desired velocity and direct the aircraft hydraulic system motor to increase or decrease velocity based on the comparison.

Abstract: Methods of cleaning internal portions of additively manufactured components are provided, together with an apparatus for carrying out the cleaning. The methods use an impacting element which is contained within the internal portion and the component is vibrated to clean material from the component and leave one or more hollow portions. Various embodiments for retaining the impacting element are set out, which preferably use a grid which allows loosened powder to fall out of the component and, optionally, be recycled for use in further manufacturing processes. The methods are described in relation to components for gas turbine engines but have wider application in relation to any additively manufactured component in which it is desired to have a hollow internal portion.