COMPRESSOR AIR BLEED OVERRIDE CONTROL SYSTEM

A compressor air bleed override control system is provided to bleed interstage air from the compressor of an aircraft turbine engine under the conditions during which a compressor instability, such as surge, is likely to occur. The override system includes an override valve control that is in communication with an altitude sensor to make the system operative above a preselected pressure altitude, but inoperative below the selected pressure altitude. The altitude sensor is in communication with the engine fuel control power lever, which is an indirect sensor of compressor speed, such that at speeds corresponding to a slow deceleration from a sufficiently high altitude, the compressor bleed valve will rapidly open. The system further measures the rate of movement of the power lever so that small but sufficiently rapid movements of the power lever, which are sustained for a selected period of time, will also cause the compressor bleed valve to open quickly. The period of time during which the bleed valve remains open is a function of the rate of movement of the power lever.