Abstract: According to an aspect, a correction factor for a fuel flow of a fuel system of an engine is determined. A nominal fuel flow is determined based on a metering valve stroke. The correction factor is applied to the nominal fuel flow to produce an estimated fuel flow to control combustion in the engine.

Abstract: An aircraft system is provided that includes a fuel reservoir, a turbine engine and a fuel-to-fuel heat exchanger. The heat exchanger is fluidly coupled between the fuel reservoir and the turbine engine.

Abstract: A bowed rotor prevention system for a gas turbine engine includes a bowed rotor prevention motor operable to drive rotation of the gas turbine engine through an engine accessory gearbox. The bowed rotor prevention system also includes a controller operable to engage the bowed rotor prevention motor and drive rotation of the gas turbine engine below an engine starting speed until a bowed rotor prevention threshold condition is met.

Abstract: A method for actively calculating a capability of an electronically controlled valve is provided. The method including the steps of: a) operating the electronically controlled valve in accordance with a task; b) testing the electronically controlled valve in order to determine a range of movement of the electronically controlled valve in accordance with an initial gain, wherein the testing of the electronically controlled valve occurs after the valve has been operated in accordance with the task; c) determining a new gain required for providing a predetermined range of movement of the electronically controlled valve; and d) repeating steps a-c at least once, wherein the new gain is used to operate the valve in accordance with the task.

Abstract: A system and methods of estimating and controlling fuel flow in a gas turbine engine are disclosed. The system and methods include providing a metering valve and a pressure regulating valve. The system and methods further include determining a differential pressure error of the pressure regulating valve based on a metering valve inlet pressure, a discharge pressure, and a bypass fuel flow and determining a metering valve fuel flow based on a metering valve position and the differential pressure error.

Abstract: An aircraft system is provided that includes a fuel reservoir, a turbine engine and a fuel-to-fuel heat exchanger. The heat exchanger is fluidly coupled between the fuel reservoir and the turbine engine.

Abstract: The speed of a high-pressure turbine of a gas turbine engine may be determined using known centrifugal pump affinity relationships for a fuel pressure apparatus, fuel pressure apparatus input and output pressures, and gear ratios for a mechanical linkage between the high-pressure turbine and the fuel pressure apparatus. The technique avoids wear-related variations in gas pressure based measurements and also applies to fuel pressure apparatus using both single pump and multiple pump configurations.

Abstract: The speed of a high-pressure turbine of a gas turbine engine may be determined using known centrifugal pump affinity relationships for a fuel pressure apparatus, fuel pressure apparatus input and output pressures, and gear ratios for a mechanical linkage between the high-pressure turbine and the fuel pressure apparatus. The technique avoids wear-related variations in gas pressure based measurements and also applies to fuel pressure apparatus using both single pump and multiple pump configurations.