Disclosed herein is a method of automatically determining an operating condition of at least part of a gas turbine engine 10 for an aircraft, the method comprising: measuring one or more gas pressure waves by a gas pressure detector 401, wherein the gas pressure detector 401 is located in the gas turbine engine 10; and automatically determining, by a computing system, an operating condition of at least part of a gas turbine engine 10 in dependence on an output signal of the gas pressure detector 401.

A method of controlling a gas turbine engine including receiving an instantaneous thrust demand for current operation of the engine, determining the inlet flow rate and/or the pressure ratio within the compressor of the engine and determining whether the inlet flow rate and/or the pressure ratio match the working line for the compressor. The angle of one or more vane of the compressor is adjusted according to a closed control loop if the inlet flow rate and/or pressure ratio lie outside said desired range in order to adjust the inlet inflow rate and/or pressure ratio to meet the working line. The fuel flow to the engine combustor is adjusted concurrently in order to meet the thrust demand.

Method to operate a vacuum system comprising at least a first vacuum pump and a second vacuum pump wherein the first vacuum pump and the second vacuum pump are connectable to a vacuum chamber to maintain a set pressure inside the vacuum chamber. The first vacuum pump is a Variable Speed Drive pump wherein the first vacuum pump and the second vacuum pump are connected in series. The method comprises the steps of controlling the performance of the first vacuum pump and the performance of the first vacuum pump is controlled to be equal to or higher than the performance of the second vacuum pump while maintaining the set pressure in the vacuum chamber.

A method of evaluating compliance of a component of an aircraft engine with flow requirements has: obtaining experimental data from experimental testing on a prototype of the component; obtaining a digitized model of a production model of the component, the digitized model including digitized apertures having geometrical data corresponding to that of apertures defined in the production model; computing a nominal mass flow rate through the digitized apertures using the geometrical data and flow parameters from the experimental data; correcting the nominal mass flow rate of the digitized model to obtain a computed mass flow rate of the production model; and assigning at least one parameter to the production model, the at least one parameter indicative of installation approval of the production model of the component for installation on the aircraft engine when the computed mass flow rate is determined to be within a prescribed range of the flow requirements.

A method for controlling the clearance between the blade tips of a high-pressure turbine of a gas turbine aircraft engine and a turbine shroud, including the controlling of a valve delivering a stream of air to the turbine shroud, this method further including the following steps: the detection of a transient acceleration phase of the engine; the receiving of an item of data representative of the gas temperature at the outlet of the combustion chamber of the engine; a valve opening command, to deliver the air stream to the turbine shroud or to increase the flow rate of the delivered air stream, if the transient acceleration phase is detected and if the gas temperature at the outlet of the combustion chamber is greater than a first temperature threshold corresponding to a degraded clearance characteristic of an aged engine, this threshold being less than an operating limit temperature of the engine.

The method can include determining a mass flow rate W of working fluid circulating through the compressor stage, determining a control parameter value associated to the geometrical configuration of the variable geometry element based on the determined value of mass flow rate W; and changing the geometrical configuration of the variable geometry element in accordance with the determined control parameter value.

A flow rate per unit time of fuel fed to a gas turbine is calculated. A flow rate per unit time of air fed to the gas turbine is calculated. A turbine inlet temperature is calculated through use of a physical model formula expressing a relationship of input and output of thermal energy relating to a combustor of the gas turbine. A fuel distribution ratio for each of a plurality of fuel supply systems connected to the combustor is calculated based on the turbine inlet temperature.

A passive flow splitting system for use in a turbine engine control system to provide split fuel flow to two fuel manifolds to supply primary and secondary fuel injectors for the particular combustion zones thereof utilizing intentionally different split ratios dependent on ascending or descending combustion fuel flow is provided. The system includes a passive fuel divider valve (FDV) that includes a primary piston and a secondary piston. The primary piston is moveable independently from the secondary piston during a portion of its stroke, and is hydro-locked to the secondary piston during another portion of its stroke. An ecology valve is also provided to purge the fuel from the primary and/or secondary manifolds during different modes of operation. A transfer valve is included to control the position of ecology piston of the ecology valve.

A method of a control system (2200) controls an inductance motor in a blower including an impeller and volute using a pressure compensation control system. The control system may be implemented in a respiratory pressure therapy device. The control system may include a sensor configured to provide a pressure signal indicative of the pressure of a flow of fluid produced by the blower. A measured pressure may be compared to a set pressure to determine a pressure error. A slip frequency may be adjusted as a function of the pressure error in an attempt to eliminate or minimise the pressure error.

A gas turbine engine includes a main compressor section. A booster compressor includes an inlet and an outlet. The inlet receives airflow from the main compressor section and the outlet provides airflow to a pneumatic system. A recirculation passage is between the inlet and the outlet. A flow splitter valve controls airflow between the outlet and the inlet through the recirculation passage for controlling airflow to the pneumatic system based on airflow output from the booster compressor. A bleed air system for a gas turbine engine and a method of controlling engine bleed airflow are also disclosed.