Multi-engine aircraft power and propulsion systems and methods of restarting an engine of a multi-engine aircraft during fight are provided. One such method comprises: determining a condition to the effect that a flame in the combustion equipment of the second gas turbine engine has been extinguished; responsive to the determination, supplying electrical power from the electrical energy storage system to one or more of the electric machines of the second gas turbine engine and operating said one or more electric machines as motors to limit a reduction in a speed of the one or more spools of the second gas turbine engine following extinguishment of the flame in its combustion equipment; and restarting the second gas turbine engine by relighting the combustion equipment of the second gas turbine engine.

An assembly for an aircraft turbine engine includes a fan drive reduction gear and a lubrication system including: a reduction gear housing; a lubricant tank; a lubricant supply circuit including a feed pump; and a lubricant recovery circuit including a pump for recovering lubricant from the reduction gear housing. The recovery circuit includes a lubricant distributor, including: a lubricant inlet communicating with a lubricant outlet of the housing; an air inlet; and a distributor outlet, the distributor being able to adopt a lubricant recovery configuration and a configuration for retaining the lubricant in the housing.

A multivariable fuel control and estimator (MFCE) of a gas turbine engine for preventing combustor blowout is provided. The MFCE includes a first input port that receives controller requests and provide system usage commands, a second input port that receives measured disturbance values, a third input that receives system and component limits, a fourth input port that receives sensed parameters, a fuel system model of the fuel system of the gas turbine engine and an engine model of the engine system that includes the combustor of the gas turbine engine, a processor that generates a control signal for controlling the fuel valve and generates a control signal for controlling the actuator using the fuel system and engine model based on the controller requests, the measured disturbance values, the system and component limits, and the sensed parameters, and an output port that transmits the control signals to the fuel system.

Methods and systems for controlling a bleed-off valve of a gas turbine engine are described. The method comprises maintaining a first bleed-off valve associated with a first compressor of the gas turbine engine at least partially open upon detection of an unintended engine disturbance causing a drop in pressure of a combustion chamber of the engine; monitoring a rotor acceleration of the first compressor; and controlling closure of the first bleed-off valve when the rotor acceleration of the first compressor reaches a first threshold for a first duration.

A combustion staging system includes a splitting unit receiving a metered fuel flow and controllably splitting the received flow into pilot and mains flows. Pilot and mains fuel manifolds distribute fuel. A cooling flow recirculation line provides a cooling flow to the mains manifold during pilot-only operation, and a return section to collect mains manifold cooling flow. The cooling flow enters a delivery section and exits the return section. A fuel recirculating control valve on the delivery section has an open position so that the cooling flow enters the delivery section during pilot-only operation; a shut off position prevents the cooling flow entering the delivery section through the cooling flow orifice during pilot and mains operation. A supplementary valve bleeds or feeds cooling flow. The mains manifold cooling flow pressure is determined by the cooling flow and pressure raising orifices flow numbers, and a control setting of the supplementary valve.

The method allows to detect flameout in a combustor of a turbine system; it includes the steps of: A) measuring angular acceleration of a shaft of the or each turbine of the turbine system, B) calculating a flameout indicator as a function of the angular acceleration, and C) carrying out a comparison between the flameout indicator and at least one threshold.

A gas turbine engine includes a compressor section, the compressor section including a variable inlet guide vane which is movable between distinct angles to control the airflow approaching the compressor section. A control is programmed to position the vane at startup of the engine to direct airflow across the compressor section. The engine includes a fan for delivering bypass air into a bypass duct positioned outwardly of a core engine including the compressor section. The position of the vane is configured to direct airflow across the compressor section while an aircraft associated with the gas turbine engine is in the air, and to increase a windmilling speed of the compressor section and the turbine rotors. A method and variable inlet vane are also disclosed.

The subject matter of this specification can be embodied in, among other things, a method that includes igniting an igniter stage configured to ignite combustion in a turbine combustor assembly, receiving pressure signals from a pressure sensor configured to sense pressure in the turbine combustor assembly, and controlling operation of the igniter stage based on the received pressure signals.

There is described a method and system for in-flight start of an engine. The method comprises rotating a propeller; generating electrical power at an electric generator embedded inside a propeller hub from rotation of the propeller; transmitting the electrical power from the electric generator to an engine starter mounted on a core of the engine via an electric power link; and driving the engine with the engine starter to a sufficient speed while providing fuel to a combustor to light the engine to achieve self-sustaining operation of the engine.

Systems and methods for conditionally performing engine operational tests for a turbine engine are provided. A system comprising at least one processor can be configured to obtain sensor data associated with at least one sensor for a turbine engine. The sensor data identifies a current fuel flow associated with the turbine engine. The system can determine a predicted fuel flow of the turbine engine based at least in part on the current fuel flow and a fuel flow reduction associated with an engine operational test. The system can compare the predicted fuel flow to at least one threshold. The system can selectively initiate the engine operational test based on comparing the predicted fuel flow to the at least one threshold.