A control system for an in-flight engine restart system of a rotorcraft includes an engine control unit that controls and detects status of an engine. The control system also includes a flight control computer that communicates with the engine control unit, an engine operation control system, and a pilot interface including pilot controls. The engine operation control system includes a processor that initiates a health check of the in-flight engine restart system to determine an in-flight engine restart system status. The engine operation control system processes engine mode of operation commands to establish an engine mode of operation, and delivers commands to aspects of the in-flight engine restart system including the engine control unit based on processing of the engine mode of operation commands. The engine operation control system reports the in-flight engine restart system status and results of the engine mode of operation commands to the flight control computer.

A control system for an in-flight engine restart system of a rotorcraft includes an engine control unit that controls and detects status of an engine. The control system also includes a flight control computer that communicates with the engine control unit, an engine operation control system, and a pilot interface including pilot controls. The engine operation control system includes a processor that initiates a health check of the in-flight engine restart system to determine an in-flight engine restart system status. The engine operation control system processes engine mode of operation commands to establish an engine mode of operation, and delivers commands to aspects of the in-flight engine restart system including the engine control unit based on processing of the engine mode of operation commands. The engine operation control system reports the in-flight engine restart system status and results of the engine mode of operation commands to the flight control computer.

Methods and systems for reigniting an engine of an aircraft are described. An engine flameout event is detected during flight. Responsive to detecting the engine flameout event, an engine speed and a commanded engine operating state are monitored. The engine speed is compared to a predetermined threshold. A determination is made regarding whether the commanded engine operating state corresponds to an engine on state. When the commanded engine operating state corresponds to the engine on state, and when the engine speed is below the predetermined threshold, a predetermined ignition sequence for the engine is initiated.

Methods and systems for reigniting an engine of an aircraft are described. An engine flameout event is detected during flight. Responsive to detecting the engine flameout event, an engine speed and a commanded engine operating state are monitored. The engine speed is compared to a predetermined threshold. A determination is made regarding whether the commanded engine operating state corresponds to an engine on state. When the commanded engine operating state corresponds to the engine on state, and when the engine speed is below the predetermined threshold, a predetermined ignition sequence for the engine is initiated.

An architecture of a propulsion system of a multi-engine helicopter is disclosed, comprising turboshaft engines that are connected to a power transmission gearbox. It comprises: a hybrid turboshaft engine that is capable of operating in at least one standby mode during a stable flight of the helicopter; a pack for quickly restarting said hybrid turboshaft engine in order to bring said engine out of said standby mode and to reach a nominal operating mode; an auxiliary power unit that is connected to said electrotechnical restart pack by means of a first AC/DC converter and is capable of providing said restart pack, on demand, with power required for bringing said hybrid turboshaft engine out of said standby mode.

An architecture of a propulsion system of a multi-engine helicopter is disclosed, comprising turboshaft engines that are connected to a power transmission gearbox. It comprises: a hybrid turboshaft engine that is capable of operating in at least one standby mode during a stable flight of the helicopter; a pack for quickly restarting said hybrid turboshaft engine in order to bring said engine out of said standby mode and to reach a nominal operating mode; an auxiliary power unit that is connected to said electrotechnical restart pack by means of a first AC/DC converter and is capable of providing said restart pack, on demand, with power required for bringing said hybrid turboshaft engine out of said standby mode.

A fuel control system according to an exemplary aspect of the present disclosure includes, among other things, a fuel delivery valve selectively moveable to a closed position to shut off a flow of fuel to a downstream location. The system further includes a windmill bypass valve, and a shutoff pressure line between the windmill bypass valve and the fuel delivery valve. The windmill bypass valve is selectively operable to direct fuel to the shutoff pressure line to assist the movement of the fuel delivery valve to the closed position. A method is also disclosed.

A fuel control system according to an exemplary aspect of the present disclosure includes, among other things, a fuel delivery valve selectively moveable to a closed position to shut off a flow of fuel to a downstream location. The system further includes a windmill bypass valve, and a shutoff pressure line between the windmill bypass valve and the fuel delivery valve. The windmill bypass valve is selectively operable to direct fuel to the shutoff pressure line to assist the movement of the fuel delivery valve to the closed position. A method is also disclosed.

A hybrid-electric propulsion system for an aircraft includes a propulsor and a turbomachine. The turbomachine includes a high pressure turbine drivingly coupled to a high pressure compressor through a high pressure spool. The hybrid electric propulsion system further includes an electrical system including a first electric machine, a second electric machine, and an electric energy storage unit electrically connectable to the first and second electric machines. The first electric machine is coupled to the high pressure spool of the turbomachine and the second electric machine is coupled to the propulsor for driving the propulsor to provide a propulsive benefit for the aircraft. The hybrid electric propulsion system also includes a controller configured to provide electrical power from an electric power source to the first electric machine to drive the first electric machine to start, or assist with starting, the turbomachine.

A hybrid-electric propulsion system for an aircraft includes a propulsor and a turbomachine. The turbomachine includes a high pressure turbine drivingly coupled to a high pressure compressor through a high pressure spool. The hybrid electric propulsion system further includes an electrical system including a first electric machine, a second electric machine, and an electric energy storage unit electrically connectable to the first and second electric machines. The first electric machine is coupled to the high pressure spool of the turbomachine and the second electric machine is coupled to the propulsor for driving the propulsor to provide a propulsive benefit for the aircraft. The hybrid electric propulsion system also includes a controller configured to provide electrical power from an electric power source to the first electric machine to drive the first electric machine to start, or assist with starting, the turbomachine.