According to an aspect, a ground-based health test of a fuel pump of a fuel control system of a gas turbine engine is initiated. A starter speed of the gas turbine engine is determined while the ground-based health test is in progress. Fuel flow is initiated from the fuel pump to an ignition system of the gas turbine engine with the starter speed set below a nominal ground-based engine starting speed. A parameter of the gas turbine engine is monitored to verify light-off. A health status of the fuel pump is determined based on the starter speed at which light-off is achieved.

According to an aspect, a ground-based health test of a fuel pump of a fuel control system of a gas turbine engine is initiated. A starter speed of the gas turbine engine is determined while the ground-based health test is in progress. Fuel flow is initiated from the fuel pump to an ignition system of the gas turbine engine with the starter speed set below a nominal ground-based engine starting speed. A parameter of the gas turbine engine is monitored to verify light-off. A health status of the fuel pump is determined based on the starter speed at which light-off is achieved.

A slinger combustor includes; a first compressed air line connected to a compressor and configured to supply compressed air; a first fuel line connected to a fuel storage and configured to supply fuel; a rotation shaft configured to rotate and inject the fuel supplied from the first fuel line; a main combustion chamber configured to receive the fuel injected from the rotation shaft and receive the compressed air from the first compressed air line; and a sub-combustion chamber configured to selectively discharge a flame generated in an inner space of the sub-combustion chamber to the main combustion chamber.

A propulsion system including: a fuel cell assembly having a fuel cell defining an outlet positioned to remove output products from the fuel cell and a fuel cell assembly operating condition; a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order, the combustion section configured to receive a flow of aviation fuel from an aircraft fuel supply and further configured to receive the output products from the fuel cell; and a controller comprising memory and one or more processors, the memory storing instructions that when executed by the one or more processors cause the propulsion system to perform operations including receiving data indicative of a mid-flight flameout within the combustion section; modifying the fuel cell assembly operating condition in response to receiving data indicative of the mid-flight flameout within the combustion section; and initiating a relight of the combustion section.

A propulsion system including: a fuel cell assembly having a fuel cell defining an outlet positioned to remove output products from the fuel cell and a fuel cell assembly operating condition; a turbomachine comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order, the combustion section configured to receive a flow of aviation fuel from an aircraft fuel supply and further configured to receive the output products from the fuel cell; and a controller comprising memory and one or more processors, the memory storing instructions that when executed by the one or more processors cause the propulsion system to perform operations including receiving data indicative of a mid-flight flameout within the combustion section; modifying the fuel cell assembly operating condition in response to receiving data indicative of the mid-flight flameout within the combustion section; and initiating a relight of the combustion section.

An example system includes a first gas-turbine engine configured to propel an aircraft, the first gas-turbine engine comprising: a first air-turbine starter, the first air-turbine starter configured to rotate a spool of the first gas-turbine engine; and a first electric starter, the first electric starter configured to rotate the spool of the first gas-turbine engine; and one or more controllers collectively configured to: cause, during a time period, the first-air turbine starter and the first electric starter to start the first gas-turbine engine while the aircraft is on the ground; measure, during the time period, values of one or more parameters of the first gas-turbine engine; and determine, based on the values of the one or more parameters, whether the first electric starter is available for use in performing mid-air restart of the first gas-turbine engine.

An example system includes a first gas-turbine engine configured to propel an aircraft, the first gas-turbine engine comprising: a first air-turbine starter, the first air-turbine starter configured to rotate a spool of the first gas-turbine engine; and a first electric starter, the first electric starter configured to rotate the spool of the first gas-turbine engine; and one or more controllers collectively configured to: cause, during a time period, the first-air turbine starter and the first electric starter to start the first gas-turbine engine while the aircraft is on the ground; measure, during the time period, values of one or more parameters of the first gas-turbine engine; and determine, based on the values of the one or more parameters, whether the first electric starter is available for use in performing mid-air restart of the first gas-turbine engine.

A system includes a gas turbine engine configured to provide propulsion to an aircraft and a starter system configured to start the gas turbine engine. The starter system comprises a motor controller and a closed-loop cooling system configured to cool the motor controller during an emergency in-flight restart operation of the gas turbine engine. The closed-loop cooling system includes a cooling fluid reservoir containing cooling fluid. The cooling fluid is configured to receive thermal energy from the motor controller during the emergency in-flight restart operation of the gas turbine engine.

A system includes a gas turbine engine configured to provide propulsion to an aircraft and a starter system configured to start the gas turbine engine. The starter system comprises a motor controller and a closed-loop cooling system configured to cool the motor controller during an emergency in-flight restart operation of the gas turbine engine. The closed-loop cooling system includes a cooling fluid reservoir containing cooling fluid. The cooling fluid is configured to receive thermal energy from the motor controller during the emergency in-flight restart operation of the gas turbine engine.

A turbine system includes a compressor system compressing a fluid, a combustor system fluidly coupled to the compressor to combust a fuel mixed with the fluid to produce a combusted fluid, a gas turbine system fluidly coupled to the combustor to rotate a gas turbine shaft based on the combusted fluid, a power turbine system fluidly coupled to the gas turbine to rotate a power turbine shaft based on the combusted fluid existing the gas turbine, the shaft mechanically coupled to a clutch system, a clutch system mechanically coupled to a generator shaft, and an electric generator having the generator shaft to produce electricity based on rotations of the generator shaft. The turbine system includes a controller operatively coupled to the clutch system to restart production of the electricity via the clutch system.