Abstract: A fuel control system may include a primary power bank, a secondary power bank, a first electronic control channel electrically connected to the primary power bank, a second electronic control channel electrically connected to the secondary power bank, and a distribution module. The distribution module further may include a first channel electrically connected to the first electronic control channel and a first plurality of electromagnetic fuel nozzles (ECNs) contained within a combustor, a second channel electrically connected to the second electronic control channel and a second plurality of ECNs, and a channel link electrically connecting the first channel and the second channel, wherein the first electronic control channel and the second electronic control channel are not directly electrically connected.

Abstract: In accordance with at least one aspect of this disclosure, a method can include controlling firing of an exciter of an engine with an electronic controller separate from the exciter as a function of at least one excitation command from the electronic controller and at least one feedback signal from the exciter operatively connected to the electronic controller.

Abstract: A cooling system includes a fuel supply system and a cooling fuel path. The fuel supply system includes a boost stage pump and a main stage pump, while the cooling fuel path includes a fuel bleed from an outlet of the boost stage pump, a fuel return to an inlet of the boost stage pump, and a cooler disposed fluidly between the fuel bleed and the fuel return.

Abstract: A method for detecting performance degradation of an AC Nozzle in a gas turbine engine including operating the gas turbine engine under a normal operating condition, maintaining the fuel flow rate at a constant fuel flow rate, determining a delta pressure PDelta-Normal across an N number of Proportional Metering Valves (PMVs) as the gas turbine engine is operating under the normal operating condition, selecting a PMV and an AC Nozzle, controlling the PMV to modify a fuel flow rate to the selected AC Nozzle to cause the gas turbine engine to operate under a modified fuel flow condition, determining a delta pressure PDelta-Modified across the N number of PMVs as the gas turbine engine is operating under the modified operating condition and comparing the delta pressure PDelta-Normal with the delta pressure PDelta-Modified to determine if the selected AC Nozzle is uncalibrated or has failed.

Abstract: An engine ignition system can include a multifunction controller, and an exciter operatively connected to the multifunction controller. The multifunction controller can be configured to control the exciter to output an ignition voltage. The multifunction controller can be configured to perform at least one other engine control function.

Abstract: A fuel system a main manifold with an inlet and a plurality of main manifold branches. Each valve in a plurality of valves is connected in fluid communication with a respective one of the main manifold branches in the plurality of main manifold branches to receive flow from the main manifold. Each secondary manifold in a plurality of secondary manifolds connects a single one of the valves in the plurality of valves to a pair of secondary manifold branches. Each nozzle in a plurality of fuel nozzles includes a first inlet connected in fluid communication to one of the valves through one of the secondary manifold branches, and a second inlet connected in fluid communication to a different one of the valves through a different one of the secondary manifold branches so each of the fuel nozzles has a redundant connection to the main manifold through two of the valves.

Abstract: A method for detecting performance degradation of an AC Nozzle in a gas turbine engine including operating the gas turbine engine under a normal operating condition, maintaining the fuel flow rate at a constant fuel flow rate, determining a delta pressure PDelta-Normal across an N number of Proportional Metering Valves (PMVs) as the gas turbine engine is operating under the normal operating condition, selecting a PMV and an AC Nozzle, controlling the PMV to modify a fuel flow rate to the selected AC Nozzle to cause the gas turbine engine to operate under a modified fuel flow condition, determining a delta pressure PDelta-Modified across the N number of PMVs as the gas turbine engine is operating under the modified operating condition and comparing the delta pressure PDelta-Normal with the delta pressure PDelta-Modified to determine if the selected AC Nozzle is uncalibrated or has failed.

Abstract: A fuel system a main manifold with an inlet and a plurality of main manifold branches. Each valve in a plurality of valves is connected in fluid communication with a respective one of the main manifold branches in the plurality of main manifold branches to receive flow from the main manifold. Each secondary manifold in a plurality of secondary manifolds connects a single one of the valves in the plurality of valves to a pair of secondary manifold branches. Each nozzle in a plurality of fuel nozzles includes a first inlet connected in fluid communication to one of the valves through one of the secondary manifold branches, and a second inlet connected in fluid communication to a different one of the valves through a different one of the secondary manifold branches so each of the fuel nozzles has a redundant connection to the main manifold through two of the valves.

Abstract: In accordance with at least one aspect of this disclosure, a method can include controlling firing of an exciter of an engine with an electronic controller separate from the exciter as a function of at least one excitation command from the electronic controller and at least one feedback signal from the exciter operatively connected to the electronic controller.

Abstract: An engine ignition system can include a multifunction controller, and an exciter operatively connected to the multifunction controller. The multifunction controller can be configured to control the exciter to output an ignition voltage. The multifunction controller can be configured to perform at least one other engine control function.