Systems and Methods are described for testing engine performance in-flight in an aircraft having a first engine and a second engine. The method comprises operating the first engine at a first power level in an output speed governing mode, operating the second engine at a second power level greater than the first power level in a core speed governing mode concurrently with the first engine operating at the first power level in the output speed governing mode, and performing an engine performance test on the second engine while the second engine is at the second power level in the core speed governing mode.

In an embodiment, a rotorcraft includes: a plurality of engines; a flight control computer connected to the plurality of engines, the flight control computer being configured to: receive an operating parameter of a first engine of the plurality of engines; determine an engine output ramping rate for the first engine according to a difference between the operating parameter of the first engine and a nominal limit of the first engine; and increase the output of the first engine in response to detecting an outage of another engine of the plurality of engines, the output of the first engine being increased according to the engine output ramping rate.

An aircraft including lean-burn gas turbine engines operating in pilot-plus-mains mode with a given initial fuel flow W.sub.0, a method of controlling the optical depth of contrails produced by a first group of engines includes the steps of (i) reducing fuel flow to each engine in the first group to change the operation of each engine from pilot-plus-mains mode to pilot-only mode, and (ii) adjusting fuel flow to one or more engines in a second group of engines such that the total fuel flow to engines of the second group is increased, all engines of the second group remaining in pilot-plus-mains mode, and wherein the set of lean-burn engines consists of the first and second groups. Depending on atmospheric conditions, the average optical depth of contrails produced by the engines may be enhanced or reduced compared to when all engines operate in pilot-plus-mains mode with a fuel flow W.sub.0.

An engine system for an aircraft includes a first gas turbine engine, a first core turning system, a second gas turbine engine, and a second core turning system. The engine system also includes a controller operable to shutdown the first gas turbine engine responsive to determining that the aircraft has landed and operate in the second gas turbine engine in a taxi mode while using the first core turning system to cool the first gas turbine engine. The controller is further operable to shutdown the second gas turbine engine and disable the first core turning system based on a power-down condition, restart the first gas turbine engine and use the second core turning system to cool the second gas turbine engine based on a restart condition, and complete cooling of the second gas turbine prior to restarting the second gas turbine engine.

Vehicle propulsion control systems, vehicles including the same, and associated methods. A method of regulating the operation of a plurality of engines of a vehicle includes, for each of the plurality of engines, receiving engine status information, assigning an engine health score, and assigning an engine status identifier. The method further includes comparing the operational fitness of two or more engines and modulating an operational configuration of one or more engines. In examples, a vehicle propulsion control system for controlling the operation of a plurality of engines of a vehicle includes a propulsion executive controller (PEC) and a plurality of electronic engine controllers (EECs) that control the operation of respective engines. The PEC is configured to generate and transmit an engine action signal for controlling the operation of the one or more respective engines. In some examples, an aircraft includes a plurality of engines and the vehicle propulsion control system.

A multi-engine aircraft includes a first engine drivingly engaged to a common rotatable load and a second engine drivingly engaged to the common rotatable load, the second engine having a bleed air system and a control system in communication with a compressed air switching system. The control system controls operation of the second engine and/or the compressed air switching system. The compressed air switching system includes a switching valve that is displaceable between at least a first position and a second position, the first position interconnecting a lower pressure inlet and a switch outlet, and the second position interconnecting a high pressure inlet and the switch outlet. The switch outlet is in communication with the bleed air system of the second engine. The control system actuates the switching valve to switch between the first and second positions.

Methods and systems for operating an aircraft having two or more engines are described. The method comprises operating the two or more engines of the aircraft in an asymmetric operating regime, wherein a first of the engines is in an active mode to provide motive power to the aircraft and a second of the engines is in a standby mode to provide substantially no motive power to the aircraft, receiving a request to exit the asymmetric operating regime, the request having at least one parameter associated therewith, selecting one of a plurality of available exit protocols as a function of the at least one parameter, and applying the exit protocol by commanding the engines accordingly.

Methods for monitoring engine health of an aircraft having a first engine and a second engine are provided. In one example, the method includes obtaining a first turbine gas temperature of the first engine and a second engine turbine gas temperature of the second engine from a first flight. The first turbine gas temperature and the second turbine gas temperature are related to each other to define a first value. The first value is compared to a data set for monitoring the engine health.

An aspect includes a method for motoring control for multiple engines of an aircraft is provided. A controller can determine a motoring time of a first engine starting system to cool a first engine. The controller can compare the motoring time of the first engine starting system with a motoring time of one or more other engine starting systems of one or more other engines of the aircraft. The motoring time of the first engine starting system can be controlled relative to a tolerance of the motoring time of the one or more other engine starting systems by adjusting the motoring time of the first engine starting system relative to the one or more other engine starting systems in a motoring sequence based on comparing the motoring time of the first engine starting system with the motoring time of the one or more other engine starting systems.

The present disclosure relates to an architecture of a propulsion system of a multi-engine helicopter comprising turboshaft engines connected to a power transmission gearbox, characterized in that it comprises: at least one hybrid turboshaft engine capable of operating in at least one standby mode during a stable cruise flight of the helicopter; at least two systems for controlling each hybrid turboshaft engine, each system comprising an electric machine connected to the hybrid turboshaft engine and suitable for rotating the gas generator thereof, and at least one source of electrical power for the electric machine, each reactivation system being configured such that it can drive the turboshaft engine in at least one operating mode among a plurality of predetermined modes.