A propulsion system is disclosed comprising a gas turbine engine and an acceleration schedule which determines the rate of acceleration of the gas turbine engine from an idle condition in response to a demand for increased thrust off-idle. The acceleration schedule determines the rate of acceleration in dependence upon the value of an engine parameter of the engine the value of which is substantially unaltered by variation in the magnitude of an electrical load drawn from the engine while it is operating in the idle condition.

An assembly for an aircraft propulsion system includes an engine, a rotation speed sensor, and a controller. The engine includes a rotational assembly. The rotational assembly includes a bladed turbine rotor and a shaft configured for rotation about a rotational axis. The rotation speed sensor is disposed at the rotational assembly. The rotation speed sensor is configured to measure a rotation speed of the rotational assembly. The controller is configured to monitor a rotational parameter of the rotational assembly while the rotational assembly is rotating. The rotational parameter is determined using the measured rotation speed from the rotation speed sensor. The controller is further configured to cause the processor to identify a presence or an absence of a rubbing condition for the rotational assembly by comparing the rotational parameter to an identification threshold for the rotational parameter. The presence of the rubbing condition is identified where the rotational parameter exceeds the identification threshold.

A method for operating a gas turbine engine having a starter-electric generator driven by one of a plurality of shafts of the gas turbine engine is provided. The method includes determining a desired amount of thrust to be produced by the gas turbine engine, as well as a desired amount of electrical power to be drawn from the starter-electric generator of the gas turbine engine. The method operates the gas turbine engine to produce the desired amount of thrust, while drawing less than the desired amount of electrical power from the starter-electric generator. Drawing less than the desired amount of electrical power from the starter-electric generator allows for the desired amount of thrust production, allows for the desired amount of thrust production more quickly, or allows for maintenance of a stall margin for any purpose (such as to increase an efficiency of the engine or to allow for certain engine designs).

A gas turbine engine acceleration control system includes a fuel system to output an amount of fuel and a controller in signal communication with the fuel system. The controller determines a real-time ratio between a real-time fuel flow and a real-time pressure of a gas turbine engine, to determine a real-time acceleration value of the gas turbine engine based on a real-time rotational speed of the gas turbine engine, and to generate a first fuel command signal that reduces a first error between the real-time ratio and a ratio reference value, and a second fuel command signal that reduces a second error between a real-time acceleration value and an acceleration reference value. The controller generates a blended fuel delivery command signal based on the first and second fuel command signals, and controls the fuel system to change the fuel flow using the blended fuel delivery command signal.

A method for controlling a gas turbine engine including estimating a temperature gradient between first and second portions of a spool, comparing the estimated temperature gradient with a temperature gradient threshold, if the temperature gradient is less than the threshold, driving a drive shaft in rotation at a rotational speed varying over time according to a first profile of rotational speed variation, and if the temperature gradient is greater than the threshold, controlling the electric motor to drive the drive shaft in rotation such as to vary the rotational speed of the drive-shaft according to a second profile of rotational speed variation over time so that, when the rotational speed lies within a critical interval of rotational speeds, acceleration of rotation of the drive shaft is greater than acceleration of rotation of the drive-shaft according to the first profile of rotational speed variation, within the same critical interval.

A method includes sending a first control signal, wherein the first control signal causes a turbine engine of a plurality of turbine engines of an aircraft to initiate an entry into an asymmetric operating regime. The method further includes receiving, a control input for an exit from the asymmetric operating regime, determining, a progression state of the turbine engine into the asymmetric operating regime, and sending a second control signal for accelerating the turbine engine to a high-power operating regime, wherein the second control signal specifies a acceleration rate based on the progression state of the turbine engine into the asymmetric operating regime.