Systems and methods for determining gas turbine engine operating margins

1 . A system for determining an engine operating margin for an engine parameter of an aircraft, the system comprising:

a gas turbine engine system, the gas turbine engine system comprising a gas turbine engine, an engine control system, and one or more sensors,

the gas turbine engine comprising a core flowpath formed by an air inlet, a first rotational assembly, a second rotational assembly, and an exhaust section; and

the engine control system including a processor in communication with a non-transitory memory storing instructions, the engine control system in communication with the one or more sensors;

wherein the instructions when executed by the processor, cause the processor to:

obtain a current engine installation configuration for the gas turbine engine stored in the memory;

determine an expected normalized value of the engine parameter for an uninstalled gas turbine engine based on the current engine installation configuration and one or more of a normalized engine power (SHPN) of the gas turbine engine, an airspeed, or an altitude;

determine a scaling factor based on one or more of SHPN, altitude, current International Standard Atmosphere (ISA) deviation, or the current engine installation configuration;

apply the scaling factor to the expected normalized value of the engine parameter;

determine a fully deteriorated engine (FDE) value of the engine parameter using the normalized value of the engine parameter;

determine a current value of the engine parameter for the gas turbine engine from the one or more sensors;

determine the engine operating margin for the engine parameter based on the FDE value of the engine parameter and the current value of the engine parameter,

display a live indication of the engine operating margin for the engine parameter on a display of the aircraft; and

identify the presence or absence of a need for gas turbine engine maintenance by comparing the engine operating margin to a threshold margin value.

2 . The system of claim 1 , wherein the engine parameter is an indicated turbine temperature (ITT).

3 . The system of claim 1 , wherein the engine parameter is a compressor speed.

4 . The system of claim 1 , wherein the instructions, when executed by the processor, further cause the processor to:

calculate a current engine inlet pressure loss using an engine inlet pressure and an outside ambient pressure;

compare the current engine inlet pressure loss to an expected nominal engine inlet pressure loss for the current engine installation configuration to determine an inlet pressure loss correction factor; and

apply the inlet pressure loss correction factor to the normalized engine power (SHPN).

5 . A method for determining an engine operating margin for an engine parameter of a gas turbine engine system for an aircraft, the gas turbine engine system including a gas turbine engine, an engine control system, and one or more sensors, the engine control system including a processor in communication with a non-transitory memory storing instructions, and the engine control system in communication with the one or more sensors, the method comprising:

identifying a current engine installation configuration for the gas turbine engine stored in the non-transitory memory of the engine control system;

determining an expected normalized value of the engine parameter for an uninstalled gas turbine engine based on the current engine installation configuration and one or more of a normalized engine power (SHPN) of the gas turbine engine, an airspeed, or an altitude;

determining a scaling factor based on one or more of SHPN, altitude, current International Standard Atmosphere (ISA) deviation, or the current engine installation configuration;

applying the scaling factor to the expected normalized value of the engine parameter;

determining a fully deteriorated engine (FDE) value of the engine parameter using the normalized value of the engine parameter;

determining a current value of the engine parameter for the gas turbine engine with the one or more sensors;

determining the engine operating margin for the engine parameter based on the FDE value of the engine parameter and the current value of the engine parameter, and

displaying a live indication of the engine operating margin for the engine parameter on a display of the aircraft;

wherein the displayed engine operating margin signals an operator to perform maintenance on the gas turbine engine when the engine operating margin decreases below a threshold margin value.

6 . The method of claim 5 , wherein the engine parameter is an indicated turbine temperature (ITT).

7 . The method of claim 5 , wherein the engine parameter is a high-pressure compressor speed (NH).

8 . The method of claim 5 , further comprising:

determining an accessory extraction load for the gas turbine engine;

determining an accessory extraction load correction factor using the normalized engine power (SHPN), the altitude, and the accessory extraction load; and

adding the accessory extraction load correction factor to the expected normalized value of the engine parameter.

9 . The method of claim 5 , wherein the step of determining the current value of the engine parameter for the gas turbine engine includes measuring the engine parameter using one or more sensors of the gas turbine engine.

10 . The method of claim 5 , wherein the step of determining the current value of the engine parameter includes estimating the current value of the engine parameter using a computer-implemented model.

11 . The method of claim 5 , wherein the step of determining the FDE value of the engine parameter includes determining a deterioration correction factor for the FDE value, the deterioration correction factor based on one or more operational characteristics of a compressor of the gas turbine engine.

12 . A gas turbine engine for an aircraft, the gas turbine engine comprising:

an air inlet;

a first rotational assembly including a first shaft, a bladed first compressor rotor, and a bladed first turbine rotor, the first shaft interconnecting the bladed first compressor rotor and the bladed first turbine rotor;

a second rotational assembly include a second shaft, a bladed second compressor rotor, and a bladed second turbine rotor, the second shaft interconnecting the bladed second compressor rotor and the bladed second turbine rotor;

an exhaust section,

wherein the air inlet, the first rotational assembly, the second rotational assembly, and the exhaust section form a core flow path of the gas turbine engine;

one or more sensors distributed throughout the gas turbine engine; and

an engine control system, the engine control system including a processor in communication with a non-transitory memory storing instructions, and the engine control system in communication with the one or more sensors distributed throughout the gas turbine engine;

wherein the instructions when executed by the processor, cause the processor to:

obtain a current engine installation configuration for the gas turbine engine;

determine an expected normalized value of an engine parameter for an uninstalled engine based on one or more of a normalized engine power (SHPN) of the gas turbine engine, an airspeed, or an altitude;

determine a scaling factor based on one or more of SHPN, altitude, current International Standard Atmosphere (ISA) deviation, or the current engine installation configuration;

apply the scaling factor to the expected normalized value of the engine parameter;

determine a fully deteriorated engine (FDE) value of the engine parameter of the gas turbine engine using the normalized value of the engine parameter;

determine a current value of the engine parameter for the gas turbine engine using the one or more sensors;

determine an engine operating margin for the engine parameter based on the FDE value of the engine parameter and the current value of the engine parameter, and

display a live indication of the engine operating margin for the engine parameter on a display of the aircraft;

wherein the displayed engine operating margin signals an operator to perform maintenance on the gas turbine engine when the engine operating margin decreases below a threshold margin value.

13 . The gas turbine engine of claim 12 , wherein the normalized value of an engine parameter is determined for the current engine installation configuration.

14 . The gas turbine engine of claim 13 , wherein the current engine installation configuration includes an air inlet configuration.

15 . The gas turbine engine of claim 13 , wherein the current engine installation configuration includes an exhaust section configuration.

16 . The gas turbine engine of claim 12 , wherein the engine control system includes a plurality of sensors.

17 . The gas turbine engine of claim 16 , wherein the plurality of sensors includes at least a speed sensor for the first rotational assembly and a torque sensor for the first rotational assembly, and wherein the step of determining the normalized value of the engine parameter for the uninstalled engine based on the normalized engine power (SHPN) of the gas turbine engine includes determining the normalized engine power (SHPN) using a rotational speed measured by the speed sensor and a torque measured by the torque sensor.