Methods and systems for controlling thrust produced by a plurality of engines on an aircraft for assisting with certain flight conditions

1. A method of controlling thrust produced by a plurality of engines on an aircraft for assisting with nose-down recovery of the aircraft, the method comprising:

selecting a maximum value of an aircraft parameter to be a value greater than a value achievable by the aircraft in flight with one engine failed of the plurality of engines;

measuring a value of the aircraft parameter while the aircraft is in flight;

based on a comparison of the maximum value and the measured value, determining that the measured value exceeds the maximum value;

setting a maximum amount by which a thrust produced by each of the engines of the plurality of engines may be reduced to preserve a required climb capability; and

reducing the thrust produced by each of the engines of the plurality of engines within the maximum amount to bring the measured value of the aircraft parameter below the maximum value of the aircraft parameter, only when all engines of the plurality of engines are operating.

2. The method of claim 1 , wherein selecting the maximum value of the aircraft parameter comprises selecting a maximum value of a longitudinal acceleration (N x ) of the aircraft.

3. The method of claim 1 , wherein selecting the maximum value of the aircraft parameter comprises selecting a maximum value of an angle of attack (AoA) of the aircraft.

4. The method of claim 1 , wherein selecting the maximum value of the aircraft parameter comprises selecting a maximum value of a flight path angle of the aircraft.

5. The method of claim 1 , wherein selecting the maximum value of the aircraft parameter comprises selecting a maximum value of a pitch angle of the aircraft.

6. The method of claim 1 , wherein selecting the maximum value of the aircraft parameter comprises:

selecting the maximum value to be at a limit that provides recovery capability of the aircraft at an angle of attack (AOA) above a threshold.

7. The method of claim 1 , wherein selecting the maximum value of the aircraft parameter comprises:

selecting the maximum value of the aircraft parameter based on a weight of the aircraft.

8. The method of claim 1 , wherein measuring the value of the aircraft parameter while the aircraft is in flight comprises:

measuring a longitudinal acceleration, wherein the longitudinal acceleration is a measure of excess thrust relative to drag and weight of the aircraft.

9. The method of claim 1 , wherein reducing the thrust produced by each of the engines comprises:

reducing the thrust by an amount proportionate to an amount that the measured value exceeds the maximum value.

10. The method of claim 1 , further comprising:

determining that a nose-down recovery condition exists; and

based on the determination of the nose-down recovery condition,

measuring the value of the aircraft parameter while the aircraft is in flight; and

reducing the thrust produced by each of the engines to bring the measured value of the aircraft parameter below the maximum value of the aircraft parameter.

11. The method of claim 1 , wherein reducing the thrust produced by each of the engines comprises reducing the thrust by a first amount, and the method further comprises:

after reducing the thrust, measuring a second value of the aircraft parameter; and

based on the second measured value exceeding the maximum value, reducing the thrust produced by each of the engines by a second amount that is larger than the first amount.

12. The method of claim 1 , further comprising:

iteratively measuring the value of the aircraft parameter and reducing the thrust produced by each of the engines until the measured value of the aircraft parameter is below the maximum value of the aircraft parameter.

13. A non-transitory computer readable medium having stored thereon instructions, that when executed by one or more processors of a computing device, cause the computing device to perform functions comprising:

selecting a maximum value of an aircraft parameter to be a value greater than a value achievable by the aircraft in flight with one engine failed of the plurality of engines;

measuring a value of the aircraft parameter while the aircraft is in flight;

based on a comparison of the maximum value and the measured value, determining that the measured value exceeds the maximum value;

setting a maximum amount by which a thrust produced by each of the engines of the plurality of engines may be reduced to preserve a required climb capability; and

reducing the thrust produced by each of the engines of the plurality of engines within the maximum amount to bring the measured value of the aircraft parameter below the maximum value of the aircraft parameter, only when all engines of the plurality of engines are operating.

14. The non-transitory computer readable medium of claim 13 , wherein measuring the value of the aircraft parameter while the aircraft is in flight comprises:

measuring a longitudinal acceleration, wherein the longitudinal acceleration is a measure of excess thrust relative to drag and weight of the aircraft.

15. The non-transitory computer readable medium of claim 13 , wherein reducing the thrust produced by each of the engines comprises:

reducing the thrust by an amount proportionate to an amount that the measured value exceeds the maximum value.

16. A system comprising:

a flight control computing device having a processor and memory storing instructions executable by the processor to:

select a maximum value of an aircraft parameter of an aircraft to be a value greater than a value achievable by the aircraft in flight with one engine failed of the plurality of engines;

receive a measurement of a value of the aircraft parameter while the aircraft is in flight;

based on a comparison of the maximum value and the measurement, determine that the measurement exceeds the maximum value;

set a maximum amount by which a thrust produced by each engine of a plurality of engines of the aircraft may be reduced to preserve a required climb capability; and

send a signal indicating to reduce the thrust produced by each engine of a plurality of engines of the aircraft within the maximum amount to bring the measurement below the maximum value of the aircraft parameter, only when all engines of the plurality of engines are operating; and

a plurality of propulsion control computing devices coupled to the plurality of engines of the aircraft, wherein a respective propulsion control computing device is coupled to a respective engine, and wherein each propulsion control computing device has a processor and memory storing instructions executable by the processor to receive the signal from the flight control computing device and to control thrust produced by the respective engine of the plurality of engines.

17. The system of claim 16 , wherein the plurality of propulsion control computing devices control thrust produced by each engine of the plurality of engines independently of each other.

18. The system of claim 16 , further comprising:

an inertial reference unit (IRU) to measure the value of the aircraft parameter while the aircraft is in flight, and to output the measurement of the value of the aircraft parameter to the flight control computing device.

19. The method of claim 1 , further comprising:

prohibiting thrust reduction if less than a threshold number of the plurality of engines are operating on the aircraft.

20. The non-transitory computer readable medium of claim 13 , wherein the functions further comprise:

iteratively measuring the value of the aircraft parameter and reducing the thrust produced by each of the engines until the measured value of the aircraft parameter is below the maximum value of the aircraft parameter.