Method for detecting damage to a rotor of an aircraft

1. A method for detecting damages to a rotor of an aircraft, wherein the aircraft comprises actuators for active vibration reduction, the method comprising the following steps:

determining actuator variables in a reference flight of the aircraft, wherein the actuator variables determined in the reference flight of the aircraft are used for active vibration reduction with the actuators;

plotting the actuator variables of respective data range tiles determined in the reference flight of the aircraft in first coordinates of a coordinate system, wherein the coordinate system contains numerous closed and non-overlapping data range tiles, wherein the coordinates are also assigned to respective data range tiles, and wherein numerous coordinates can be plotted in a data range tile;

obtaining the number of actuator variables in the reference flight of the aircraft that are located in each data range tile;

eliminating the data range tiles that have a number of actuator variables lying below a limit value for this in the reference flight of the aircraft to create a reference flight signature;

determining actuator variables for a flight-specific signature, wherein the actuator variables determined in the flight of the aircraft are used for vibration reduction with the actuators;

plotting the actuator variables determined in the flight of the aircraft in second coordinates of the coordinate system, wherein the coordinate system contains numerous data range tiles, wherein the second coordinates are also assigned to data range tiles, wherein numerous coordinates can be plotted in a data range tile, and wherein the data range tiles of the flight-specific signature are identical to the data range tiles of the reference flight signature;

obtaining the number of actuator variables in the flight of the aircraft that are located in each data range tile;

eliminating the data range tiles that have a number of actuator variables in the flight of the aircraft that lies below a limit value for this to create the flight-specific signature; and

comparing the respective data range tiles from the flight-specific signature and the reference flight signature, wherein, if a limit value for the number of data range tiles deviating between the flight-specific signature and the reference flight signature is exceeded, a warning signal regarding a damage detection is issued.

2. The method according to claim 1 , wherein the respective actuator variables are plotted in polar coordinates of a polar coordinate system.

3. The method according to claim 2 , wherein additional data range tiles for all angular coordinates from a pole of the polar coordinate system to a limit value radial coordinate are augmented prior to plotting the reference flight signature.

4. The method according to claim 1 , wherein at least the comparison of the flight-specific signature with the reference flight signature is carried out during the flight of the aircraft.

5. The method according to claim 1 , wherein at least the comparison of the flight-specific signature with the reference signature is carried out after the flight of the aircraft.

6. The method according to claim 1 , wherein a minimum number of actuator variables is first obtained in the flight of the aircraft, before the comparison of the flight-specific signature with the reference flight signature.

7. The method according to claim 1 , wherein a difference between the flight-specific signature and the reference flight signature is obtained in order to obtain a difference signature, wherein the difference signature is compared with numerous damage signatures stored in a data base in order to identify a specific damage.

8. The method according to claim 7 , wherein the damage signatures stored in the data base have been determined in actual tests and/or computer simulations.

9. The method according to claim 1 , wherein an adjustable trim flap is used as an actuator for active vibration reduction.

10. The method according to claim 1 , wherein an adjustable push rod is used as an actuator for active vibration reduction.

11. The method according to claim 1 , wherein the reference flight signature is created from a minimum number of reference flights of the aircraft.

12. The method according to claim 1 , wherein the warning signal is issued if a gradient for the number of data range tiles deviating between the flight-specific signature and the reference flight signature exceeds a limit value.

13. The method according to claim 1 , wherein the previously determined reference flight signature can be replaced or expanded by data from further reference flights.