Method and a system for characterizing and counting violations of a threshold by an aircraft engine operating parameter

1. A method of characterizing and counting violations of a threshold by an operating parameter of an aircraft engine of an aircraft, said method comprising:

detecting, by the aircraft, a violation of the threshold by the operating parameter while said aircraft engine is in operation;

on detecting the violation, automatically transmitting from the aircraft to a ground system a warning message about the violation;

on the basis of the warning message, automatically determining a severity level for the violation; and

incrementing a counter representing a number of occasions the operating parameter of the aircraft engine has presented a violation corresponding to the severity level.

2. The method according to claim 1 , wherein the warning message transmitted to the ground system is associated with a flight stage of the aircraft and includes at least one value taken by the operating parameter during the violation and the duration of the violation.

3. The method according to claim 2 , wherein the severity level of the violation is determined, from amongst a plurality of predefined severity levels, on the basis of the at least one value taken by the operating parameter during the violation and of the duration of the violation, as contained in the warning message.

4. The method according to claim 2 , wherein said automatically determining the severity level for the violation includes

selecting a diagram corresponding to the aircraft engine and to the flight stage of the aircraft and associated with the operating parameter, said diagram representing a plurality of geometrical severity zones as a function of values taken by the operating parameter and of a duration for which the operating parameter took said values, each geometrical severity zone corresponding to a distinct severity level; and

identifying on the diagram which severity zone contains a point of coordinates given by the at least one value and the duration contained in the warning message.

5. The method according to claim 1 , wherein the operating parameter is a temperature of a gas exhausted from a combustion chamber of the aircraft engine.

6. A system for characterizing and counting violations of a threshold by an operating parameter of an engine of an aircraft on the basis of at least one warning message about such a violation as transmitted automatically by the aircraft, the system comprising:

a sensor for sensing when an operating parameter violates a threshold; a transmitter for automatically transmitting at least one warning message to a ground based system when the operating parameter violates the threshold; a determining unit located at the ground based system configured to act on a reception of the at least one warning message to determine automatically a severity level for the violation; and

an incrementing unit configured to increment a counter representative of a number of times the operating parameter of the aircraft engine has presented a violation corresponding to the severity level.

7. The system according to claim 6 , wherein the at least one warning message is associated with a flight stage of the aircraft and includes at least a value taken by the operating parameter in the violation and the duration of the violation.

8. The system according to claim 7 , wherein the severity level of the violation is determined, from amongst a plurality of predefined severity levels, on the basis of the value taken by the operating parameter during the violation and of the duration of the violation, as contained in the at least one warning message.

9. The system according to claim 7 , wherein the determining unit includes:

a selection unit configured to select a diagram corresponding to the aircraft engine and to the flight stage of the aircraft, and associated with the operating parameter in violation, said diagram representing a plurality of geometrical severity zones as a function of values taken by the operating parameter and of durations during which the operating parameter takes said values, each geometrical severity zone corresponding to a distinct severity level; and

an identification unit configured to identify on the diagram which severity zone contains a point of coordinates given by the value and the duration contained in the at least one warning message for the operating parameter in violation.

10. The system according to claim 6 , wherein the operating parameter is a temperature of an exhaust gas at an outlet from a combustion chamber of the aircraft engine.

11. The method according to claim 4 , wherein the identifying includes identifying a set of indices i, i=1, . . . ,Q for vertices S i of a polygon Θ(Z) that satisfies the following two conditions:

0<{right arrow over ( S i P )}•{right arrow over ( S i S i+1 )}<∥{right arrow over ( S i S i+1 )}∥ 2   (1)

z ({right arrow over ( PS i )}^{right arrow over ( PS i+1 )})>0  (2)

in a rectangular frame of reference (Oxyz) oriented in a counterclockwise direction, wherein axes (Ox) and (Oy) are defined by axes of the diagram, axis (Oz) is orthogonal to a plane of the diagram, the symbols “•” and “^” designate, respectively, a scalar product and a vector product of two vectors, the notation z({right arrow over (u)}) designates a component of a vector {right arrow over (u)}along the axis (Oz), and the vertices S i and S i+1 are adjacent vertices, numbered in the counterclockwise direction, and

determining whether for at least one index of the set of indices there exists an index such that the triangles PS j S j+1 , PS j+1 S k , and PS k S j are direct triangles, wherein P is the point of coordinates.