Method and device for limiting the roll command of an aircraft as a function of a thrust asymmetry

1. A method for automatically managing roll piloting of a multi-engine aircraft, according to which method a roll command is generated, comprising:

a) measuring on each of the engines of the aircraft, a value representative of a thrust of each engine;

b) converting each of the measured values into an effective thrust value for each engine;

c) calculating, from each of the effective thrust values, an overall thrust moment about a vertical axis of the aircraft, said overall thrust moment representing thrust asymmetry of the aircraft;

d) determining a maximum roll rate from the overall thrust moment, accounting for load level of a rear structure of the aircraft, in which the load level is based on roll rate and the thrust asymmetry, wherein the maximum roll rate corresponds to a maximum load level for the thrust asymmetry; and

e) limiting said roll command using said maximum roll rate.

2. The method as claimed in claim 1 , further comprising f) applying said roll command to at least one roll control system of the aircraft.

3. The method as claimed in claim 1 , wherein, in step a), for each engine, a value of a speed of the low pressure stage of said engine is measured.

4. The method as claimed in claim 1 , wherein, in step a), for each engine, a position of a corresponding control lever is measured.

5. The method as claimed in claim 1 , wherein, in step a) transmitted fault information relating to said engines of the aircraft is received.

6. A method for automatically managing roll piloting of a multi-engine aircraft, according to which method a roll command is generated, comprising:

a) measuring on each of the engines of the aircraft, a value representative of a thrust of each engine;

b) converting each of the measured values into an effective thrust value for each engine;

c) calculating, from each of the effective thrust values, an overall thrust moment about a vertical axis of the aircraft, said overall thrust moment representing thrust asymmetry of the aircraft;

d) determining a maximum roll rate from the overall thrust moment, accounting for load level of a rear structure of the aircraft, in which the load level is based on roll rate and the thrust asymmetry, wherein the maximum roll rate corresponds to a maximum load level for the thrust asymmetry; and

e) limiting said roll command using said maximum roll rate, wherein

for an aircraft with electric flight controls, said roll command is expressed in a form of a roll rate and wherein, in step e), the roll rate is limited directly to said maximum roll rate.

7. A method for automatically managing roll piloting of a multi-engine aircraft, according to which method a roll command is generated, comprising:

a) measuring on each of the engines of the aircraft, a value representative of a thrust of each engine;

b) converting each of the measured values into an effective thrust value for each engine;

c) calculating, from each of the effective thrust values, an overall thrust moment about a vertical axis of the aircraft, said overall thrust moment representing thrust asymmetry of the aircraft;

d) determining a maximum roll rate from the overall thrust moment, accounting for load level of a rear structure of the aircraft, in which the load level is based on roll rate and the thrust asymmetry, wherein the maximum roll rate corresponds to a maximum load level for the thrust asymmetry; and

e) limiting said roll command using said maximum roll rate, wherein

for an aircraft with manual flight controls, calculating, in step e), a limit deflection value δlmax of banking control surfaces is configured to act on the roll of the aircraft, using the following expression: δlmax=(K/V).pmax

in which:

K is a predetermined gain;

V is an aerodynamic speed of the aircraft; and

pmax is said maximum roll rate determined in step d), said limit deflection value calculated being applied to adjustable stops of said banking control surfaces.

8. A device for management of roll piloting of a multi-engine aircraft upon generating a roll command, comprising:

control system that automatically measures , on each engine of the aircraft, a value representative of a thrust of each engine;

flight control computer that converts each of said measured values into an effective thrust value;

thrust moment calculating unit that automatically calculates, from the effective thrust values obtained for each engine, an overall thrust moment about a vertical axis of the aircraft, said overall thrust moment representing a thrust asymmetry of the aircraft;

maximum roll rate unit that automatically determines a maximum roll rate from the overall thrust moment, accounting for load level of a rear structure of the aircraft, in which the load level is based on roll rate and the thrust asymmetry, wherein the maximum roll rate, corresponds to a maximum load level for the thrust asymmetry; and

maximum roll rate unit that automatically limits said roll command using said maximum roll rate.

9. The device as claimed in claim 8 , further comprising at least one roll control system of the aircraft.

10. An aircraft, further comprising the device of claim 8 .