Patent ID: 6921248

Claim:
A real-time process for controlling the torsional stability of a drivetrain of a helicopter, said helicopter comprising at least a power train including the drivetrain, with a main rotor, an anti-torque rotor as well as gearboxes and associated shafts, and an engine with a free turbine which provides motive energy for driving said main rotor and tail rotor of the drivetrain, the helicopter comprising a system to regulate the speed of the turbine engine and comprising at least; a first means for acting on maid speed as a function of operating commands; a second means fox measuring a speed NTL corresponding to the speed of rotation of the free turbine of said engine; a correction device for correcting said measured speed NTL into a corrected value NTLcorr; third means for determining a preset value NTLpres corresponding to the preset value for the speed of rotation of the free turbine of the engine; and a computation unit for automatically computing, on the basis of said preset value NTLpres and of said corrected value NTLcorr, the operating commands which are applied automatically to said first means, wherein: said correction device implements a correction law which corrects said measured speed NTL to obtain, based upon the measured speed NTL of rotation of the free turbine of said engine by the second means, the corrected value NTLcorr exhibiting, at least in a frequency domain situated around at least a first torsional mode of said drivetrain, the same modulus as said preset value NTLpres and a phase which is opposite to the phase of said preset value NTLpres in such a way as to damp at least said first torsional mode of the drivetrain.