A method for reactivating a hybrid turboshaft engine, said hybrid turboshaft engine being comprised in an architecture of a propulsion system of a multi-engine helicopter, said architecture having turboshaft engines connected to a power transmission gearbox, said hybrid turboshaft engine being capable of operating in at least one standby mode during a stable cruise flight of the helicopter and a second turboshaft engine operating during the stable cruise flight,
- said architecture further comprising at least a first reactivation system and a second reactivation system configured to control the hybrid turboshaft engine, each reactivation system comprising an electric machine connected to the hybrid turboshaft engine for rotating said hybrid turboshaft engine, and at least one source of electrical power for said electric machine,
- said method comprising:
- driving the hybrid turboshaft engine in a rapid reactivation mode, wherein said hybrid turboshaft engine is rotated at a speed of 105% of a nominal speed of a gas generator of said hybrid turboshaft engine in a period of less than 10 seconds;
- driving the hybrid turboshaft engine in a normal reactivation mode, wherein said hybrid turboshaft engine is rotated to a speed in the range of between 80% and 105% of the nominal speed of the gas generator of said hybrid turboshaft engine in a period in the range of between 10 seconds and 60 seconds;
- driving the hybrid turboshaft engine in an assisted super-idle standby mode, in which the hybrid turboshaft engine is rotating to a speed in the range of between 20% and 60% of the nominal speed of the gas generator of said hybrid turboshaft engine;
- driving the hybrid turboshaft engine in a turning standby mode, in which the gas generator of said hybrid turboshaft engine is rotating to a speed in the range of between 5% and 20% of the nominal speed of the gas generator of said hybrid turboshaft engine,
- said first reactivation system being configured to drive said hybrid turboshaft engine in the rapid reactivation mode, the normal reactivation mode, and at least one of the assisted super-idle standby mode or the turning standby mode;
- and
- said second reactivation system being configured to drive said hybrid turboshaft engine in said normal reactivation mode.