Method and device for monitoring the health condition of a turbine engine of an aircraft

The method involves increasing speed of rotation of a gas generator until a turbine engine develops a maximum power. The speed of rotation of the gas generator is reduced until the reduced speed of rotation reaches a test value. An aircraft is stabilized by keeping the reduced speed of rotation constant for a stabilization duration. An operating margin is determined by using a monitoring value and installation losses corresponding to the reduced speed of rotation. The engine is overhauled (STP3) if the operating margin is less than a limit threshold defined by a manufacturer. An independent claim is also included for a health check device.