Patent ID: 7668639

Claim:
A method for optimization of a performance envelope which is used during a first time between overhauls initially authorized for an existing rotorcraft engine (M) to enable said engine (M) to be used in an optimized performance envelope which is used during a second time between overhauls that is different from said performance envelope initially authorized for said engine (M), comprising: compensating said optimization by a change to a total service life of said engine using an apparatus that includes a meter provided with a clock and a calculator wherein a real damage at a current instant ER 3 is determined by ER 3= ER 2 +K 2/TBO× D 2, where ER 2 is the real damage at a previous instant, K 2 is a deterioration coefficient of said engine between said previous and the current instant, TBO is said first time between overhauls and D 2 is a duration in which a monitored temperature has resulting from a power change between said previous and the current instant; and displaying a real damage on a display provided in a cockpit of the rotorcraft.