Patent ID: 7853441

Claim:
A method for updating a gas turbine engine reference model comprising the steps of: determining whether an absolute difference between a calculated time constant of a sensor and an assumed sensor model time constant is outside a tolerance value; and responsive to determining that the absolute difference is outside the tolerance value, updating the assumed sensor model time constant with the calculated time constant of the sensor; measuring a first engine parameter with a sensor; applying a first time-derivative to the first measured engine parameter data; applying a second time-derivative to the first measured engine parameter data; calculating a first instantaneous time constant with the second time-derivative of the first measured engine parameter data; storing the first instantaneous time constant in a memory; measuring a second engine parameter with the sensor; applying a first time-derivative to the second measured engine parameter data; applying a second time-derivative to the second measured engine parameter data; calculating a second instantaneous time constant with the second time-derivative of the second measured engine parameter data; storing the second instantaneous time constant; and selecting the calculated time constant from the instantaneous time constants.