Abstract: A method of re-trimming an engine control parameter. Measure an engine parameter over time. Calculate change in the measured parameter per engine cycle. Determine change of thrust due to the calculated change in the measured parameter from a reference database. Define a new trim value for the engine control parameter that is a function of the change of thrust. Apply the new trim value to the engine control parameter.

Abstract: A method of detecting an ice shedding event in a gas turbine engine, the engine having a rotor comprising a compressor drivingly connected via a shaft to a turbine; the method for detecting an ice shedding event comprising the steps of measuring the temperature at regular intervals and where a temperature drop of at least 20 degrees per second is recorded, producing a signal indicative of an ice shedding event and sending the signal to an indicator device. Advantageously, the engine may then be inspected for damage associated to an ice impact rather than other foreign object ingestion event or fuel flow irregularity. Alternatively, instead of temperature, pressure may be measured and a pressure drop of at least 20 kPa per second is indicative of an ice shedding event.