Patent ID: 7340901

Claim:
A method for correcting and/or preventing an overspeed condition during on-speed operation of an auxiliary power unit in an aircraft comprising: measuring the speed of the auxiliary power unit; comparing the speed to a predetermined speed reference point to determine a speed error; calculating a commanded fuel flow value from the speed error; comparing the commanded fuel flow value to a maximum fuel schedule to get a commanded fuel flow upper limit value; determining a blowout prevention rate; comparing the commanded fuel flow upper limit value to a predetermined minimum fuel schedule to determine a possibility of a blowout at the commanded fuel flow upper limit value; and delivering fuel to the auxiliary power unit at the blowout prevention rate when the possibility of a blowout is present, thereby preventing blowout of the auxiliary power unit; and delivering fuel to the auxiliary power unit at said commanded fuel flow upper limit value when the possibility of blowout is not present.