Patent ID: 7246495

Claim:
A system for controlling a gas-turbine engine having at least one turbine, comprising: a first group of two speed sensors installed at or near the engine and each generating an output indicative of a rotational speed of the turbine; a second group of two speed sensors installed at or near the engine and each generating an output indicative of the rotational speed of the turbine; a first control channel inputting the outputs of the first group of speed sensors and controlling supply of fuel to the engine based on the inputted outputs; and a second control channel inputting the outputs of the second group of speed sensors and controlling supply of fuel to the engine based on the inputted outputs, in place of the first control channel when an abnormality condition arises in the first control channel; wherein the first and second control channels include: three-value comparator inputting three of four outputs generated by the first and second groups of speed sensors and comparing them with each other to determine whether at least two of the three outputs are within a range that allows at least two outputs to be considered identical; and four-value comparator inputting a result of comparison at the three-value comparator and a remaining one of the four outputs, comparing one of the at least two of the three outputs with the remaining one when the at least two of the three outputs are determined to be within the range, while comparing each of the three outputs with the remaining one when the three outputs are determined not to be within the range and determining whether at least one of the four outputs is the output that is usable in the fuel supply control.