Fuel metering system proportional bypass valve error compensation system and method

A fuel metering system for control fuel flow to a gas turbine engine, comprising:

• a fuel supply line having an inlet adapted to couple to a fuel source and an outlet adapted to couple to the gas turbine engine;
• a metering valve positioned in flow-series in the supply line, the metering valve producing a differential pressure thereacross when fuel flows therethrough;
• a bypass flow line coupled to the fuel supply line upstream of the metering valve for bypassing a portion of the fuel in the supply line back to the inlet;
• a proportional bypass valve positioned in flow-series in the bypass flow line and configured to control flow therethrough to maintain a substantially constant differential pressure across the metering valve, the substantially constant differential pressure including a differential pressure error produced by the proportional bypass valve;
• and
• a control circuit adapted to receive a fuel flow command representative of a desired fuel flow and operable to (i) determine the differential pressure error and (ii) adjust the metering valve, based at least in part on the determined differential pressure error and the fuel flow command, to supply fuel through the metering valve to at the desired fuel flow.