Abstract: A fuel system (10) for a gas turbine engine (18) having a shaft (30) and requiring fuel to be supplied at a first rate for engine start up, the fuel system (10) including: a main fuel pump (14) for providing fuel to the gas turbine engine (18), the main fuel pump (14) having an output varying with shaft speed, the output being at a windmilling rate when the engine (18) is windmilling, the windmilling rate being less than the first rate; and an auxiliary fuel pump (40) for providing fuel to the gas turbine engine (18) and having an auxiliary output rate greater than or equal to the difference between the first rate and the windmilling rate. A method of operating such a fuel system (10) is also disclosed.

Abstract: A fuel control system for a gas turbine engine is disclosed that includes a flow path carrying fuel from a fuel source to a combustion chamber, an ecology valve 124 for removing a quantity of fuel from the flow path, the ecology valve 124 being shiftable in a first direction from a first position to a second position and in a second direction from said second position to said first position and a fuel line 115 connected between the flow path and the ecology valve 124 for moving fuel between the flow path and the ecology valve 124 to bias the ecology valve 124 toward the second position, where the fuel line 115 is configured, such as by the inclusion of an orificed check valve 150 therein, to allow fuel to move therethrough away from the ecology valve 124 at a greater rate than toward the ecology valve 124.