Hydrogen fuel delivery system

A fuel delivery system for a gas turbine engine, the fuel delivery system comprising:

• a combustor of a gas turbine engine core, the combustor being disposed after a compressor of a gas turbine engine and before a turbine of a gas turbine engine in axial flow series;
• a fuel vent outlet;
• a fuel delivery line for connection between a fuel tank and the combustor, the fuel delivery line configured to deliver a gaseous fuel in use;
• a fuel vent line arranged to connect the combustor and fuel delivery line to the fuel vent outlet;
• wherein
• the fuel delivery line comprises a fuel delivery valve, wherein the fuel vent line is connected to the fuel delivery line at a connection point between the combustor and the fuel delivery valve, the fuel delivery line absent an additional valve between the fuel delivery valve and the combustor;
• the fuel vent line comprises a fuel vent valve;
• a flame arrestor is provided in fuel flow in the fuel vent line between the combustor and the fuel vent outlet;
• and
• wherein the fuel delivery system comprises a controller configured to control the fuel delivery valve and fuel vent valve in accordance with an emergency shutdown schedule upon detection of an engine emergency, such as a shaft break or turbine failure;
• and
• wherein the emergency shutdown schedule comprises closing the fuel delivery valve to shutoff fuel flow through the fuel delivery line to the combustor, and opening the vent valve to vent fuel and hot combustion gas from the fuel vent outlet.