A combustor apparatus defines a combustion zone where air and fuel are burned to create high temperature combustion products. The combustor apparatus includes an outer wall, coupling structure on the outer wall adjacent to a fuel inlet opening thereof, a fuel injection system, a fuel feed assembly, and a fitting member. The fuel injection system provides fuel to be burned in the combustion zone. The fuel supply structure includes a threaded inner surface formed from a first material. The fuel feed assembly includes a fuel feed pipe that extends through the fuel inlet opening in the outer wall and has an outlet portion formed from the first material and that is threadedly engaged with the fuel supply structure, and an inlet portion affixed to the outlet portion and formed from a second material. The fitting member secures the fuel feed assembly relative to the outer wall.