A combustor apparatus defining a combustion zone where air and fuel are burned to create high temperature combustion products. The combustor apparatus comprises an outer wall including a fuel inlet opening for receiving a fuel feed pipe. A coupling assembly is engaged with the fuel feed pipe at the fuel inlet opening to attach the fuel feed pipe to the outer wall. A fuel injection system is located in the interior volume of the outer wall and comprises fuel supply structure including a fuel feed block having a fuel intake passage aligned with the outlet portion of the fuel feed pipe. A coupling fastener is engaged against an exterior outer face of the fuel feed block to create a sealed coupling for containing fuel passing from the fuel feed pipe into the fuel feed block, and to secure the fuel feed block relative to the coupling assembly.