A system includes an engine case for a gas turbine engine defined around a longitudinal axis. An access opening is defined through the engine case for access from outside the engine case to a space inside the engine case. A combustor is housed in the space inside the engine case. The combustor includes an inner annular wall and an outer annular wall radially outboard from the inner annular wall. The inner annular wall includes a first rail on an upstream end thereof. The outer annular wall includes a second rail on an upstream end thereof. The first and second rails each include a respective access portion configured to receive line replaceable injector components from through the access opening of the engine case into the first and second rails to form a combustor dome of the combustor.