PURPOSE: To manufacture a nozzle cover at low cost by casting it as one-piece having first and second manifolds and a nozzle holder and providing the manifold with means for supplying gas to the nozzle holder.

CONSTITUTION: A combustor 62 has a housing 64 secured with a nozzle cover 66 investment cast as an ellipsoid exhibiting maximum strength to a specified quantity of material. A gas fuel manifold 68 is integrated with an air manifold 70 and a liquid fuel channel 74 is formed while being aligned with respective nozzle holders. A nozzle holder 72 is formed integrally with the interfaces to the manifold 68, 70 wherein an air joint 76 communicates with the air manifold 70 and a gas fuel joint communicates with the air manifold 68. The nozzle cover 66 is used as cast with the exception of hermetic sealing, boring and threading works.