An engine failure caused by erosion-corrosion of a fuel manifold was investigated. The surface of the boost elements (impeller and its cover) of the main fuel pump showed the wear damage by Fe-based particles. This incident reduced the fuel pressure abruptly, and led to engine shut-down. This was confirmed by EDX analysis of the rubbed surface of the boost elements and the metal chips collected form fuel filter. To find the possible source of Fe-based particles the whole fuel system of the aircraft was reviewed. On the basis of this review the fuel manifold attached to the main fuel pump was selected for in-depth analysis. The manifold was cut and its inner surface was examined visually with the aid of a stereoscope revealing internal penetration of the welding metal. This internal welding bead was attacked by erosion-corrosion, partially lifted-off and generated particles. The particles separated from the internal bead and were carried in the fuel. On entering the main fuel pump these particles caused the wear damage. The inner surface of randomly chosen manifolds showed internal welding metal too. Therefore optimization of the welding parameters during the joining process of the manifold was proposed as a remedial action.