The background of this paper is to find out the predominant types of defects that occurs during the fabrication of pump fed rocket engines. Pump fed rocket engine which works on gas generator cycle is used in operational launch vehicles. The number of non-conformances are to be reduced to improve the reliability of the engine. The non-conformances reported during fabrication of twenty numbers of the engine realised over a period of four yearsare classified under different heads. Pareto analysis was carried out and found that the non-conformances due to weld shrinkage (process limitation), operator mistakes (human error) and free condition ovality (raw material) are the pre-dominant ones. The suggestions for process improvement leading to reduction in non-conformances per engine are also highlighted in this paper.