Process of detection and preventive control of defects in mass produced composite material parts, comprising the following steps: a) automatically obtaining, from pulse-echo ultrasonic scanning, representative parameters of backwall and intermediate echo signal results in each cell of a mesh predefined on the part or predetermined areas thereof; b) storing said parameters in a database; and c) statistically analyzing the stored parameters corresponding to certain areas of a certain part for: c1) detecting isolated and significant alterations in the part manufacturing process generating porosity defects, either overall or in layers, in each analyzed area by means of classic sample mean and standard deviation charts and identifying the analyzed areas with isolated and significant alterations as areas with high defect generation probability, c2) detecting slow and permanent alterations in the part manufacturing process generating porosity defects, either overall or in layers, in each analyzed area by means of moving average or exponentially weighted moving average (EWMA) charts having improved sensitivity and identifying the analyzed areas with slow and permanent alterations as areas with high defect generation probability, c3) if no alteration is detected in steps c1) and c2) calculating the process capability index Cpk of the analyzed cells of the mesh by means of the following expression: C p k = smaller value o f C p k upper, C p k lower, where C p k upper = U T L − X / 3 σ and C p k lower = X − L T L / 3 σ, where UTL= Upper Tolerance Limit LTL= Lower Tolerance Limit X= sample mean and σ= standard deviation for detecting areas where the manufacturing process presents low probability of the occurrence of defects at independently stored over time backwall and intermediate echo amplitude populations in order to identify them as areas susceptible of inspection by sampling when Cpk>1. a) automatically obtaining, from pulse-echo ultrasonic scanning, representative parameters of backwall and intermediate echo signal results in each cell of a mesh predefined on the part or predetermined areas thereof; b) storing said parameters in a database; and c) statistically analyzing the stored parameters corresponding to certain areas of a certain part for: c1) detecting isolated and significant alterations in the part manufacturing process generating porosity defects, either overall or in layers, in each analyzed area by means of classic sample mean and standard deviation charts and identifying the analyzed areas with isolated and significant alterations as areas with high defect generation probability, c2) detecting slow and permanent alterations in the part manufacturing process generating porosity defects, either overall or in layers, in each analyzed area by means of moving average or exponentially weighted moving average (EWMA) charts having improved sensitivity and identifying the analyzed areas with slow and permanent alterations as areas with high defect generation probability, c3) if no alteration is detected in steps c1) and c2) calculating the process capability index Cpk of the analyzed cells of the mesh by means of the following expression: C p k = smaller value o f C p k upper, C p k lower, where C p k upper = U T L − X / 3 σ and C p k lower = X − L T L / 3 σ, where UTL= Upper Tolerance Limit LTL= Lower Tolerance Limit X= sample mean and σ= standard deviation for detecting areas where the manufacturing process presents low probability of the occurrence of defects at independently stored over time backwall and intermediate echo amplitude populations in order to identify them as areas susceptible of inspection by sampling when Cpk>1. c1) detecting isolated and significant alterations in the part manufacturing process generating porosity defects, either overall or in layers, in each analyzed area by means of classic sample mean and standard deviation charts and identifying the analyzed areas with isolated and significant alterations as areas with high defect generation probability, c2) detecting slow and permanent alterations in the part manufacturing process generating porosity defects, either overall or in layers, in each analyzed area by means of moving average or exponentially weighted moving average (EWMA) charts having improved sensitivity and identifying the analyzed areas with slow and permanent alterations as areas with high defect generation probability, c3) if no alteration is detected in steps c1) and c2) calculating the process capability index Cpk of the analyzed cells of the mesh by means of the following expression: C p k = smaller value o f C p k upper, C p k lower, where C p k upper = U T L − X / 3 σ and C p k lower = X − L T L / 3 σ, where UTL= Upper Tolerance Limit LTL= Lower Tolerance Limit X= sample mean and σ= standard deviation where UTL= Upper Tolerance Limit LTL= Lower Tolerance Limit X= sample mean and σ= standard deviation