NOVELTY - The method involves using at least two distinct primary portions (1, 2c) for making up an integral structure (3) including a reinforcing layer of fibers, fabrics or textiles and impregnating matrix (R1, R2). A thermoplastic sheet (4) is placed on at least one of the primary portions or in between the primary portions so as to make the interface of the integral structure. A source of heat is used to bond together the primary portions prior to the injection or infusion operation, at least locally in defined positions.    USE - Method of fabricating composite portion for use in aviation industry, aerospace structure, automotive industry or wind-energy industry.    ADVANTAGE - A better control or even to direct the flow of the impregnation matrix in integral structures can be obtained by using a thermoplastic sheet that serves to separate the zones that are to be impregnated, either to influence the flow of the matrix by defining a specific and preferred path, or to define zones for impregnating with different matrices. An integrated structure can be made using different matrix systems, thus suppressing production steps if two different matrices are used. The zones in a single integral structure that have properties and/or functions that differ can be defined and thus configuring more accurately the transition zones between the various domains of integral structures. The mechanical properties at the bonds between the various portions of a single integral structure are improved. The possibility of repairing composite elements can be realized with only the damaged portion being replaced using a thermoplastic sheet. There is no longer necessary to make up the integral structure with pre-impregnated elements. The localized and simplified delivery of heat onto the portion that is to be repaired in order to melt the thermoplastic sheet enables the damaged portions to be separated from the integral structure, and solidifies the thermoplastic sheet so as to establish a mechanical bond between the replacement portion and the remainder of the integral structure, thus providing simplicity in repairing process with small number of implementation steps. An integral structure can be repaired either with a portion that is previously been impregnated and solidified, or else with a portion comprising dry fibers that need to be impregnated and solidified, or with a pre-impregnated perform (Prepreg) that needs to be solidified.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for composite portion repairing process.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic perspective view illustrating operation of impregnating integral structure in fabrication process.    Primary portions (1, 2c)    Integral structure (3)    Thermoplastic sheet (4)    Impregnation matrix (R1, R2)