Method for testing a rotor blade component of a rotor blade for a wind power installation, comprising: - dividing a rotor blade component of a rotor blade for a wind power installation into two, three or more rotor blade component segments (350, 450, 350', 450`), - forming cutouts (211, 311, 411, 611a, 611b, 311',411') in a connection interface (210, 310, 410, 510a, 510b, 610, 310', 410') at a connection end of one of the rotor blade component segments (350, 450, 350', 450`) - testing the rotor blade component segment (350, 450, 350', 450`) at a test stand, - wherein spacers are arranged on a face surface (212, 312, 412, 512a, 512b, 612a, 612b, 312', 412') of the connection interface (210, 310, 410, 510a, 510b, 610, 310', 410') in the region of openings of the cutouts (211, 311, 411, 611a, 611b, 311', 411'), and/or - a filler compound is applied and/or arranged on a face surface (212, 312, 412, 512a, 512b, 612a, 612b, 312', 412') of the connection interface (210, 310, 410, 510a, 510b, 610, 310', 410') in the region of openings of the cutouts (211, 311, 411, 611a, 611b, 311', 411'), in particular to compensate unevennesses, characterized in that - planar surfaces are produced on a face surface (212, 312, 412, 512a, 512b, 612a, 612b, 312', 412') of the connection interface (210, 310, 410, 510a, 510b, 610, 310', 410') in the region of openings of the cutouts (211, 311, 411, 611a, 611b, 311', 411`), - wherein the planar surfaces lie on two or more different planes, and - wherein the distances of the planar surfaces from a common reference plane are determined and the thicknesses of the spacers and/or the filler compound are adjusted to these measured distances. - dividing a rotor blade component of a rotor blade for a wind power installation into two, three or more rotor blade component segments (350, 450, 350', 450`), - forming cutouts (211, 311, 411, 611a, 611b, 311',411') in a connection interface (210, 310, 410, 510a, 510b, 610, 310', 410') at a connection end of one of the rotor blade component segments (350, 450, 350', 450`) - testing the rotor blade component segment (350, 450, 350', 450`) at a test stand, - wherein spacers are arranged on a face surface (212, 312, 412, 512a, 512b, 612a, 612b, 312', 412') of the connection interface (210, 310, 410, 510a, 510b, 610, 310', 410') in the region of openings of the cutouts (211, 311, 411, 611a, 611b, 311', 411'), and/or - a filler compound is applied and/or arranged on a face surface (212, 312, 412, 512a, 512b, 612a, 612b, 312', 412') of the connection interface (210, 310, 410, 510a, 510b, 610, 310', 410') in the region of openings of the cutouts (211, 311, 411, 611a, 611b, 311', 411'), in particular to compensate unevennesses, - planar surfaces are produced on a face surface (212, 312, 412, 512a, 512b, 612a, 612b, 312', 412') of the connection interface (210, 310, 410, 510a, 510b, 610, 310', 410') in the region of openings of the cutouts (211, 311, 411, 611a, 611b, 311', 411`), - wherein the planar surfaces lie on two or more different planes, and - wherein the distances of the planar surfaces from a common reference plane are determined and the thicknesses of the spacers and/or the filler compound are adjusted to these measured distances.