The Boeing Company

Mark B Simpson

Dennis P Sarr

Patrick Lee Anderson

A probe (20) that inspects a countersunk hole (21) in a conductive body, such as an aircraft part (22), is provided. A plurality of nested cylinders form an electrode cartridge (54) with a countersink portion (74) having a frustoconical shape and a hole portion (76) having a cylindrical shape. A plurality of lower hole electrode strips (72) are mounted on a lower hole cylinder (110) and a plurality of upper hole electrode strips (70) are mounted on an upper hole cylinder (116). A plurality of lower countersink electrode strips (68) are coupled to a lower countersink cylinder (124) and a plurality of upper countersink electrode strips (66) are coupled to an upper countersink cylinder (132). A dielectric layer (64) covers a plurality of measuring electrode tips (67, 69, 71 and 73) and an outer surface (150) of the hole and countersink portions (76 and 74). A grounding electrode (158) is mounted on the upper hole cylinder ( 116). A ground wire (162) is coupled to the grounding electrode (158) and extends beyond the dielectric layer (64). When probe (20) is inserted into the countersunk hole (21), the countersunk hole (21) is grounded by the ground wire (162). A charging current applied to the measuring electrode strips (66, 68, 70 and 72) in a sequential manner, causes the measuring electrode tips (67, 69, 71 and 73) form fringe field capacitors with the ground wall of the countersunk hole (21). The fringe field capacitors charge up at a rate dependent, in part, upon the distance between the probe (20) and the wall of the countersunk hole (21). Sufficient rate measurements are made of the distance between the probe (20) and the wall of the countersunk hole (20) to permit another device (30) to determine whether the geometry and orientation of the countersunk hole (21) are within engineering specifications.

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Everett, WA, United States of America

Mark B Simpson