X-ray or gamma ray systems or devices – Specific application – Absorption
Reexamination Certificate
2001-08-31
2003-10-21
Oen, William (Department: 2855)
X-ray or gamma ray systems or devices
Specific application
Absorption
Reexamination Certificate
active
06636581
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to inspection methods for identifying structural particularities and, more particularly, to an inspection method for identifying defects, including cracks and corrosion, in aircraft.
BACKGROUND
“Aging aircraft” is a Federal Aviation Administration (FAA) classification for a commercial aircraft with over 36,000 cycles on its airframe, or 15 years of service life, or a combination of cycles and years of service life. A cycle comprises a takeoff and landing. Worldwide, there are thousands of aircraft in the “aging aircraft” category.
The FAA requires that an aging aircraft be inspected for cracks and corrosion at regular intervals. Current known inspection techniques use visual inspection. To prepare for a visual inspection, the interior of the fuselage must be stripped of seats, bins, galleys, panels, and insulation. Further, the visual inspection process itself typically takes several personnel ten days or more to complete. Moreover, it has been found that a crack may not be identified with a visual inspection until it reaches a length of two to four inches. Additionally, cracks and corrosion on the interior layers or frame members cannot be seen at all using visual inspection. Overall, the visual inspection technique is slow, laborious, damaging to aircraft materials, and less than optimally effective for crack and corrosion detection.
Alternative non-invasive inspection techniques, such as x-ray inspection, would provide superior detection of cracks and corrosion in an aircraft fuselage. Additionally, the aircraft's panels and insulation would not have to be removed. However, there is currently no practical way of performing a comprehensive x-ray inspection of an aircraft. To obtain an x-ray image through a fuselage (or wing) requires that an x-ray source or emitter and an x-ray detector, located inside and outside of the fuselage respectively, be positioned with respect to each other at the time that the images are obtained.
Accordingly, those skilled in the art have long recognized the need for a new method of efficiently performing an inspection of an aircraft. The present invention clearly fulfills these and other needs by providing the means to perform an efficient and non-invasive inspection, reducing the time and cost required to prepare an aircraft for inspection, reducing the time to perform the inspection, and increasing the effectiveness and quality of the inspection. The structure and method of the present invention may also be used to identify components, or particularities, of any structure, including, for example, ships and buildings.
SUMMARY
Briefly, and in general terms, the present invention resolves the above and other problems by providing an inspection method for inspecting a structure and identifying particularities, such as defects, in the structure. The inspection method includes: positioning two inspection devices at a pre-determined distance from each other, one of the inspection devices inside of the structure and the other inspection device outside of the structure, wherein the two inspection devices comprise a detector inspection device and a source inspection device; collecting data, such as images, of a portion of the structure located between the source and the detector; moving the inspection devices on the inside and the outside of subsequent portions of the structure to be inspected while maintaining an approximate distance between the inspection devices without reliance on a physical or optical link between the inspection devices; and collecting data of the additional portions of the structure located between the inspection devices.
In accordance with an aspect of the present invention, the inspection devices are automatically moved to each portion of the structure to be inspected according to an inspection sequence that controls the movement of the inspection devices along the structure. In an embodiment, the inspection sequence is a programmed inspection sequence. The programmed inspection sequence that controls movement of the inspection devices along the structure may be produced at some time prior to the inspection by an operator moving one or both of the inspection devices through data collection positions and programming the data collection positions into the inspection sequence. In an embodiment, during the creation of the programmed inspection sequence, sections of the inspection sequence that correspond to similar or substantially similar portions of the structure are repeated within the inspection sequence during the programming, thereby, among other things, simplifying the programming of the inspection sequence.
In an embodiment, the programmed inspection sequence that controls movement of the inspection devices along the structure is produced from surface data generated from visual surveying equipment. In another embodiment, the programmed inspection sequence is produced from surface model data derived from Computer Assisted Design (CAD) data. In yet another embodiment, the source inspection device and the detector inspection device are manually moved to each portion of the structure to be inspected.
In accordance with another aspect of the present invention, the source inspection device comprises an x-ray source and the detector inspection device comprises an x-ray detector. In an embodiment, the source is mounted on a first gantry and the detector is mounted on a second gantry. A gantry is a motion control device that allows positioning of an inspection device at a desired position. A gantry consists of two or more linked mechanical structures, the relative positions of which are controlled by actuators. A construction crane or a “cherry picker” are examples of gantries. The first and second gantries are synchronized to move in coordinated motion with each other under the direction of a gantry control system. Alternatively, it is not required that both gantries move in strict synchronization; it is only required that the inspection devices stop at prescribed relative positions so that satisfactory data, such as images, can be acquired. Either of these types of relative motions will be referred to herein as synchronized motion.
In another embodiment, one inspection device is mounted on an interior gantry that utilizes a track assembly and the other inspection device is mounted on an exterior gantry that utilizes a rover vehicle. A rover vehicle is a ground-based vehicle that carries the external gantry from point to point. In an embodiment, the rover has four-wheel independent steering to increase maneuverability.
In accordance with another aspect of the present invention, the inspection devices are initialized at home positions that allow for direct or visual contact between the inspection devices. In an embodiment, the task of initializing a gantry or inspection device consists of moving the inspection device to a known location and entering into the motion control system the coordinates of the known location either in the gantry or the coordinate system of the structure to be inspected, e.g., the aircraft coordinate system. In another embodiment, the task of initializing a gantry or inspection device consists of moving the gantry to a known internal configuration, or home position, and entering into the motion control system the gantry coordinate system values for that position. In yet another embodiment, the task of initializing a gantry or inspection device consists of moving two inspection devices to specific locations relative to each other and entering into the motion control system the relative coordinates of one or both inspection devices or gantries.
In an embodiment, the structure that the inspection method is designed to inspect comprises an aircraft. Additionally, in an embodiment the particularities that the inspection method identifies comprise cracks and corrosion. In an alternative embodiment, the structure that the inspection method is used to inspect comprises any structure, including, but not limited to, a building or a ship.
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Oen William
White & Case LLP
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