Wednesday, June 20, 2012

VISUAL INSPECTION

             Visual inspection is the most common form of airplane inspection. Visual inspection can find a wide variety of component and material surface discontinuities, such as cracks, corrosion, contamination, surface finish, weld joints, solder connections, and adhesive disbonds. The results of a visual inspection may be improved with the use of applicable combinations of magnifying instruments, boroscopes, light sources, video scanners, and other devices. The use of optical aids for visual inspection is recommended. Optical aids magnify discontinuities that cannot be seen by the unaided eye and also allow inspection in inaccessible areas.
                    Personnel that do visual inspection tasks do not need to have certification in nondestructive inspection.
                                                      Visual Aids
                    Structure and components that must be routinely examined are sometimes difficult to access. Visual inspection aids such as a powerful flashlight, a mirror with a ball joint, and a 10 power magnifying glass are needed for the inspection.
                   Flashlights used for visual inspection should be suitable for industrial use and, where applicable, safety approved for use in hazardous atmospheres such as airplane fuel tanks. These characteristics should be considered when selecting a flashlight: foot-candle rating; explosive atmosphere rating; beam spread (adjustable, spot, or flood); efficiency (battery usage rate); brightness after extended use; and rechargeable or standard batteries. Inspection flashlights are available in several different bulb brightness levels:
(a) Standard incandescent (for long-battery life).
(b) Krypton (for 70% more light than standard bulbs).
(c) Halogen (for up to 100% more light than standard bulbs).
(d) Xenon (for over 100% more light than standard bulbs)
(3) An inspection mirror is used to view an area that is not in the normal line of sight. The mirror should be of the applicable size to easily see the component and a swivel joint tight enough to keep its position.
(4) A single converging lens is often referred to as a simple magnifier. Magnification of a single lens can be found by the equation M = 10/f. In this equation, “M” is the magnification, “f” is the focal length of the lens in inches, and “10” is a constant that represents the average minimum

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