Figure 10-1.  Engine mounted on an overhaul stand.  2.  Dispose of all safety devices (safety wire, cotter pins,  etc.) as they are removed. Never use them a second  time. Always replace with new safety devices. 3.  All loose studs, and loose or damaged fittings, should  be carefully tagged to prevent being overlooked during  inspection. 4.  Always use the proper tool for the job. Use sockets  and box end wrenches wherever possible. If special  tools are required, use them rather than improvising. 1. Visual 2.  Structural NDT 3. Dimensional 1.  Abrasion—an area of roughened scratches or marks  usually caused by foreign matter between moving  parts or surfaces. 2.  Brinelling—one or more indentations on bearing races,  usually caused by high static loads or application of  force during installation or removal. Indentations are  rounded or spherical due to the impression left by the  contacting balls or rollers of the bearing. 3.  Burning—surface damage due to excessive heat. It is  usually caused by improper fit, defective lubrication,  or over-temperature operation. 4.  Burnishing—polishing of one surface by sliding  contact with a smooth, harder surface. Usually no  displacement nor removal of metal. 5.  Burr—a sharp or roughened projection of metal  usually resulting from machine processing. 6.  Chafing—a condition caused by a rubbing action  between two parts under light pressure that results in  wear. 7.  Chipping—breaking away of pieces of material, that  is usually caused by excessive stress concentration or  careless handling. 8.  Corrosion—loss of metal by a chemical or  electrochemical action. The corrosion products are  easily removed by mechanical means. Iron rust is an  example of corrosion. 9.  Crack—a partial separation of material usually caused  by vibration, overloading, internal stresses, defective  assembly, or fatigue. Depth may be a few thousandths,  to the full thickness of the piece. 10. Cut—loss of metal, usually to an appreciable depth  over a relatively long and narrow area, by mechanical  means, as would occur with the use of a saw blade,  chisel, or sharp-edged stone striking a glancing blow. 11. Dent—a small, rounded depression in a surface usually  caused by the part being struck with a rounded object. The inspection of engine parts during overhaul is divided  into three categories: Many defects on the engine components can be detected  visually, and a determination of airworthiness can be made  at this time. If, by visual inspection, the component is  determined to be unairworthy, the part is rejected, and no  further inspection or repair is required. Structural failures can  be determined by several different methods. Magnetic parts  can readily be examined by the magnetic particle method.  Other methods, such as dye penetrate, eddy current, ultra  sound, and X-ray, can also be used. The first two methods  are aimed at determining structural failures in the parts,  while the last method deals with the size and shape of each  part. By using very accurate measuring equipment, each  engine component can be dimensionally evaluated and  compared to service limits and standards (tolerances) set by  the manufacturer.  Visual inspection should precede all other inspection  procedures. Parts should not be cleaned before a preliminary  visual inspection, since indications of a failure may often be  detected from the residual deposits of metallic particles in  some recesses in the engine. Several terms are used to describe defects detected in engine  parts during inspection. Some of the more common terms  and definitions are: Visual Inspection Inspection Process 10-3