TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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c. Castings. (1) Inspect all ferrous (cast iron, steel, etc.) castings for cracks with magnetic-particle in- spection equipment. Inspect all nonferrous (aluminum castings) for cracks using flourescent-penetrant inspection equipment. Suspected cracks in the nonferrous casting can also be inspected with a spot check dye penetrate or a magnifying glass (five power magnification minimum) and a strong light or a dye check method. Check particularly the areas adjacent to studs, pipe plugs, or threaded inserts and in sharp corners and fillets. (2) Inspect machined surfaces of castings for nicks, burs, or raised metal. Mark damaged areas for repair. (3) Check all mating flanges and mounting pads with a straight edge or surface plate for warpage. Inspect mating flanges and mounting pads for discoloration which may indicate persistent oil leakage. (4) Inspect all tapped openings for stripped or damaged threads. (5) Check all castings for conformance to the applicable repair and rebuild standards. d. Ball and Needle Bearings. Refer to TM 9- 214 for inspection of anti friction bearings. Check all bearings for conformance to the ap- plicable overhaul standards. e. Studs. Inspect all studs for damaged or stripped threads, bent or loose condition, or for any signs of stretching. f. Dowel Pins. Inspect dowel pins for looseness or damage. Mark loose pins for repair. g. Gears and Shafts. Note. There are no established wear limits for gear teeth and splines. Good judgment is required to determine need for replacement. (1) Inspect all gears and shafts for cracks using magnaflux equipment. When magnaflux equipment is not available, use a magnifying glass (five power magnification minimum) and a strong light. (2) Inspect all gear teeth and splines for wear, sharp fins, burs, and galled or pitted surfaces. (3) Inspect shaft and gear hub splines for damage, wear, and for fit with splines on mating parts. Mating splines must match without binding or looseness. (4) Check all gears and shafts for con- formance to the applicable overhaul standards. h. Bushings, Liners, and Bushing-type Bearings. (1) Check all bushings, liners, and bushing- type bearings for secure fit in their respective casting or mating part, and for evidence of heating, which may be indicated by discoloration of bushing or bearing surface. (2) Inspect for wear, burs, nicks or out-of- round condition. (3) Check for dirt in lubrication holes or grooves. Holes and grooves must be clean and free from damage to insure proper lubrication. (4) Inspect thrust faces of bushing-type bearings for wear and by temporarily assembling mating parts and checking end play with a feeler gage inserted between the thrust faces. (5) Check for conformance to the applicable overhaul standards. i. Oil Seals. All oil seals must be replaced at engine overhaul. Generally, metal encased oil seals are long-life parts and do not have to be replaced during field repair if inspection in- dicates seals are in good condition. (1) Inspect for damage to the thin feather edge of oil seal which contacts rotating part. (2) Inspect sealing feather edge for softness and pliability. (3) Replace damaged or questionable seals during field engine repair. j. Helical-coil and Screw Thread Inserts. (1) Description. To permit higher stresses on studs and bolts which are set in aluminum castings, it is common practice to install insets of a stronger metal into which the studs or bolts are threaded. Helical-coil and screw thread inserts are designed to perform this function. The in- serts are spiral steel coils having a right hand thread-shaped form on the inside and on the outside of the coils. A bar or tang at the bottom end of the coil, which is engaged by an inserting tool, is used for threading the insert into the casting. Some inserts have a serrated tooth section at the top end of the coil to stake them in place in the castings. Other inserts have turns at the center of the coil in the form of a hexagon. This provides a locking effect when the stud or bolt is threaded into the insert. (2) Inspection. Inspect all helical-coil and screw thread inserts for secure fit in the casting and for galled or stripped threads. k. Painted Parts. Straighten parts as 6-4