TM 9-2815-225-34&P 3-7. INSPECTION (Contd) b. Castings. (1) Inspect castings for cracks using a magnifying glass and bright lighting. (2) Refer to MIGI-68866 (Inspection Process, Penetrant Methods) and MIGG-6868 (Inspection Process, Magnetic Particles). (3) Closely check area around studs, pipe plugs, threaded inserts, and sharp corners.  Replace all cracked castings. (4) Inspect machined surfaces for nicks, burrs, or raised metal.  Mark damaged areas for repair or replacement. (5) Inspect all pipe plugs, pipe plug openings, screws, and screw openings for damaged or stripped threads. (6) Use a straightedge or surface plate and check all gasket mating surfaces, flanges on housings, and supports for warpage. Inspect mating flanges for discoloration, which may indicate persistent oil leakage. (7) Check all castings for conformance to applicable repair standards. c. Ball-Roller  Bearings.    See  TM  9-214  for  inspection  of  bearings.    Check  all  bearings  for  conformance  to  applicable  repair standards (Appendix F). d. Studs, Bolts, and Screws.  Replace studs, bolts, and screws if bent, loose, or threads are stretched or damaged. e. Gears. NOTE There  are  no  established  gear  teeth  wear  limits.    Replace  gears  if  any  obvious  physical damage to teeth or keyway slots is evident. (1) Inspect all gears for cracks using a magnifying glass and bright lighting.  No cracks are allowed. (2) Inspect gear teeth for apparent excessive wear, sharp edges, chips, burrs, and galled or pitted surfaces. (3) Check keyway slots for wear and/or damage. CAUTION Engine connecting rod bearings and main bearings are supplied in sets.  Replacement of a single bearing is not permitted.  If one bearing has failed, all bearings must be replaced. f. Bearings, Bushings, and Bushing-Type Bearings. (1) Check  all  bushings  and  bushing-type  bearings  for  secure  fit,  evidence  of  heating,  wear,  burrs,  nicks,  and  out-of-round condition. (2) Check for dirt in lubrication holes or grooves.  Holes and grooves must be clean and free from damage. g. Oil Seals.  Oil seals should always be replaced. h. Core Hole Expansion Plugs.  Inspect for leakage.  Replace plug when leakage is present. 3-8. WEAR LIMITS AND TOLERANCES Refer to Appendix F for engine wear limits and tolerances. 3-9. REPAIR a. General Instructions.  General procedures for repair of engine parts and components are detailed in steps b. through h. 3-5