TM 9-2815-225-34&P 3-37.  CRANKSHAFT REPAIR (Contd) LOCATION/ITEM ACTION REMARKS b.  Inspection (Contd) f.  Whenever structural damage to an engine has occurred, such as piston or valve breakage, a magnetic inspection should be performed on crankshaft as follows: NOTE Ampere turns in amperage flowing through coil are multiplied by number of turns in coil; the currents listed below are for 4-turn coil. DIRECTION OF DEFECT DIRECTION OF DEFECT LONGITUDINAL CIRCUMFERENTIAL DC or Rectified 1200 Amp 3600-4000 amp turns AC Equipment 1400 Amp 4200-4700 amp turns Magnetizing Method Head Shot Coil Shot g.  Wet complete surface with magnetic particle suspension before applying currents. h.  Use the following directional magnetizing currents for crankshaft magnetic inspection or Magnaflux inspection: i.  Flow magnetic particle Turn current on coil and move suspension over part in advance coil full length of part. of placing part through coil. (1) If shaft parts are within 2 in. (5.1 cm) or 3 in. (7.6 cm) of the coil inside diameter, ample magnetism will be obtained if 3 shots of current are passed through coil at each end and center of part length. (2) The limits of acceptability, Obvious cracks and circumferential unless otherwise stated, apply or transverse defects are not only to light slag or oxide acceptable. stringers usually defined as inherent inclusions. 3-156