TM 1-1500-204-23-3 NOTE For chip detectors, first disconnect the electrical connector. (2) Removal  of  two-piece  chip  detectors.    Disconnect  electrical  connector  from  the  detector.    Press removable  center  insert  in,  turn  counterclockwise  and  remove  from  the  valve  body.    To  remove  valve  body  when necessary, cut lockwire and unscrew, draining the oil. (3) Inspection.  When removing plug or detector, care must be taken not to contaminate the magnetic gap.    Visually  check  the  gap  for  metal  accumulation.    The  metal  deposits  may  be  chips,  flakes,  and  splinters,  or  in  a granular form.  Presence of metal may indicate need for further investigation and corrective action; refer to applicable maintenance manual. WARNING Drycleaning solvent is flammable and solvent vapors are toxic.  Use P-D-680 Type II Solvent in a well-ventilated area.  Keep away from open flames.  Avoid prolonged solvent contact with skin. (4) Cleaning.  Clean magnetic plug or chip detector with drycleaning solvent P-D-680, Type I, or as specified in the aircraft maintenance manual.  Then wipe with a clean lint-free cloth. (5) Test.  Prior to testing, visually check plug body for worn, stripped or damaged threads, and bayonet features as applicable.  Replace as required.  If leakage was observed prior to removal of the center insert of a chip detector of this type, or the still installed valve body leaks, replace with new seals or chip detector as necessary.  Inspect plug or detector magnet and gap.  If deformed, or magnet is chipped or cracked, replace with a new unit.  Test procedures are provided in the following paragraphs. (a) Magnetic ability test.  Use a standard steel paper clip, or equivalent, placed across the magnetic gap. If test piece is held in place, the plug or detector is satisfactory for use.  If the test piece is not held in place, replace plug or detector with a new one. NOTE Make certain that test piece is not magnetized. (b) Electrical test.  This test is to check chip detectors and aircraft wiring.  Test procedures are as follows: 1 Connect detector to aircraft wiring. 2 Ground body of detector to aircraft. 3 Apply power. 4 Warning  light  should  not  illuminate.    If  light  comes  on,  break  ground  between  body  and aircraft.  If light continues to burn, wiring is faulty.  If light goes out, replace chip detector. 5 If warning light does not come on, then temporarily place test piece across magnetic gap. The light should come on.  If light does not come on, recheck bridging connection and ground connection.  If light still does not come on check circuit wiring and components, including the light. (6) Installation  for  magnetic  plugs  and  chip  detectors  without  center  insert.    Replace  seal  if  damaged  or deteriorated, screw plug in and torque as specified in the applicable maintenance manual and then lockwire.  For chip detector, connect electrical lead. (7) Installation  for  chip  detectors  with  removable  center  insert.    Replace  seals  it  damaged  or  deteriorated. Position  insert  in  plug,  plug  in,  and  turn  clockwise  to  lock  in  place.    Attach  or  check  electrical  connection.    Refer  to applicable maintenance manual. g. Oil Coolers.  Oil cooler types and general maintenance procedures are explained in the following paragraphs. (1) Reciprocating engine oil coolers.  This oil cooler, as shown in figure 3-10, is either cylindrical or elliptical in shape.  It usually consists of a core enclosed in a double-walled shell.  The core is built of copper or aluminum tubes. Cooling air passes through the tubes while the oil flows around the outside of the tubes.  This cools the oil for return to the engine.  A bypass route is followed by the oil when the core is blocked or oil is cold. 3-13