2-1 TM   55-4920-400-13 CHAPTER 2 OPERATING INSTRUCTIONS Section I. 2-1.  General.  This  chapter for  utilizing  the  test  set  to ments.  which  operate  within SERVICE UPON contains  procedures test  aircraft  instru- the  equivalent  pres- sure and vacum ranges which are simulated by the test set. A safety relief protection system is incorpo- rated in the test set to protect both the instruments of the test set and the instrument under test. If ex- cessive pressure or vacuum is applied to the instru- ments,   the   over-load   protection   system   auto- maltically operates solenoid valves which close the pressur and vacuum lines to prevent damage to the instruments. 2-2.  Unloading  and  Uncrating. CAUTION Handle the tester with care as the del- icate instruments it incorporates can easily be damaged by shock. a. Cut  the  steel  bands  and  remove  the  top  and front of the wooden crate. b. Slide the inner carton out of the crate and re- move the vapor barrier from the carton. c. Open  the  carton  and  remove  the  desiccants and  sheet  of  cardboard  before  removing  the  tester from the carton. Section II. CONTROLS 2-5.  General.  This  section  describes,  locates,  il- lustr:ates and furnishes the operator with sufficient information  pertaining  to  the  various  controls  and instrurments  provided  for  the  proper  operation  of  the equipment. 2-6.   Power   Switch.   The   double   pole,   double throw, toggle-type power switch, has an OFF posi- tion  which  opens  the  circuit  and  shuts  off  the  elec- trical power supply to the tester. The ON position is in  the  circuit  to  provide  electrical  current  to  the tester when the power source is connected. 2-7.   Indicator   Light.   The  indicator  light  illu- minates  when  the  power  circuit  in  the  tester  is operating. RECEIPT OF EQUIPMENT d. Save  packaging  material  when  future  use  is anticipated. 2-3. Inspection of New/Used Equipment.  Make a  thorough,  visual  inspection  of  the  tester  for  de- fects and missing parts (paras.  a through c below), repairing  if  possible.  If  necessary,  authorized  per- sonnel  should  fill  out  DD  Form  6  (Packaging  and Improvement Report) to report damage loss, or im- proper shipment of equipment. a. Unlatch and remove all covers, remove the ac- cessories and check for defective or missing parts. b.  Inspect   the   controls   and   instruments   for proper operation, defects and evidence of leakage. c. Release  the  fasteners  to  open  the  rear  access panel  and  inspect  for  defects,  evidence  of  leakage, and the operation of the reservoir selector valve. d. Perform  the  inspections  specified  in  the  be- fore   operation   services   of   the   operator’s   daily service. 2-4.  Servicing  New/Used  Equipment.  Perform the  following  services  before  operating  the  tester. a.  Lubricate   in   accordance   with   instructions contained in figure 2-1. b. Perform the before operation services listed in the operator’s daily service. AND  INSTRUMENTS 2-8. Cartridge Fuse.  The 28 vdc, 4-amp cartridge fuse provides protection against an excessive flow of current which would damage the electrical system. 2-9.  Vacuum  Selector  Knob.  The  VACUUM  se- lector knob has three positions, and operates a valve which  functions  as  a  single  control  manifold  and provides various vacuum-pressure systems required to  test  aircraft  instruments  (manifold  pressure). 2-10.  Pressure  Selector  Knob.  The  PRESSURE selector knob has five positions and operates a valve which  functions  as  a  single  control  manifold  and provides   various   vacuum,   pressure,   and   vacum- pressure  systems  required  to  test  and/or  calibrate certain  types  of  aircraft  instruments.