ports  inside  the  MFC.  These  pressure  ports  direct  the fuel  flow  to  the  vane  actuators  via  tubing. This  timing  is  accomplished  by  pumping  the  vanes to  the  full  open  position  and  maintaining  100  to  200  psig on  the  system.  At  the  same  time,  be  sure  you  check  to see  if  the  bottom  of  the  rig  plates  are  parallel  with  each other.   NEVER  relax  the  pressure  on  the  system  while performing   the   rig   plate   check.   If   the   pressure   is relaxed,  the  feedback  lever  may  drift  and  the  rig  will  be incorrect. When  the  system  is  full  open,  and  100  psig  is applied,  try  to  move  the  bolt  back  and  forth  on  the forward  end  of  the  cable  at  the  bellcrank.  If  the  bolt cannot   be   moved,   it   most   likely   indicates   a   binding   at the  front  section  of  the  cable  assembly.  Of  course,  this “assumes”  that  the  bolt  is  of  the  correct  diameter  and  is normally  free  to  move.  If  the  bolt  cannot  be  moved  back and   forth,   reverse   the   pump   selector   handle   to   the   RE (rod  end)  position.  You  then  need  to  apply  a  few  strokes to  move  the  vanes  slightly  towards  the  closed  position. If  the  bolt  becomes  free  to  move,  the  forward  section  of the   cable   assembly   is   definitely   binding.   Binding   is easily  connected  by  loosening  the  jamnut  on  the  forward rod  end  bearing  and  rotating  the  rod  end  bearing  a  half turn  at  a  time.  This  adjustment  shortens  the  distance (right-hand   rotation)   and   usually   solves   the   problem. Reinstall  and  recheck  the  rigging.  If  the  rigging  is  still slightly  off,  use  the  trimmer  bracket  adjustment  to  make the  correction. The   bottom   line What  are  you  really  trying  to  accomplish?  Look  at it   this   way.   The   system   is   pumped   full   open,   and   the piston   inside   each   actuator   is   physically   bottomed   out. This  in  turn  fixes  the  position  of  the  bellcrank  bolt  hole when   a   minimum   of   100   psig   is   maintained.   If   you manually  hold  the  feedback  lever  arm  in  order  to  match the  bottom  of  the  rig  plates,  the  plates  become  parallel to  each  other.  The  two  fixed  ends  now  have  a  fixed distance   between   them.   By   adjusting   the   length   of   the cable  assembly,  you  will  maintain  a  proper  fit  between the  two  fixed  points. You   have   now   successfully   accomplished   a   VSV feedback   cable   rigging.   You   were   able   to   do   so   by   a combination   of   adjusting   the   fore   and   aft   rod   end bearings  within  the  limitations  and  following  the published  trimmer  bracket  instructions. VSV  SCHEDULING VSV  scheduling  is  verified  by  using  the  variable vane protractor (1C5714). You must check the protractor  for  accuracy  before  every  use  on  the  engine. The  check  will  detect  any  inaccuracies  due  to  damage, wear,   and   so   forth.   Use   the   protractor   setmaster (9441M67G01)   to   accomplish   this   test.   The   protractor is  installed  on  the  master  vane  located  at  the  9  o’clock split  line,  aft  looking  forward. CAUTION Do  not  check  the  vane  angle  if  idle  speed is  less  than  4,900  rpm,  or  greater  than  5,000 rpm.  Before  adjusting  the  idle  rpm  screw  on the   MFC,   assure   PLA   mechanical   and electrical  rigging  is  connect. Once  the  protractor’s  accuracy  has  been  verified, you  are  now  ready  to  install  the  protractor  on  the  engine. Install  the  protractor  locator  on  the  engine  and  ensure  it mounts  correctly  (it  will  only  goon  one  way  correctly). If  installed  incorrectly,  the  shaft  cannot  be  threaded on  the  vane  stud.  If  the  locator  is  wiggled  around  so  that the  shaft  can  be  threaded  on  the  vane  stud,  it  will  be cocked,  but  the  protractor  can  still  be  installed  over  the locator.  However,  the  vane  angle  is  now  4°  too  far  open. If  the  protractor  is  left  in  this  position,  the  angle  will be  4°  more  open  when  checked  at  idle  rpm  than  when compared   to   the   table. This   means   a   perfectly serviceable  engine  could  be  rejected  because  it  failed  the angle   check.   When   installed   correctly,   the   locator   is flush  to  the  lever  and,  at  the  same  time,  the  shaft  can  be threaded  on  the  vane  stud  without  wiggling  it  around. GAS  TURBINE  PRESERVATION  AND CORROSION   CONTROL Modern  gas  turbines  and  their  support  equipment are   dependent   upon   the   structural   soundness   of   the metals   from   which   they   are   fabricated.   The   greatest threat   to   the   structural   integrity   of   this   equipment   is metal   corrosion.   With   the   higher   demands   being   made on  these  metals,  both  in  strength  and  in  closer  tolerances, this  equipment  would  rapidly  deteriorate  and  become inoperative control. without   regular   attention   to   corrosion 2-33