TM   55-2840-241-23 able. h.  If  no  visual  damage  is  apparent,    engine ma   be   operationally   checked   either   in airframe  or  in  mobile    engine  test  unit.  (Refer to  Chapter  10.)  Minimum  test  time  is  30 minutes   and   shall   include   vibration   check, coastdown   noise   check,   and   post-test   mspec- tion  of  oil  falter  and  chip  detectors  for  metal, lint,   or   other      foreign   material.   Vibration levels   must   be   within   established   limits.   If   no defects   are   noted,   engine   is   considered   service- i.   If   engine   is   unserviceable,   it   will   be preserved   in   accordance   with   paragragh   3-8, returned   to   an   overhaul   facility.   Complete and   attach   necessary   tags   to   engine;   prepare necessary   forms   and   records   and   place   m records   receptacle   m   accordance   with   para- graph   3-9. 3-7.  Accident  Engine  Preservation. paced   in   a   metal   reusable   shipping   and storage    container    (paragraph    3-11),    and NOTE Do   not   treat   an   engine   for.   cor- rosion that has been involved m an accident   where   engine   failure   or malfunction is known or suspected to  have  been  a  factor.  This  engine must   be   held   for   shipment   to   an overhaul   depot   or   designated   in- investigation  area  and  should  not  be treated  for  corrosion  prevention. a.   Without   disconnecting   lines   or   fittings, make   eve   effort   to   prevent   the   remaining fuel  and  oil  in  the  engine  from  leaking  out. b.   Seal   all   openings   with   covers.   (See   fig- ure   3-2.)   If   covers   are   not   available,   seal   with barrier  material  (item  4,  table  2-2)  and  secure with   tape   (item,   table   2-2). c.   Plug   all   ports   and   cap   all   fittings.   (See f i g u r e     3 - 2 . ) d.   Install   engine   in   bottom   half   of   metal reusable   shipping   and   storage   container   in   ac- cordance   with   paragraph   3-11b.   Ground   en- gine  to  container  to  prevent  a  possible explosion   of   dangerous   vapors   which   may   be ignited   by   static   electricity   or   a   spark.   Secure all loose metal components to the container with  tape  (item  5,  table  2-2  to  prevent  pos- sible   spark   during   shipment. 3-8.   Damaged,   Cannilizd,   or   Failed   En- gine Preservation. preserve  the  compressor  as  follows: Inoperable   engines   that   are   idle   because they   require   parts   or   maintenance   shall   be preserved   in   accordance   with   paragraph   3-7b, c  and  d  and  stored  m  a  shipping  container  or  in a  clean,  dry,  area  where  the  engine  will  be  ade- quately   protected   from   dirt,   corrosion,   and p h y s i c      d a m a g e . 3-9.  Forms,  Records,  Tags  and  Stenciling. a.   The   forms,   records,   and   reports   that   are to   be   used   by   maintenance   personnel   when preparing   an   engine   or   engine   component   for storage  or  shipment  are  listed  in  and prescribed   by   DA   Pamphlet   738-751. b.   Authorized   tags   and   the   published,   proce- dure  for  their  completion  is  prescribed  in  TB 750-126.   Additional   pressurization   tags   may be  applied  to  assist  the  maintenance  officer  in depreservation. c.   Stenciling,   labeling   and   marking   of   con- tamers  for  storage  and  shipment  ares  shown  in figures   3-3   and   3-5.   Obliterate   old   markings that   do   not   apply.   Letters   and   numerals   of stencils  shall  be  in  block  letters  1/2  inch  high., Use   white   stencil   ink   (item   6,   table   2-2).   For additional   information   on   marking   and   stencil- ing   refer   to   MIL-STD-l29. 3-10.  Engine  Preservation. A  serviceable  engine  that  is  being removed from an aircraft for the purpose of storage  or  return  to  the  overhaul  facility  will be  preserved  prior  to  removal  from  the  aircraft. a.   Ensure   that   the   engine,.   accessories,   inlet duct,   plenum   chamber,   and   relet   screens   are clean   and   free   from   corrosion   and   foreign material.   When   external   cleaning   is   neces- sary,  clean  with  solvent  (item  3,  table  2-2). (Refer   to   TB   55-9150-200-24.) b.   Fill   the   engine   oil   tanks   as   necessary   to normal   operating   level   with   standard   operating oil   (item   7,   table   2-2).   Start   engine. If  avail- able,   use   external   auxiliary   power   unit   (APU). c.  Run  at  idle  to  ensure  that  the  engine  is operating   satisfactorily.   Accelerate   to   100% N2,  collective  full  down.  Operate  engine  for five   minutes   or   until   oil   temperature   reaches 88°C  (191°  F),  whichever  occurs  first. d.   Idle   engine   for   two   minutes   prior   to   shut- ting   down   engine. e.  Allow  the  engine  to  cool  until  the  com- pressor  is  cool  to  the  touch  (bare  hand);  then (1)   Disconnect   the   fuels   stem   pressure sensing  (Pc)  tube  from  the  elbow  at  the  dif- fuser   scroll.   Cap   the   tube   and   the   elbow   using compressor   protector   cleaning   kit   6886204. (2)   Disconnect   the   bleed   control   valve pressure  sensing  (Pc)  tube  from  the  elbow  at the  diffuser  scroll.  Cap  the  tube  and  the elbow   using   compressor   protector   cleaning   kit 6886204. Change 14 3-5