TM 1-1500-204-23-3 NOTE To determine if adhesive is tacky, test    it    by    pressing    a    knuckle gently against the cemented surface    and    withdrawing    it    (if practical).      Proper   tackiness   is achieved  when  a  few  threads  of adhesive    stick    to    the    knuckle. This  procedure  is  referred  to  as the knuckle test. (f)    Apply   a   second   coat   of   adhesive (item 18, table 2-11) to buffed areas of hanger and cell, allow  to  dry  until  tacky.    Adhesive  can  become  tacky within 2 to 4 minutes, depending on ambient temperature and humidity.  Perform knuckle test. NOTE If adhesive dry times are exceeded,    reapplication    of    one coat   of   adhesive   may   be   done only once (total of three coats).  if dry time is again exceeded, remove    adhesive    from    applied area using, acetone and/or buffing with emery cloth (120 grit minimum). (g)    If  necessary  to  restore  tack  to  the cemented  surfaces,  use  a  piece  of  dean  cheesecloth (item  16,  table  2-11)  dampened  with  acetone  (item  3, table  2-11),  lightly  wipe  over  cemented  areas.    Allow solvent to evaporate 10 to 20 seconds or until cemented areas become 'tacky." (h)    With   a   one-inch   or   smaller   roller (item  20,  table  2-11),  roll  over  hanger/loop  to  remove any trapped air. (i)    Allow  repair  to  remain  undisturbed for at least 8 hours.  The fuel cell should not be returned to service for 24 hours. (j)    Visually inspect repair for workmanship,  no  loose  edges,  no  voids,  and  adhesive fully cured.  If there is a defect in repair, recement per above procedure. (8) Fitting Rework (a)    Fittings    having    surface    corrosion and/or     scratches,     within     allowable     limits,     can     be reworked in accordance with the following procedures. WARNING Wear     rubber     gloves     and     eye protection throughout fitting rework   procedure,   except   when using emery cloth and Scotchbrite pad. (b)    Rework fitting as follows: 1 If there is a heavy accumulation of grease,  oil  or  dirt,  or  if  the  metal  is  severely  corroded, dean with a piece of dean cheesecloth (item 16, table 2- 11)   dampened   with   acetone   (item   3,   table   2-11).      If acetone  does  not  completely  clean  fitting  or  acetone beads  up,  clean  fitting  with  a  commercial  cleaner  (i.e. Ajax) (item 26, table 2-11). 2 After cleaning, wipe or rinse cleaning  agent(s)  from  fuel  cell  fitting  and  surrounding area with water. 3 Immediately  prior  to  rework,  wipe all  contaminants  from  the  fitting  using  a  clean  piece  of cheesecloth    (item    16,    table    2-11)    dampened    with acetone (item 3, table 2-11). CAUTION Metal applicators, cleaning devices  or  materials  shall  not  be used  under  any  circumstances  in this procedure. 4 If metal is severely corroded and/or  there  are  scratches  or  gouges,  buff  with  emery cloth (120 grit) (item 17, table 2-11) until surface is free of corrosion, scratches and/or gouges. 5 Using   fine   emery   cloth   (300   grit) (item   13,   table   2-11),   sand/polish   surface   previously buffed  with  120  grit  emery  cloth  (item  17,  table  2-11) until surface is smooth and free of buffing scratches. 6 Remove any exposed surface corrosion which lies above the normal metal surface or which   appears   loose   or   powdery   by   rubbing   with   a Scotchbrite pad (item 12, table 2-11). 7 Wipe  off  residue  with  a  piece  of dean  cheesecloth  (item  16,  table  2-11)  dampened  with acetone (item 3, table 2-11). Change 2  2-65