TM 1-1500-204-23-3 (k)    Allow  repair  to  remain  undisturbed for at least 8 hours.  The fuel cell should not be returned to service for 24 hours. (I)    Visually inspect repair for workmanship,  no  loose  edges,  no  voids,  and  adhesive fully cured. (3) Internal  and  External  Loose  Seams  (Lap or Splice, Edge, or Fitting Flange) Seams With Up to 2 Sq.  Inches of Material Missing Fitting Flanges With 1/4 to 1/2 Inch of Material Missing/Damaged. WARNING Acetone  and  repair  adhesives  are flammable  and  toxic.    Keep  away from heat, sparks and open flame. Wear  safety  glasses,  gloves  and protective     clothing     to     prevent contact.  Wear a NIOSH approved air-purifying respirator for organic vapors and work in a well ventilated area.  If contact occurs, flush   areas   with   water   and   get medical   attention.      If   ingestion occurs   get   medical   attention   at once. (a)    If   part   of   the   seam   is   loose,   first perform procedure in paragraphs (a) through (j) Internal and   External   Loose   Seam   (Lap   or   Splice,   Edge,   or Fitting Flange), With Up to 1/4 Inch of Material Missing or  Damaged.    Allow  repair  to  dry  at  least  60  minutes before proceeding to step (b) below. (b)    Cut   a   patch   from   repair   material (item 19, table 2-11 for interior repair, item 25, table 2- 11    for    exterior    repair).        The    patch    shall    overlap damaged area (from outer edge of damaged area) 1 1/2 inches  in  all  directions.    If  possible  the  patch  shall  be round.      If   a   round   patch   is   not   feasible,   an   oval   or square/rectangular   patch   with   round   comers   shall   be used. (c)    Clean surface of fuel cell 1/4 to 1/2 inch larger in all directions where patch is to be applied. Use a piece of dean cheesecloth (item 16, table 2-11 ) dampened   with   acetone   (item   3,   table   2-11).      Wear gloves (item 4, table 2-11). (d)    Lightly,   hand   buff   surface   of   fuel cell  using  emery  cloth  (120  grit)  (item  17,  table  2-11). Buff entire fuel cell surface cleaned in step (c) above. (e)    Clean  buffed  area.    Use  a  piece  of clean cheesecloth (item 16, table 2-11) dampened with acetone (item 3, table 2-11).  Wear gloves (item 4, table 2-11).    The  surface  must  be  clean  and  dry  in  order  to apply repair patch. (f)    Lightly,   hand   buff   gum   side   (side with dull finish) of patch with emery cloth (120grit) (item 17,  table  2-11).    Remove  buffing  dust  by  wiping  patch with  cheesecloth  (item  16,  table  2-11)  dampened  with acetone (item 3, table 2-11).  Wear gloves (item 4, table 2-11). WARNING Repair adhesive is flammable and should   be   kept   away   from   any ignition source. NOTE Adhesive materials should be kept tightly sealed in individual containers in a cool, dry place. (g)    Refer to paragraph c(1)(e) for mixing instructions. NOTE Do not apply adhesive beyond buffed areas. NOTE The    adhesive    should    be    used sparingly.        Two    (2)    thin,    even coats will provide better adhesion than   two   thick,   puddled   coats. Acetone  is  used  as  a  solvent  for the adhesive and, when the cemented  surface  appears  dry  to touch,   it   may   be   freshened   or made  tacky  again  by  application of this solvent. (h)    Apply   one   coat   of   adhesive   (item 18,   table   2-11   )   to   buffed   side   of   patch   and   cell innerliner and allow to dry 20-60 minutes. 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. Change 2  2-60