TM 1-1500-204-23-3 CAUTION Protect  fuel  cell  at  all  times  from sharp  objects  and  from  extremes of temperature and humidity. CAUTION Crashworthy, self-sealing fuel cells   shall   not   be   folded   and/or collapsed    for    periods    of    more than   four   (4)   hours.      Fuel   cells must  be  supported  when  stored, shipped, and/or repaired. CAUTION Preservation of a fuel cell shall be delayed until repair work is completed,  unless  it  will  be  more than   30   days   before   repairs   are started.  This reduces the cleanup effort by repair personnel prior to making repairs. Refer to paragraph 2-5f (5) for preservation procedure. NOTE The  following  repair  criteria  and procedures  apply  to  self-sealing, crash resistant fuel cells. (1) Classify    fuel    cell    damage    as    follows: Minor damage.  See table 2-5 for serviceable limits. (2) Reparable damage is classified as follows: (a)    Internal            Blister            Damage. Blisters  exceeding  1/4  inch  diameter  must  be  repaired. Cut  blister(s)  open,  remove  fluid  in  blister,  dean,  buff, dean, cement loose blister material down, and apply an internal patch. (b)    Internal  and  External  Loose  Seam (Lap    or    Splice,    Edge,    or    Fitting    Flange)    Damage. Refers to loose edge of lap splice, reinforcement ply, or fitting   flange.      All   loose   seams/edges   of   lap   splices, reinforcement plies, or fitting flanges (exposed edge on interior or exterior surface of cell) with up to 1/4 inch of material    missing    can    be    cleaned,    buffed,    cleaned, cemented and the repair rolled with a roller.  For seams and   splices   with   up   to   2   square   inches   of   material missing  or  fitting  flanges  with  1/4  inch  minimum  to  1/2 inch     maximum     of     material     missing     or     otherwise damaged, a patch repair is required. (c)    Cuts,    Tears,    Chafing,    Scuffs    or Snag Damage.  All cuts, tears, chafing, scuffs or snags occurring to the innerliner or outerply, where the coating is missing or cord/fabric is exposed but not tom, can be buffed  and  cemented,  and  allowed  to  air  dry  8  hours. All  cuts,  tears,  chafing,  scuffs,  or  snags,  less  than  2 inches   in   length   or   area,   occurring   to   the   innerliner, where fabric is torn/cut require an internal patch repair. (d)    Hole   or   Cut   1/8   Inch   or   Less   in Diameter  in  External  Surface  or  Penetrating  the  Entire Cell Wall.  No sealant activation is allowed. (e)    Loose     or     Separated     Hanger     or Loop.      Loose   or   separated   hangers   or   loops   can   be cleaned, buffed, cleaned, and cemented back in place. (f)    Replacement of Fitting Thread Inserts (Helicoils).  CTM 1-1500-204-23-6). (g)    Fitting     Damage/Finish.          Fittings which    have    inter-crystalline    corrosion    or    scratches, outside of the critical sealing surface, to a depth of .030 inch can be reworked. b. Non-Repairable  Damage.    Damage  that  is  not reparable is classified as follows: (1) Damage    which    extends    into    a    comer (three plane). (2) Damage which has led to activation of the sealant ply/plies. (3) Cuts or tears longer than 2 inches and any damaged area larger than 2 square inches. (4) A  hole  larger  than  1/8  inch  in  diameter which penetrates the entire cell wall (through hole). (5) A    hole    which    penetrates    beyond    the exterior surface ply larger than 1/8 inch in diameter. (6) External blister damage. (7) Damage    to    fitting    O-ring    groove    and damage   inside   of   the   critical   sealing   surface.      Also, damage  within  1/4  inch  of  O-ring  grooves,  bolt  holes, etc.    inside  or  outside  of  critical  sealing  surface  is  not reparable. Change 2  2-56