TM 1-1520-240-BD a. Initial  Assessment.      Refer  to  Table  2-1.    To perform   an   initial   assessment,   the   assessor   must   be acquainted    with    structural    damage    modes    and    the primary structure.  He shall be capable of differentiating between primary and secondary structure, and he must understand  the  function  of  primary  structural  elements. The initial assessment consists of a visual inspection of primary   structure.      The   assessor   determines   if   any primary caps, webs, or panels are damaged or fractured and decides whether- (1)  The damage appears to be deferrable; (2)  A detailed assessment can be made and the damage can be repaired by BDAR techniques within the time  available  to  return  the  aircraft  to  service  in  the ongoing battle; (3)    An  adequate  assessment  can  be  made  and the  damage  can  be  repaired  by  BDAR  techniques  to enable the aircraft to self-recover; (4)  A detailed assessment cannot be made or the damage cannot be repaired by BDAR techniques within the available time; or (5)  The aircraft is damaged beyond repair, and its disposition shall be arranged (e.g., recovery, cannibalization, or destruction). b. Detailed Assessment. (1)     Access  to  Damaged  Structure.    Locate  all damage to airframe primary structure.  Remove access panels,   covers,   and   fairings   in   the   damaged   area. Remove aircraft components as required to inspect the structure.  Use the location of entrance and exit wounds and  the  estimates  of  projectile  paths  to  determine  the areas  where  damage  may  be  present  and  access  to interior inspection will be needed.  If an area of structure suspected   of   being   damaged   cannot   be   reached   by other  means,  cut  small  inspection  holes  in  the  exterior skin.  Then inspect internal members with an inspection light and mirror. NOTE Inspection  holes  cut  in  the  exterior skin if left unrepaired will have to be treated  as  damaged  structure  in  the damage evaluation.  Allow for access to  the  areas  immediately  next  to  the area where damage is known to have occurred.        This    will    ensure    that damage   caused   by   stray   particles and   dislodged   sections   of   material can be found.  All significant damage to    the    airframe    primary    structure must be located.  Small damage can be critical to some components. (2)  Inspecting for Cracks. (a)  Impact Cracks.  Cracks may be caused by  projectile  impact  or  penetration.    They  may  also  be caused   as   a   direct   result   of   blast   pressures.      Battle damaged   elements   carrying   reduced   loads   will   place more severe loads on surviving members and may also produce cracks.  When cracks are a result of these last two  factors,  they  may  occur  in  regions  away  from  the size of the primary damage. (b)  Projectile Damage Site Cracks.  Cracks will   primarily   be   found   at   the   site   of   the   projectile damage.  Holes, spalls, and gouges caused by ricochets and embedded particles will often have cracks associated  with  them.    These  may  be  large  and  visible or hairline microscopic.  Small cracks may be as critical as  large  cracks  because  then  may  grow  rapidly  under continued loading, particularly when located at the edge of a hole. (c)   Airframe  Structure  Cracks.    Locate  all cracks  in  airframe  primary  structure.    At  each  damage site,  inspect  the  area  for  cracks.    Use  inspection  aids such  as  magnifying  glasses  or  dye  penetrant  to  locate small cracks.  Cracks may not go all the way through the material, so it is necessary to inspect both sides.  When a   structure   shows   signs   of   overstress,   it   is   vital   to inspect for cracks around fasteners. (d)     High    Explosive    Incendiary    (HIFI) Explosion  Cracks.      For   aircraft   damaged   by   an   HEI strike,   inspect   all   of   the   structure   in   the   area   of   the explosion.    Aircraft  may  have  been  flown  with  major structural battle damage or failure.  It is vital to inspect for cracks in all areas to which additional load may have been distributed. 2-5