TM 1-1520-240-BD Debriefing,  Flight-Crew  -  An  interview  with  the  aircraft flight  crew  concerning  the  conditions  at  the  time  of  the combat encounter and during the returning flight for the purpose   of   acquiring   information   that   will   aid   in   the assessment of damage. Deferrable   Damage   -   Damage   whose   repair   can   be postponed,  allowing  the  aircraft  to  execute  a  one-time evacuation   flight   or   return   to   service   for   a   limited number of flight-hours. Doubler  -  Additional  layer  of  sheet  or  strip  to  reinforce structural joint. Expedient    Repair    -    A    repair    used    under    combat conditions    whose    objective    is    speed    the    return    of damaged  aircraft  to  service  (a  time-expedient  repair) and/or to salvage an aircraft that would be unrepairable by    peacetime    field    repair    standards    (a    methods- expedient  repair).    Expedient  repairs  generally  ignore peacetime repair standards concerning weight, aerodynamic  cleanliness,  and  appearance.    They  may restore  the  structure  to  less  than  original  strength,  may have   a   limited   service   life,   and   may   require   special monitoring. Failure - The state a damaged element occupies when it is no longer able to support a minimum required load for a   minimum   required   period   of   service   and/or   cannot meet the minimum required functional performance. Failure Criteria - The limits on damage of various types which,  if  exceeded,  require  an  element  to  be  classified as failed. Fairings   -   Secondary   structure   whose   function   is   to reduce drag; eg streamlined cover, or junction between two parts. Formers  -  Light  secondary  structure  added  to  maintain or improve external shape. Fuselage  Bay  -  The  structure  between  vertical  framing members  such  as  frames,  formers  and  bulkheads.    A bay   is   continuous   around   the   circumference   of   the airframe.  The frame, former or bulkhead forward of the bay is considered to belong in that bay. Gusset  -  Small  flat  member  used  to  reinforce  joints  or angles. Intercostals     -     Flat     longitudinal     structural     member (stringer)   joining   adjacent   frames   or   ribs,   usually   to support access door or equipment. Joggle  -  Small  vertical  offset  along  edge  of  sheet  or strip to allow it to overlap adjacent component. Longerons - A main longitudinal brace or support on an aircraft. Lugs - A projection or head on a metal part to serve as a cap, handle support, or fitting connection. Mounting  Bosses  -  Locally  thickened  area  to  provide support for shaft bearing, threaded connection, or other lead. Maintenance   Authority   -   The   unit   commander   or   his representative design-attomake decisions on maintenance priority for battle-damage repair. Planform  -  Geometric  shape  in  plan  esp  of  wings  and other airfoils. Proximity Relationship -     The     spatial     relationship between   elements   in   a   structure   within   and   among zones. Repair  Deferability  Assessment  -  The  process  used  to determine   if   an   airframe   containing   failed   structural members   must   be   repaired   or   can   be   safely   flown without repair, either for a one-time evacuation flight of the   aircraft   or   to   return   the   aircraft   to   service   for   a limited number of flight hours. Restricted  Operation  -  Limits  placed  on  the  use  of  a damaged aircraft during an evacuation fight. Ribs  -  Primary  structural  member  running  across  wing, or other airfoil essentially in chordwise direction. Section,  Structural  -  The  area  or  length  of  a  structural member as viewed from an endwise direction. Section  Loss  -  The  fractional  cross  sectional  area  of  a structural member removed by ballistic damage. Shear  Load  -  Load  (force)  applied  in  shear  (stress  in which  parallel  planes  of  loaded  material  tend  to  slide past each other). Skin  Panel  -  The  area  of  skin  bounded  by  longitudinal framing   members   above   and   below   and   by   vertical framing members fore and aft. Spall - A chip or fragment removed from the surface or edge  of  the  material,  usually  on  the  back  surface  of  a part that has been ballistically penetrated. Spar - Any principal structural member in airfoil running from tip to top, or from root to tip. Glossary-2