TM 1-1520-240-BD CHAPTER 1 GENERAL INFORMATION AND ASSESSMENT SECTION I.  GENERAL 1-1. INTRODUCTION.    During  the  first  few  days  of combat    maximum    aircraft    availability    is    essential. Aircraft  will  sustain  varying  degrees  of  damage  during combat operations.  The damage must be assessed and repaired  as  quickly  as  possible.    Maximum  availability must be maintained for further sorties.  In addition to the combat   damage,   aircraft   will   have   higher   component failure   rates   because   of   increased   flying   hours   and higher    stress    levels.        Aircraft    combat    maintenance battle-damage    repair    (ACM/BDR)    is    an    operational concept   for   maintaining   aircraft   at   a   high   level   of readiness in combat. Peacetime maintenance procedures  and  methods  must  be  modified  to  achieve this.      One   method   will   be   to   defer   all   but   the   most essential  maintenance  needed  for  the  next  scheduled mission.      They   will   often   be   flown   with   nonessential components damaged, inoperative, or missing. a. Scheduled Maintenance. There are no scheduled   maintenance   and   inspections.      However, necessary lubrication, servicing; and operational checks will   not   be   deferred.      When   conditions   permit,   the “overflown"    inspections    will    be    completed.        When expedient  repairs  are  made  on  the  aircraft  or  repair  of damage  is  deferred,  to  ensure  flight  safety  or  mission accomplishment,    it    may    be    necessary    to    schedule inspections at subsequent flight hour intervals. Scheduled  battle  damage  inspections  of  this  type  will not be deferred. b. Unscheduled  Maintenance.    Repair  of  systems and    subsystems    which    are    not    critical    to    mission accomplishment,   may   be   deferred   unless   they   might cause further damage.  Items may be deferred even if it places operational limitations on the aircraft, as long as the     restricted     aircraft     can     accomplish     designated missions and can contribute to the battle.  Deferment of repairs  for  a  one-time  flight  to  a  higher  maintenance level, or for self-recovery from a combat area, is highly desirable.  This eliminates the need for another aircraft to accomplish the recovery, or the loss of the aircraft if recovery  is  not  available.    The  maintenance  officer  or assessor will make the decision based on an analysis of the overall situation and airworthiness of the aircraft. c. Assessment.  Aircraft which have battle damage will  be  inspected  and  classified  by  a  damage  assessor using   a   method   similar   to   the   medical   concept   of "triage."   Following   assessment   some   aircraft   will   be returned   to   service   immediately   through   deferment. Other   aircraft   will   be   repaired   using   approved   battle damage  repair  techniques.    Those  requiring  extensive repair  (4  to  24  hours)  will  be  set  aside  and  repaired  as manpower  and  parts  become  available.    Assessors  will be  trained  to  identify  and  assess  damage  and  failed aircraft subsystems.  They will learn isolation and repair methods and procedures and serviceability standards. 1-2. PURPOSE.     This   manual   provides   information and    instructions    for    assessing    and    repairing    battle damage  to  the  Army  CH-47D  Chinook  helicopter.    The purpose of the manual is to assist the damage assessor in   identifying   and   classifying   aircraft   battle   damage, assessing   the   extent   of   damage,   and   determining   if repair  can  be  safely  deferred.    Methods  of  expedient battle-damage repair are also presented. 1-3. SCOPE. This manual is to be used to assess and repair  battle  damage  to  the  CH-47D  helicopter.    It  is intended  for  use  by  aviation  unit  maintenance  (AVUM) and aviation intermediate maintenance (AVIM) personnel during combat operations, and for training of personnel.    The  procedures  are  to  be  used  only  during combat     operations     or     during     periods     of     extreme emergency.    The  commander  determines  when  normal maintenance procedures may be deferred.  Repairs are made   using   interim   techniques,   off-the-shelf   standard hardware  (not  necessarily  aircraft  related),  and  without concern   for   appearance.      As   new   repair   procedures, materials,  tools,  and  equipment  become  available  they will be introduced and incorporated into this manual. 1-4. FORMS.  RECORDS.  AND RFPORTS. a. Status Symbols.  Status symbols used in aircraft logbooks to record defects are defined below: (1) Red  "X".    A  red  "X"  shows  that  a  defect exists and the aircraft is unsafe for flight. (2) Circled  Red  "X".    A  red  "X"  inside  a  red circle  indicates  a  limiting  defect.    The  aircraft  may  be flown    under    specific    limits    as    directed    by    higher authority, or as directed locally until corrective action is taken. 1-1