TM   55-4920-402-13&P APPENDIX   B MAINTENANCE   ALLOCATION   CHART Section   I. INTRODUCTION B-1.   Maintenance   Allocation   Chart. a.  This  Maintenance  Allocation  Chart  (MAC)  assigns maintenance  functions  in  accordance  with  the  Three Levels  of  Maintenance  concept  for  army  aircraft.  These maintenance    levels: Aviation   Unit   Maintenance (AVUM), Aviation Intermediate Maintenance (AVIM) and Depot Maintenance are depicted on the MAC as: AVUM  which  corresponds  to  the  O  code  in  the Repair Parts and Special Tools List (RPSTL). AVIM which corresponds to the F code in the Repair Parts and Special Tools List (RPSTL). Depot which corresponds to the D code in the Repair Parts and Special Tools List (RPSTL). b. The maintenance to be performed below depot and in the field is described as follows: (1) Aviation Unit Maintenance (AVUM).  AVUM ac- tivities will be staffed and equipped to perform high fre- quency  “On-Equipment”  maintenance  tasks  required  to retain or return equipment to a serviceable condition. The  maintenance  capability  of  the  AVUM  will  be governed by the MAC and limited by the amount and complexity  of  support  equipment,  facilities  required, and number of spaces and critical skills available. The range and quantity of authorized spare modules/com- ponents  will  be  consistent  with  the  mobility  re- quirements  dictated  by  the  air  mobility  concept. [Assignment of maintenance tasks to divisional com- pany   size   aviation   units   will   consider   the   overall maintenance  capability  of  the  division,  the  requirement to conserve personnel and equipment resources and air mobility  requirements). (a) Company Size Aviation Units.  Perform those tasks   which   consist   primarily   of   preventive maintenance and maintenance repair and replacement functions  associated  with  sustaining  a  high  level  of equipment  operational  readiness.  Perform  maintenance inspections and servicing to include daily, intermediate, periodic and special inspections as authorized by the MAC  or  higher  headquarters.  Identify  the  cause  of equipment/system malfunctions using applicable technical  manual  troubleshooting  instructions,  Built-In- Test Equipment (BITE), installed instruments, or easy to  use  Test  Measurement  and  Diagnostic  Equipment (TMDE).   Replace   worn   or   damaged   modules/com- ponents which do not require complex adjustments or system alignment and which can be removed/installed with  available  skills,  tools  and  equipment.  Perform operational  and  continuity  checks  and  make  minor repairs.  Perform  servicing,  functional  adjustments,  and minor    repair/replacement. Evacuate    unserviceable modules/components and end items beyond the repair capability of AVUM to the supporting AVIM. (b) Less than Company Size Aviation Units.  Avia- tion  elements  organic  to  brigade,  group,  battalion  head- quarters and detachment size units are normally small and have less than ten aircraft assigned. Maintenance tasks performed by the aircraft crew chief or assigned aircraft repairman will normally be limited to preven- tive maintenance inspections, servicing, spot painting, spot  drilling,  minor  adjustments,  module/component fault   diagnosis and    replacement of   selected modules/components. Repair functions will normally be accomplished by the supporting AVIM unit. (2)   Aviation   Intermediate   Maintenance   (AVIM). AVIM   provides   mobile,   responsive   “One   Stop” maintenance  support.  (Maintenance  functions  which  are not conducive to sustaining air mobility will be assigned to depot maintenance.) Performs all maintenance func- tions authorized to be done at AVUM. Repair of equip- ment for return to user will emphasize support or opera- tional  readiness  requirements.  Authorized  maintenance includes   replacement   and   repair   of   modules/com- ponents and end items which can be accomplished effi- ciently  with  available  skills,  tools,  and  equipment. Establishes  the  Direct  Exchange  (DX)  program  for AVUM units by repairing selected items for return to stock when such repairs cannot be accomplished at the AVUM level. Inspects, troubleshoots, tests, diagnoses, repairs, adjusts, calibrates, and  aligns system modules/components.   Module/component   disassembly and repair will support the DX program and will normal- ly be limited to tasks requiring cleaning and the replace- ment of seals, fittings and items of common hardware. Unserviceable reparable modules/components and end items which are beyond the capability of AVIM to repair will be evacuated to Depot Maintenance. This level will perform   special   inspections   which   exceed   AVUM capability. Provides quick response maintenance sup- port, on-the-job-training, and   technical   assistance through the use of mobile maintenance contact teams. Maintenance  authorized  operational  readiness  float. Provides   collections   and   classification   services   for B-1