MAINTENANCE AND TESTING LEARNING OBJECTIVE:    Identify main- tenance and testing procedures at the organizational and intermediate levels. The maintenance and testing responsibilities of an M61A1 gun installation are distributed evenly between the  organizational  and  intermediate  levels  of maintenance. The basic responsibilities of these two levels of maintenance are discussed in the following paragraphs. ORGANIZATIONAL MAINTENANCE Organizational maintenance includes servicing (loading and unloading), preflight, postflight, minor periodic maintenance, malfunction troubleshooting, and removal and installation of components on the aircraft. Also, maintenance of the aircraft system and controls must be included in the AO's organizational responsibilities. The gun firing record or log is kept at this level. The cumulative total of rounds fired is the basis for most of the maintenance. The number of rounds fired per firing flight is obtained from a counter located within the aircraft. For record accuracy, each time the gun installation is loaded, the counter must be reset (usually to zero) according to the instructions applicable to the aircraft. The two primary tasks that depend upon the round interval (rounds fired) are (1) torquing the two forward front track bolts (30,000 rounds), and (2) changing the breech-bolt assemblies (15,000 rounds). Organizational   responsibilities   are   not   included in NAVAIR 11-95M61A1-1 or the NAVAIR 11-95M61A1-2.   Organizational   responsibilities   are outlined in MRCs, aircraft MIMs, and aircraft loading manuals. If   a   component   is   being   removed   for   sudden stoppage (jam) maintenance, be careful and take extra precautions.  Loose  propellant  powder  from  ruptured cartridge   cases   may   be   scattered   about   the   gun compartment.   This   creates   an   extremely   hazardous situation.  The  loose  powder  must  be  removed  in  a RADHAZ-free    environment    before    you    begin    to remove a component. INTERMEDIATE MAINTENANCE Intermediate maintenance responsibilities are tasks associated with repair or replacement of unserviceable or  damaged  assemblies,  components,  or  parts  of  the gun    installation    that    do    not    require    the    special maintenance  facilities  of  an  overhaul  depot.  When  a gun reaches a round interval of 120,000 rounds fired or require   major   repair   or   alteration,   it   is   sent   to   a depot-level   maintenance   activity.   The   ammunition handling and gun drive system maintenance procedures are identical at both the intermediate- and depot-maintenance   levels   (with   one   exception,   the depot level removes bearings); therefore, such maintenance is generally performed at the intermediate level.  Intermediate  maintenance  may  be  divided  into two categories—scheduled and unscheduled. Scheduled maintenance includes inspecting, disassembling, replacing parts, lubricating, assembling,   and   functionally   checking   components based   on   the   round   interval   specified   in   technical manuals. Scheduled gun maintenance begins at 15,000 rounds and proceeds through various interval states for different  parts  replacement  up  to  the  120,000-round overhaul   interval.   Scheduled   maintenance   for   the handling and drive system is set at an interval of 30,000 rounds. REVIEW NUMBER 6 Q1. The breech bolts are changed out when what number  of  rounds  have  been  fired  from  the M61A1 gun system? Q2. What is the overhaul interval for the M61A1 gun? Q3. At   what   interval   should   scheduled   main- tenance for the handling and drive system be done? SAFETY PRECAUTIONS LEARNING OBJECTIVE: Identify safety pre- cautions   to   follow   when   working   with   the M61A1 gun. The weapons systems described in this chapter are safe  systems.  Live  rounds  are  isolated  from  the  firing circuits  except  when  the  gun  system  is  deliberately being  fired.  The  gun  system  is  RADHAZ  safe  and completely  shielded  from  radiation  fields.  The  gun  is charged and cleared in flight, so the aircraft can take off and  land  without  live  rounds  in  the  firing  position. Although the sole purpose of all ordnance is to destroy an  enemy,  the  equipment  cannot  identify  friend  from foe. Therefore, all safety precautions must be followed at all times. The  following  general  safety  precautions  are  not related to any specific equipment or procedure. These 6-18