TM5-4120-376-14 Table  2-1.  OPERATOR/CREW  PREVENTIVE  MAINTENANCE  CHECKS  AND  SERVICES  (Cont) B - B e f o r e    O p e r a t i o n                         D - D u r i n g    O p e r a t i on ITEM NO. 6 7 8 9 10 11 ITEM  TO  BE INSPECTED Housing Covers Ventilation   filter Sight   indicator Noise  or  vibration Auxiliary   power receptacle   (J-12) PROCEDURE Check   for damage. Check   for damage. Check  for  dirt and   obstruction. Check   to   see that   sight   indi- cator  is  clear  of bubbles   and center   dot   green. Listen   for   any unusual  noise  or vibration. Check  for  any loose   connec- tions  or mounting. A-After   Operation EQUIPMENT  IS  NOT READY/AVAILABLE  IF: [f  dirty  or  obstructed notify    Organizational Maintenance. If   sight   indicator   has bubbles   or   yellow   color notify   Direct   Support Maintenance. If  excessive  noise  or vibration   exists   notify Organizational Maintenance. 2-7 INTERVAL B      D      A