TM 55-1930-209-14&P-19 Table 9-3.  Preventive Maintenance Checks and Services for Electrical Power Systems(Continued) B -  Before D -  During A -  After H -  Hourly Interval INTERVAL ITEM PROCEDURES EQUIPMENT ITEM TO BE CHECK FOR AND HAVE IS NOT READY/ NO. INSPECTED REPAIRED OR ADJUSTED AVAILABLE IF B   D   A H AS NECESSARY 12 400 hrs NOTE Every 400 hours of operation or every 12 months (whichever comes first). a.     Redtag SAG on switchboard panel indi- cation, "WARNING-DO NOT ACTI- VATE- REPAIRS BEING MADE." b.     Check hoses and clamps.  Replace hoses if there is any evidence of deterioration to hose material.  Tighten clamps as neces- sary. 13 400 hrs Fuel Lift Pump a.     Notify Direct Support maintenance to Chamberclean the fuel lift pump chamber: 1) Remove the fuel lift pump cover and pulsator diaphragm by unscrewing and removing the cover screw. 2) Clean the sediment chamber and check the pulsator diaphragm for con- dition.  Replace if necessary. 3) Refit the pulsator diaphragm and cover.  Tighten the securing screw just sufficiently to make a tight sealing joint. 4) Vent and bleed the fuel system as fol- lows: CAUTION Air must be vented from the fuel system whenever any part of the system between the fuel tank and injection pump has been disconnected for any reason or if the system has been emptied of fuel. (a) Unscrew by two or three turns, the vent plug on top of the fuel filter cover (not the return pipe to the tank).  Later type fuel filters are self venting and do not have a vent plug.  Air vent the fuel filter by removing the excess fuel return pipe, to the fuel tank, from the fil- ter head.  Operate the fuel feed pump priming lever until diesel fuel, free from air bubbles, issues from the nonreturn valve.  Refit fuel return pipe. 9-41