TM 1-1510-218-10 2-54 CAUTION Engine   operation   using   only   the   engine- driven  primary  (high-pressure)  fuel  pump without    standby    fuel    pump    or    engine- driven boost pump fuel pressure is limited to  10  cumulative  hours.    This  condition  is indicated by illumination of either #1 or #2 FUEL PRESS lights on the warning annunciator panel and simultaneous illumination of the master warning light on the  glare  shield.    Refer  to  Chapter  9.    All time  in  this  category  shall  be  entered  on DA   Form   2408-13-1   for   the   attention   of maintenance personnel. a.   Fuel Tanks.  The main wing tanks consist of two leading edge tanks, two box section bladder tanks, and  an  integral  (wet  cell)  tank  all  interconnected  to flow  into  the  nacelle  tank  by  gravity.    This  system  of tanks is filled from the filler located near the wing tip.   The auxiliary fuel system consists of a center section tank,  located  in  the  inboard  wing,  with  its  own  filler opening   and   an   automatic   fuel   transfer   system   to transfer the fuel into the nacelle tank.  An anti-siphon valve  is  installed  at  each  filler  port  to  prevent  loss  of fuel  or  collapse  of  a  fuel  cell  bladder  in  the  event  of improper securing or loss of the filler cap.  The nacelle tank is located directly behind the engine and contains a submerged, electrically operated standby fuel pump.   The  fuel  from  the  nacelle  tank  is  fed  directly  into  the engine  by  either  the  engine-driven primary fuel pump or, as backup, the standby fuel pump.  The quantity of fuel for the tanks is detailed in Table 2-3. b.  Engine Driven Boost Pumps.  A gear-driven boost  pump  mounted  on  each  engine  supplies  fuel, under pressure, from the nacelle tank to the inlet of the engine-driven  primary  high-pressure  pump  for  engine starting  and  all  normal  operations.    Either  the  engine- driven boost pump or stand by fuel pump is capable of supplying    sufficient    pressure    to    the    engine-driven primary high-pressure pump and thus maintain normal engine operation. c.   Standby     Fuel     Pumps.           A     submerged, electrically operated standby fuel pump, located within each   nacelle  tank,  serves  as  a  backup  unit  for  the engine-driven  boost  pump.    The  standby  pumps  are switched   off   during   normal   system   operations.      A standby fuel pump will be operated during crossfeed to pump  fuel  from  one  system  to  the  other.   The correct pump is automatically selected when the CROSSFEED  switch  is  activated.    Each  standby  fuel pump   has   an   inertia   switch   included   in   the   power supply  circuit.    When  subjected  to  a  5  to  6  G  shock loading, as in a crash situation, the inertia switch will remove  electrical  power  from  the  standby  fuel  pump.   The   standby   fuel   pumps   are   protected   by   two   10- ampere circuit breakers, placarded  STANDBY PUMP 1 or  2, located on the overhead circuit breaker panel, and  four  5-ampere circuit breakers wired (two each in parallel) on the hot battery bus. Table 2-3.  Fuel Quantity Data TANKS NUMBER GALLONS **POUNDS Wing tanks   5 136    924.8 Nacelle tank   1    57    387.6 Auxiliary tank   1    79    537.2 LEFT ENGINE (Ferry tank) *** (1) (120)   (816.0) Wing tanks   5 136    924.8 Nacelle tank   1    57    387.6 Auxiliary tank   1    79    537.2 RIGHT ENGINE (Ferry tank) *** (1) (120)   (816.0) *TOTALS 14 544 3699.2 *(TOTALS with Ferry tanks installed) (16) (784) (5331.2) *     Unusable fuel quantity and weight (4 gallons, 26 pounds not included in totals). **     Fuel weight is based on standard day conditions at 6.8 pounds per U.S. gallon.  Total fuel system capacity, without ferry fuel, is 548 gallons. ***     Data for ferry tanks is included when they are installed.