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                            PART I - DESCRIPTIVE

           pressure system fails, the appropriate indicator will show
           cross-line and the associated gauge will indicate the
           available fuel contents.
      5.   Booster-pumps

     (a)   The booster-pumps, one in each front tank, are controlled
           by two ON/OFF switches (94) on the starboard shelf, and
           protected by two circuit breakers.  The pumps are
           designed for two-speed operation.  Normally they run
           continuously at low speed, but each at high speed is
           capable of supplying the maximum fuel demand to the
           engine.  A circuit breaker (82) for each pump is on the
           starboard shelf.
     (b)   High or low speed operation is automatically controlled
           by pressure switches.  If pressure in the pipe-lines falls
           below 8 lb./sq. in. the pumps are switched to high speed.
           When pressure rises above 12 lb./sq. in. the pumps are
           switched back to low speed.
     (c)   If one pump fails, an adjacent amber warning light (95)
           comes on and the other pump is switched to high speed.
           In such circumstances it is preferable to switch off both
           pumps and accept the feed provided by gravity and air
           pressure, unless sufficient fuel remains on the side con-
           taining the serviceable pump to complete the flight.  At
           high engine power with both pumps off, the low pressure
           warning light (59) on the starboard quarter panel may
           come on and the fuel recuperators discharge their con-
           tents.  In these circumstances no negative G manoeuvres
           should be carried out.
     (d)   A selector switch (85) and an ammeter test socket on the
           starboard shelf are provided for servicing purposes.

       6.   Flow proportioner
     (a)   From the booster-pumps fuel passes to the flow propor-
           tioner, which ensures a balanced flow from both sides of
           the fuel system under normal conditions.
     (b)   The proportioner consists of a matched pair of vane-type
           pumps, mounted on a common shaft.  Two inlet ports,
           one for each pump, accept fuel from the associated
           booster-pump.  A single exit port passes the metered fuel
           through the L.P. cock to the engine.


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