PART I - DESCRIPTIVE
pressure system fails, the appropriate indicator will show
cross-line and the associated gauge will indicate the
available fuel contents.
(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
(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.