PART I-DESCRIPTIVE
A.L.1 (b) H.P. fuel pumps
Page 13 Two engine-driven pumps are housed in a single casing but are sepa-
rated from each other. A single overspeed governor controls the
maximum speed of both pumps, and a single servo control system
connects both pumps to the B.P.C. and A.C.U.
(c) H.P. pump isolating valve and warning light (when fitted)
(i) The isolating valve is intended as a means of restoring power
in flight in the event of a failure of the H.P. pumps servo
system causing a sudden loss of power. (See para. 76(a).)
(ii) The valve is controlled by an ONE-OFF switch on the port
wall, forward of item (18). When the switch is set ON one
H.P. pump is cut off from the servo system, which continues
to control only the other H.P. pump. The isolated pump
moves to full stroke and is controlled only by its over-speed
governor.
(iii) A magnetic indicator on the port instrument panel, shows
white when the isolating valve is closed and black with the
valve switched off.
(d) H.P. fuel cock control
(i) The H.P. fuel cock lever (2) on the port shelf controls the
fuel flow to the pressurising valve and burners. It should be
moved down (off) to stop the engine. A catch on the control
holds it in the open position.
(ii) A relight pushbutton is on the inboard side of the H.P. cock
lever.
(e) Oil system
Oil is carried in the engine sump. the capacity of which is 17 pints.
One pressure and four scavenge pumps maintain a continuous
circulation through a cooler and filter to the engine bearings and
gears. An oil pressure gauge is on the starboard side of the instru-
ment panel.
7. Engine starting system
(a) Starting is by a triple-breech turbo-starter, using one cartridge for
each start.
(b) (i) The STARTER MASTER switch (33) completes the circuit
to the STARTER button (see para. 7 (b) (ii)). When the
starter button is pressed, with the IGNITION switch (32) on,
the circuit to the igniter plugs is completed. Both the master
and ignition switches should be on for starting and at all
times when the engine is running.
(ii) When Mod. 571 is incorporated a circuit breaker is introduced
into the ignition circuit and is fitted at the aft end of the
port shelf. It must be in for starting and at a11 times when the
engine is running.
(c) When the guarded STARTER button (65) is pressed it is held in
the depressed position by a solenoid and the automatic starting
cycle is then initiated. the cartridge firing over a period of 2-3
seconds. The engine should accelerate up to normal idling r.p.m.
of 2,750 ± 100 in approximately 30 seconds. 13
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