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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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