PART 1 - DESCRIPTIVE
          
                control (42) on the instrument panel, is pulled, after first
                pressing in the central knob, the air is directed to the
                lowering jacks.  The available pressure is shown on a
                gauge(7)at the aft end of the port shelf.

          33.   Airbrake control
                              
          (a)   An under-fuselage airbrake is provided, which is
                electrically selected and hydraulically operated.  It will
                extend fully at any speed.
          
          (b)  Control of the airbrake is by means of a three-position
               switch (29), spring-loaded to the central off position, on
               the throttle lever.  No position other than fully in or fully
               out can be selected.  A magnetic indicator (39) on the
               instrument panel shows black only when the airbrake is
               fully in.
               
          (c)  The airbrake is automatically inoperative when the under-
               carriage is lowered.  If the undercarriage is lowered when
               the airbrake is out, the airbrake will automatically
               retract.  Airbrake IN must not normally be obtained by
               selecting undercarriage down.

          (d)  A spring-loaded switch (13) on the port wall enables the
               airbrake to be tested on the ground.  When the switch is
               held to TEST the airbrake extends through 10° only and
               then retracts with a slight bump.  The indicator shows
               white momentarily when the airbrake is out.
                              

          34.   Wheel brakes control

          (a)   The wheel brakes are operated hydraulically by means of
                a lever attached to the forward face of the control column
                and a differential relay controlled by the rudder bar.

          (b)   The live-line pressure (3,000 ± 150 lb./sq.in.) is shown
                on a triple pressure gauge (21) together with the pressure
                at each main wheel(1,500-1,650 lb./sq.in.).

          (c)   Should the hydraulic system fail, the pressure in the wheel
                brakes accumulator, which if fully charged should
                provide sufficient pressure for about 40 operations of the

33