AUTO GYRO CAVALON, Pilot Operating Handbook

Page: 91 / 147

Flight Manual
Cavalon
SECTION 7
SYSTEM DESCRIPTION
RSUK0287_POH_Cavalon Revision 3., Issue Date 06.04.16 7-3
7.5 Pneumatic System
Aircraft trim, rotor brake and activation of the pre-rotator is controlled by a pneumatic
system, consisting of an electrically driven air compressor with dry cartridge, a pressure
gauge in the cockpit, solenoid valves, air lines, pneumatic actuators, and the respective
cockpit controls.
Trim function
Trimming is effected by varying trim pressure in the pneumatic trim actuator which is
installed in parallel with the rotor head tilt for pitch control. Aft or nose-up trimming activates
the electrical compressor and increases trim pressure, causing the actuator to retract, and
tilting the rotor disc aft. Forward trimming opens the pressure relief valve to reduce trim
pressure and allows the rotor disc to flatten, due to the spindle head offset and the
gyroplane’s weight. The actual trim condition is indicated on the trim/brake pressure gauge
in the centre panel of the cockpit.
Lateral/roll trim works similarly, using a lateral pneumatic trim cylinder. Lateral trim condition
is indicated by a LED bar on the instrument panel.
Rotor brake
With the pneumatic mode selector in BRAKE position the operation of the pneumatic trim
actuator is reversed so that increased pressure causes the actuator to push the rotor head
up (or level) and presses a brake pad against the rotor head disc. In order to increase brake
pressure, move the 4-way trim switch on the stick grip aft. Note that this action will also
push the control stick forward. At full brake pressure the control stick will be maintained in
its full forward position.
Activation of the pre-rotator
The pre-rotator is activated when the button on the control stick grip is depressed provided
the following pre-conditions are met:
 pneumatic mode selector set to FLIGHT
 control stick in full forward position
 rotor brake pressure less than 3 bar
When activated the pneumatic clutch is engaged and engine torque is transmitted through a
90° gearbox and drive to the pinion which is engaged by another small pneumatic actuator
into the geared ring of the rotor head. The drive pinion is sliding on a helical gear to provide
automatic lock-out in case of rotor RPM overrun. The pre rotator drives shafts feature sliding
splined elements to accommodate drive shafts length changes due to rotor head and
engine operational movement.
Activation of the pre-rotator in BRAKE position
The pre-rotator can be activated in BRAKE position to park the rotor blades fore-aft for taxi.
To do so, the pre-rotator switch and the overdrive/override switch in the cockpit panel have
to be pressed simultaneously. Avoid prolonged activation of the pre-rotator with rotor brake
engaged.