Page 5-12
Pilot’s Operating Manual
Revision A1: Nov, 2002
Sub-section 5
HYDRAULICS
Hawker 800XP Pro Line 21
Section III - SYSTEMS DESCRIPTION
CONTROLS and INDICATIONS
FLUID STORAGE
The fluid supply for the auxiliary system is contained in a 6.01 U.S. pints (2.84 liter) reservoir located
adjacent to the nose gear bay.
A float switch in the reservoir is connected to an AUX HYD LO LEVEL annunciator. The annunciator
will illuminate when approximately 0.6 U.S. pint (0.28 liter) of fluid has been drawn out of the reservoir.
A full reservoir provides sufficient fluid for at least one emergency lowering of the landing gear, and
followed by at least one extension of the flaps to the landing position.
OPERATION
Selection of the auxiliary system is by pulling the red-handled AUX HYD SYSTEM PULL selector
handle.
Prior to selection, the system valves are set for normal main hydraulic system operation, i.e:
• On/off valve - open to relieve fluid seepage from the Auxiliary system.
• Dump valve - set to connect Main system pressure and system return to the main and nose gear
lines.
• Shuttle valves - With no pressure in the auxiliary system, the shuttle valves close the auxiliary
system supply ports on the landing gear jacks, allowing main system pressure to operate the
jacks.
With the lever in the normal position, a baulk prevents operation of the auxiliary system hand pump.
The system is prepared for use by first inserting the rudder gust lock handle into the AUX HYD SYSTEM
hand pump socket and then firmly pulling the red-handled PULL handle. This action operates the
system valves as follows:
• On/off valve - closed to prevent the auxiliary system fluid passing to the return line.
• Dump valve - set to cut-off the main system pressure and remove any main system pressure in
the landing gear path by interconnecting the normal up and down lines of the main and nose gear
jacks to the return line.
Pulling the control lever also releases the baulk and permits operation of the hand pump. The control
lever is held in the selected position by a spring unit.
CONTROL
LOCATION
AUX HYD SYSTEM PULL selector handle
Left side of center instrument panel,
adjacent to FMS No. 1 display
EMERG HYD PUMP operating handle socket
Pilot’s floorboard, adjacent to the center pedestal
AUX HYD LO LEVEL annunciator
MWS main panel
Auxiliary reservoir contents level indicator tube
Visible from nose gear bay
