gear rests against, and are held up by the in-
board gear doors.
Squat Switch System
General
Some airplane systems operate only on the
ground while others operate only in the air. The
squat switch system is designed to provide
the necessary ground or airborne signals to
these systems.
The squat switch system consists of four squat
switches (Figure 14-6), two on each main
landing gear torque link, and a squat switch
relay panel (SSRP). When the airplane is on
the ground and the struts are compressed, the
squat switches close to provide a ground mode
signal.
When the airplane lifts off, and the main land-
ing gear struts extend, the squat switches open,
interrupting the ground mode signals, thereby
shifting to the airborne mode.
Squat Switches
The squat switches provide ground or air sig-
nals directly to the following:
• Thrust reversers
• Spoiler system
• Landing gear control
• Brake control unit
• Squat switch relay panel (SSRP)
Squat Switch Relay Panel (SSRP)
The squat switch relay panel (SSRP) is lo-
cated on the aft pressure bulkhead. The SSRP
provides air/ground signals for numerous
equipment items. The following is a partial list-
ing of those items:
• Digital electronic engine computers (idle
schedule)
• Stall warning system
• Crew warning panel (master CAUT take-
off/landing inhibit)
• Nose wheel steering (enables operation)
• Cabin pressurization system
• Flap control system (test enable)
• Weather radar (test enable) and Forced
Standby (FSBY).
Main Gear Wheel and Tires
The main gears are fitted with dual aluminum
wheels and the tires are 22 x 5.75-12 inch, 12
ply rated tubeless (190 mph/165 knots rated),
serviced to 165±5 psi loaded, or 154±5 psi on
jacks. Each main gear wheel incorporates two
fusible plugs that prevent tire blowout caused
by excessive heat buildup (> 390°F) resulting
from hard braking or a brake malfunction.
14-8
FOR TRAINING PURPOSES ONLY
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
FlightSafety
international
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
FlightSafety
international
Figure 14-6. Squat Switch