addition to providing a duct temp reference for
the automatic temperature control mode of
operation, they provide output signals for
CKPT and CAB duct temp indications on the
ECS Systems page on the EICAS/MFD. They
also provide output signals that will activate
the “CKPT DUCT OVHT” or “CAB DUCT
OVHT” CAS message if the temperature in the
cockpit duct or the left side cabin duct reaches
300° F. The right side cabin temp sensor has
only one function, which is to activate the
“CAB DUCT OVHT” CAS message if tem-
perature in the right side cabin duct reaches
300° F.
The cockpit and cabin duct temperature lim-
iters are used to shutoff bleed air through the
corresponding CKPT or CAB TEMP CONT
VALVE if the temperature in cockpit duct or
the right side cabin duct exceeds 210° F (Auto
mode).
Temperature Control Valves
The temperature control valves (Figure 11-4)
are operated by servo pressure regulated by
torque motors. If no pressure is being sup-
plied from the respective torque motor, the
valve is held closed by spring pressure.
The Integrated ECS Temperature Controller
regulates the torque motors which allow servo
air to override the spring pressure and open
the temperature control valves.
A loss of electrical power to a torque motor
shuts off servo air to the valve and spring pres-
sure closes the valve (full cold position).
CONTROLS AND OPERATION
The cockpit and cabin temperature controls are
located on the environmental control panel on
the copilot’s instrument panel (Figure 11-6).
In the automatic mode, the MANUAL TEMP
s w i t c h / i n d i c a t o r ( S / I ) w i l l b e b l a n k .
Temperatures are controlled using the selec-
tor knobs that have a value range from ap-
proximately 60° F (15° C) when the knob is
turned to the COLD position, to approxi-
mately 90° F (32° C) when the knob is turned
to the HOT position. Duct air temperature is
automatically controlled within the range of
37° to 180° F.
Temperature sensors within the cockpit and the
cabin transmit temperature information to the
Integrated ECS Temp Controller (Figure 11-
4). The Integrated ECS Temp Controller then
signals the torque motors to modulate the tem-
perature control valves, allowing a greater or
lesser amount of hot bleed-air to mix with the
conditioned air.
In the manual mode, an ON caption is illu-
minated within the MANUAL TEMP S/I,
when selected. In manual, the pneumatically
positioned temperature control valves operate
11-8
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
Table 11-1. AIR CONDITIONING SYSTEM CAS MESSAGE DATABASE