Acu Valves; Distribution - BOMBARDIER Challenger 601-3A CL-600-2B16 Pilot Training Manual

L-14TH STAGE-R
PUSH
BLEED BLEED
ON/
CLOSED CLOSED
DUCT OFF DUCT
FAIL FAIL
DUCT MON
LOOP A
BOTH
LOOP B
10TH STAGE
BLEED BLEED
CLOSED CLOSED
OPEN
DUCT DUCT
FAIL
L ISOL
Figure 11-2. Bleed-Air Panel

ACU VALVES

Each ACU has a dual-pressure regulating and
shutoff valve controlled through separate ACU
switch-lights labeled "L" and "R" on the bleed-
air control panel (Figure 11-2). Each ACU valve
requires electrical power and pneumatic pressure
for operation. The electrical power is supplied
from DC bus 1 and DC bus 2, respectively.
Each ACU valve operates automatically in ei-
ther high or low modes. For example, the ACU
valves operate in a high mode on the ground
if the pneumatic source is the APU. This is to
ensure sufficient cooling air across the heat ex-
changers to compensate for the absence of
ram-air cooling. This ground airflow is in-
duced by ejectors in the ram-air ducts. The
ACU valves will also operate in a high mode
in flight if one ACU is selected off.
Each ACU switchlight has a split legend which
illuminates as a white "OFF" or as an amber
"FAIL." When both appropriate DC power
and pneumatic pressure are available, pushing
an ACU switchlight will cause the OFF light
to extinguish and the valve to open. During op-
eration, with the ACU valve open, if pressure
in an ACU exceeds the design limit, the ACU
valve will try to automatically close and the
amber FAIL legend in the switchlight will il-
luminate. Because this overpressure condi-
tion could be caused by a faulty valve, the
associated left or right engine bleed-air valve
and the isolation valve (if open) will close at
the same time. The BLEED CLOSED light
will illuminate for the affected engine BLEED
11-4 CL 601-3R
10TH STG
BLEED
AIR
100 100
B
50 50
L
E
0 0
PSI
E
L R
D
PUSH
ON/
OFF
OFF OFF
FAIL FAIL
FAIL
R L ACU R
FOR TRAINING PURPOSES ONLY
FlightSafety Canada
CL-600-2B16 PILOT TRAINING MANUAL
AIR switchlight and the OPEN light for the
ISOL switchlight will extinguish.
If a problem is caused by overtemperature in
the ACU, the affected ACU regulating and
A
shutoff valve will close and only the ACU
I
R
amber FAIL light will illuminate. The engine
bleed-air valve and isolation valve (if open)
will remain open.
To prevent damage to the ACU, if the pressure-
regulating and shutoff valve fails to close
when the ACU is deselected, an ACU FAIL
light will illuminate.
In either case, the serviceable ACU will au-
tomatically go to high mode.

DISTRIBUTION

Air distribution to the occupied areas is
achieved by a ducting system (Figure 11-3) on
the right and left sides of the cabin and cock-
pit. Cold air ducts using adjustable gasper-
type outlets are located above each passenger
seat, on the cockpit overhead panel. The cold
air duct is extended behind the instrument
panels to provide for instrument cooling. Cabin
air exhaust is vented to the underfloor area,
while cockpit air is exhausted to under the
cockpit area for avionics cooling. All exhaust
air from the occupied areas flows aft to the
pressurization outflow valves in the rear pres-
sure bulkhead.
L t é e
L t d .