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COCKPIT SHOULDER
WARMER
COCKPIT
FOOTWARMER
VENTS
CABIN FOOT
WARMER VENTS
EXHAUST
HEAT OVERBOARD
EXCHANGER
TEMPERATURE
CONTROL VALVE
THERMAL
ACTUATOR
HOT BLEED AIR
FROM ENGINE
CABIN SHOULDER
WARMERS
PRESSUREREGULATING
SHUTOFF VALVE
FLOW CONTROL
VALVE
CABIN
TEMPERATURE
COCKPIT SENSOR
TEMPERATURE
SENSOR
DUCT OVERHEAT
SENSOR
DUCT TEMP
SENSOR
TAIL CONE
TEMP SENSOR
REGULATED AIR
LEGEND
RAM AIR
HOT BLEED AIR
EXHAUST OVERBOARD
TAIL CONE BLD LK
DUCT O’HEAT L–R
PRESS OFF
Figure 11-1. Cabin Bleed-Air Systems
11-4 510OM-00
CITATION MUSTANG OPERATING MANUAL
Bleed-Air Distribution
Separate ducts route warm bleed air into the
cockpit (from the left engine) and into the
cabin (from the right engine).
The cockpit (left engine) bleed-air system
routes warm bleed air to the foot warmer outlets
above the pilot and copilot rudder pedals.
It also provides warm bleed air to defog the
side windows.
The cabin (right engine) bleed-air system
routes warm bleed air to the cabin shoulder
and foot warmer outlets.
Air from both bleed-air systems moves aft
through the cabin and exits through the outflow
valves (refer to Chapter 12—“Pressurization”).
A check valve permits flow from the right engine
(cabin) bleed-air system into the cockpit
bleed-air system if the left engine fails. This
keeps air flowing through the entire length of
the aircraft interior.
COMPONENTS
Heat Exchangers and Ram-Air
Ducts
Engine bleed air is cooled by a heat exchanger
in each engine pylon. Engine bleed air enters
and exits the precooler through bleed-air ducts.
Outside (ambient) ram air enters through the
pylon ram-air inlet on the leading edge of the
pylon and flows into the ram-air duct. It then
passes through the heat exchanger and flows
over the bleed-air ducts (the bleed air and ambient
ram air do not mix). Heat passes from the
bleed air to the ram air through the metal walls
of the separate ducts, cooling the bleed-air
inside the bleed air ducts.
The heated ram air exits overboard through a
temperature control valve in the ram-air duct,
carrying away most of the heat from the engine
bleed air. The ram air exits through the aft
pylon, into the engine exhaust stream. Forward
of the pylon ram air exhaust port, an eductor
projects into the engine exhaust stream, creating
a vacuum behind it to pull the ram air from
the pylon exhaust port.
During preflight, check that the pylon ram
air duct inlet and exhaust ports are clear
(Figures 11-2 and 11-3).
Temperature Control Valves
Aft of the heat exchanger in each ram air duct,
a thermally actuated temperature control valve
limits the ambient ram-air flow through the
Figure 11-2. Pylon Ram-Air Duct Inlet
Figure 11-3. Exhaust Ports
510OM-00 11-5
CITATION MUSTANG OPERATING MANUAL
duct to limit how much cooling ram air flows
through the heat exchanger. This determines
how much the heat exchanger cools the engine
bleed air and directly controls the temperature
of the bleed air before it enters the cabin.
Thermal Actuator
A thermal actuator adjusts the position of the
temperature control valve. The actuator responds
to the temperature of a gas inside the
actuator, which is heated by an electrical heating
element. The electrical heating element is
powered and controlled by an environmental
temperature controller.
If DC power is removed from the thermal actuator,
it cools and retracts, opening its temperature
control valve to maximum cooling. If the
actuator fails by leaking, a spring retracts it to
set the temperature control valve to maximum
cooling.
Cockpit and Cabin
Environmental PCBs
Each environmental PCB compares the temperature
in its respective zone (cockpit or cabin)
to the temperature setting selected by the crew
for that zone. It then compares this to the temperature
of the bleed-air supply in the ducts and
powers the thermal actuator that adjusts the
temperature control valve to allow more or less
cooling air through the heat exchanger. The resulting
heat exchanger temperature provides
cooler or warmer bleed air to that zone.
Each environmental PCB (cockpit/left and
cabin/right) is powered from the respective
electrical feed bus. If DC power for either
cockpit or cabin environmental PCB fails, the
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Cessna塞斯纳公务机飞行手册(59)
