CSP
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902RFM207E
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1
ROTORCRAFT FLIGHT MANUAL
MD900 (902 Configuration with PW 207E)
Systems Description
Original
7
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39
Reissue 2
7
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14. ENVIRONMENTAL CONTROL
The environmental control system for the helicopter consists of the ventilation sys
tem and the heat/defog system.
Ventilation System:
Ambient air is taken in through an inlet in the right side of the upper cowling,
is directed through a water separator and a two-speed fan, and into a manifold
that distributes the air to the cockpit and to the cabin - then out of a port in
the baggage compartment door. In the cockpit, four adjustable gaspers, two on
the windshield's center bow blow outboard toward the pilots' heads, and two
on the forward door frame blow inboard toward their lower torsos. Six adjustable
gaspers are mounted in the ceiling of the cabin. The fan speed switch is located
on the Utility Panel.
Secondary ventilation for the cockpit is provided by two conventional clear plastic
adjustable snap vents in the window of each cockpit door.
Heat/Defog System:
The heat source is bleed air from the compressors of the two engines. This hot
air is directed through a pilot-operated on/off valve located on the Utility panel
to a pair of ejectors that mix bleed air and ambient air to a desired temperature
and flow rate. One ejector serves the cockpit; the other serves the cabin.
The cabin ejector is located low on the right side of the cabin just aft of the
door. Its discharge air is directed across the cabin under the rear seats. An adjust
ing lever for controlling the bleed air admitted to the ejector, and so the discharge
volume, is recessed in the wall at head height directly above the ejector.
The cockpit ejector is located in the compartment below the pilot's seat, and
is operated by a push/pull control mounted vertically along the right hand side
of the console. From the ejector, warm air is ducted forward to two aft-facing
nozzles above and forward of the pilots' feet, and to a pair of nozzles along the
bottom of the upper windshield panels to defog them. Each pilot has a push/pull
knob located under the instrument panel to operate a butterfly valve that modu
lates the airflow toward his/her feet.
An automatic disconnect monitored by the IIDS cuts off all bleed air whenever
either engine becomes inoperative in flight to maximize the operating engine's
power output to the rotor. This cutoff function maybe overridden by placing the
CAB HEAT switch in the OVRD position.
Summary of Contents for MD900 Explorer
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