P/N 11934-003
7-77
Cirrus Design
Section 7
SR20
Airplane Description
Overhead Dome Light
General cabin lighting is provided by a dome light located in the
headliner at the approximate center of the cabin. The dome light is
controlled through the OVERHEAD light control on the instrument
panel bolster. Rotating the knob clockwise from the off position will
illuminate the light and control its intensity. The lights are powered by
28 VDC supplied through the 3-amp CABIN LIGHTS circuit breaker on
Main Bus 2.
Environmental System
Cabin heating and ventilation is accomplished by supplying
conditioned air for heating and windshield defrost and fresh air for
ventilation. The conditioned air system consists of a heater muff (heat
exchanger) around the right engine exhaust muffler, an air mixing
plenum, air ducting for distribution, a windshield diffuser, forward
outlet valves, and cable controls for selecting temperature and flow.
Ventilation air is provided by ducting fresh air from air inlets, located in
each wing leading edge, to eyeball outlets for each occupant. Each
occupant can direct the fresh air flow by positioning the nozzle or
control flow rate from ‘off’ to maximum by rotating the nozzle.
Heating is accomplished by mixing ventilation air from the fresh air
inlets with heated air from the heat exchanger and then distributing the
‘conditioned’ air to the occupants and/or the windshield diffuser. Air for
heating is supplied by an inlet in the engine compartment to a muff-
type heat exchanger surrounding the right engine exhaust muffler.
This heated air is allowed to mix with fresh air from the wing root air
inlets in the air mixing plenum behind the instrument panel. The
proportion of heated to fresh air is pilot controllable. The mixed
(conditioned) air is then directed to the passenger outlets and/or to the
windshield diffuser. Conditioned air outlets for the forward occupants
are directionally controllable and are located beneath the instrument
panel at each position at knee level. Outlets for the rear occupants are
at floor level.
The temperature, volume, and flow selection are regulated by
manipulation of the cabin temperature and cabin air selector knobs on
the lower right side of the instrument panel.
Revision A5
Summary of Contents for SR20
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