Technical data

13773-001
21-00
Page 1
ENVIRONMENTAL SYSTEMS
1. GENERAL
The airplane fresh air and conditioned air systems are covered in this chapter. 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.
Cabin heating and ventilation is accomplished by supplying conditioned air for heating and windshield
defrost and fresh air for ventilation. The system consists of a heater muff (heat exchanger) around the
engine exhaust muffler, fresh air inlets in each wing, an air mixing plenum, air ducting for distribution, a
windshield diffuser, heating outlets, fresh air outlets, and cable control 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 eyeball outlets to
a new location. Each occupant can control flow rate of the eyeball outlet by rotating the outlet.
Heating and windshield defrost 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 through an inlet in the engine baffling to a muff-type heat
exchanger surrounding the engine exhaust muffler. This heated air is allowed to mix with fresh air from the
leading edge air inlets in the air mixing plenum behind the instrument panel. The proportion of heated air 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 knee level at each position at knee level. Outlets for the rear
occupants are at floor level. (See Figure 21-001)
2. TROUBLESHOOTING
Trouble Probable Cause Remedy
Controls/Inoperable Control linkage jam nuts loose/dis-
connected
Adjust and secure control linkage
(Refer to 21-60)
Defroster System Inoperable Control jam nuts loose/discon-
nected
Defroster vent holes blocked
Heater muffler hose disconnected
or collapsed
Adjust and secure control linkage
(Refer to 21-60)
Remove restriction
Connect hose
Fresh Air System Inoperable Eyeball vents closed
Inlet vents covered, plugged, or
restricted
Fresh air inlet hose disconnected
or collapsed
Open vents
Remove obstruction
Connect inlet hose, repair hose
Cabin Occupants Become Disori-
ented, Tired, or Nauseated. Com-
plaints of headaches
Exhaust gasses leaking into the
heater muffler
Pressure test heater muffler and
replace if leaking
Poor Temperature Control Duct work is disconnected or has
a hole in it or is collapsed
Connect or replace duct work
(Refer to 21-60)
30 Nov 2000