Beechcraft Duchess 76 - Heater Operation

BEECHCRAFT
Duchess 76
section VII
Systems Description
The manual reset limit (overheat) switch (inaccessible during
flight), located
on the heater, shuts off the heat system in
case the discharge temperature reaches 300
0
F.
CAUTION
The entire system should be inspected and the
ma!function determined and corrected before re-
setting the overheat switch.
HEATER OPERATION
1. The three-position switch on the pilot's subpanel,
placarded HEATER - ON, BLOWER ONLY, OFF, must
be in
the ON position to place the heating system in operation.
2. The push-pull knob on the left sidewall, placarded DE-
FROST - PULL ON, controls the amount of air required for
windshield defrosting.
3. The push-pull knob, located below the defrost knob,
placarded CABIN
AIR - PULL OFF, controls the amount of air
entering the cabin from the heater. Pulling the knob more
than approximately one-half
closed.. c;I~activates the heater in
order to prevent heater overtemp.
NOTE
For maximum heat, the CABIN AIR control can
be pulled partially out to reduce the volume
of
incoming cold air and permitting the heater to
raise the temperature of the admitted air. How-
ever, if the CABIN AIR control is pulled out more
than halfway, the heater will not operate.
January 1978
7-37