Selkirk College IATPL Program Manual
Beech 95 POH
Effective September 1, 2005
Appendix 14 - 75
Above diagram shows how heater works. Note that combustion air enters through a
separate inlet (not through the iris valve.)
Outside air is heated in a shroud that surrounds the combustion chamber and from there is
collected in a plenum. Flexible ducts are then used to direct heated air to three cabin
outlets, the defroster on the dash, the pilot, and co-pilot outlets below the instrument
panel. A separate pull-push knob labeled controls each of these three outlets. The pilot air
and defroster knobs are below the pilot sub-panel and the co-pilot air knob is below the
panel on the right side.
A cycling thermostat mounted in the co-pilot air outlet, behind the instrument panel,
controls cabin temperature. The Cabin Temperature control knob, below the pilot side
sub-panel, sets this thermostat. Pushing the knob in sets a lower temperature and pulling
it out sets a higher temperature. The maximum temperature that can be set is 82 C.
For normal operation the cabin air knob (T-handle) should be all the way in (iris valve
fully open.) However, in very cold outside air temperatures the cabin may remain cold
even with the Cabin Temperature knob pulled all the way out. It is possible to obtain
more cabin heat, in this situation, by pulling the cabin air knob part way out, partially
closing the iris valve.
For safety, a normally open fuse in the heater discharge plenum will close, making the
system inoperative, if the temperature in the plenum exceeds 150 C. This fuse is located
on the upper bulkhead behind the instrument panel where it cannot be reached in flight. If
this fuse activates in flight have an AME repair the heater before further attempts to use
it.
Fuel for the heater is drawn from the left main wing tank by two electric fuel pumps.
Only one pump operates during ground operations. The same switch that controls the
electric blower, for ground operations, accomplishes this.
The heater fuel line is equipped with a strainer that can be drained from the nose gear
compartment.
A spring-loaded electric solenoid closes when the heater is turned off, preventing fuel
from seeping into the heater.
The heater has an ignition unit that provides spark to initiate and sustain combustion. The
igniter unit requires a vibrator to provide interrupted current for the high voltage coil. The
vibrator unit has two sets of points that an AME can place into service; but there is no
provision for pilot selection of these points. If the heater fails to operate in flight it may
be due to the need to switch these points.
When not in use for heating the heater system can be used to deliver cool air to the cabin.
In flight, simply push the cabin air knob all the way in and open the pilot air, defroster,
Summary of Contents for Beech 95 2017
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