Heating And Ventilating System Operating Controls; Operating Procedure; Inspection Of Heater And Heater Components; Preflight And Or Daily Inspection - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
13-12. OPERATING CONTROLS.
NOTE
The schematic diagram (Figure 13-6) shows the heater circuit.
including the electrical wiring in the airplane.
a.
The HEATER SWITCH is connected in the line that supplies electrical power to all heater
equipment and controls. When this switch is in the OFF position. the entire heater system is inoperative.
This switch has a FAN position which permits use of the ventilating air blower to circulate cool air through
the system for summer ground operation. With the switch in FAN position. the heater is inoperative and
only the ventilating air blower is energized.
b.
The HEATER SWITCH is a normally open switch that supplies power to "lock-in" the safety
relax through which power is supplied to the ignition and fuel circuits of the heater.
13-13. OPERATING PROCEDURE.
(Refer to Figure 13-6.)
a.
Place the HEATER SWITCH in the ON (or HEAT) position. The ventilating air and combustion
air blowers should operate.
b.
For S N's 31-8052001 and up: Momentarily depress the Heater Start Reset switch. The Heater
Fail annunciator light should go out.
c. The heater will ignite and continue to operate.
d.
The DUCT SWITCH can be set to regulate the cabin temperature for desired comfort level If this
switch is set for ground operating comfort. it may be necessary to reposition it after being airborne. since
ram air will increase the ventilating air flow and the heater output. An override micro switch is incorporated
on the duct switch to override the duct stat at the very last movement of the duct stat arm toward the high
position.
e.
To stop heater operation. turn off the HEATER SWITCH.
It is desirable to operate the fan several minutes to cool the heater after operation To stop Fan
operation. turn OFF the HEATER SWITCH.
13-14. INSPECTION OF HEATER AND HEATER COMPONENTS.
d.
Inspect all fuel lines and fittings for fuel stains. indicating leakage. and replace lines or tighten
fittings as necessary
b.
Check heater for loose bolts. screws. and wiring.
c.
Inspect all electrical connections for corrosion. If corrosion is evident. clean affected components.
and wipe clean with a lightly oiled cloth.
13-15. PREFLIGHT AND OR DAILY INSPECTION.
a.
Inspect the ventilating air inlet scoop. combustion air inlet scoop. exhaust outlet and fuel drain
for possible obstructions. Make sure that all of these openings are clear of any restrictions and that no
damage has occurred to air scoop protrusions.
b.
Perform an operational check as follows:
I.
Place the HEATER SWITCH in theON (or HEAT) position. The ventilating air blower and
combustion air blower should operate. Operate both combustion air blower and ventilating air blower and
check each for unusual current draw. noise or vibrations.
NOTE
To proceed with the operational check. follow paragraph 13-13
entitled Operating Procedures. steps a through e. This procedure
should be repeated one or more times.
Revised: 10/15/82
HEATING AND VENTILATING SYSTEM
4B12