Oil and water accumulation. Open
the siphon valve and drain accumulated water and oil
Maintenance. Consult the applicable
maintenance manual for scheduled and preventive
Aircraft Preheater. The aircraft preheater,
shown in figure 9-15, will deliver 40,000 to 400,000
BTUs/hour within the specified operating condition
limits. The preheater will deliver uncontaminated air
with a regulated discharge air temperature of 150 to
280°F (66 to 138C)at an adjustable air delivery rate of
435 to 815 cfm. Flexible ducts are used to direct the
heated air where it is needed.
Purpose. The aircraft preheater is
specifically designed to preheat aircraft engines,
cockpits and cabins when the aircraft is in cold weather
areas. It is often used to provide heat to aircraft
repairers as they perform outdoor maintenance in the
Principles of operation. The aircraft
preheater has a prime mover assembly and a heat
Prime mover assembly. The prime
mover is either a gas engine or an electric motor which
drives afan, a fuel pump, and a magneto. The fan
moves the air to be heated through the heat exchanger
section of the heat generator and also supplies the air
for combustion. The fuel pump supplies fuel for
combustion in the heat generator and to run the gas
engine. The magneto ignites the combustion fuel and
air mixture in the combustion portion of the heat
Heat generator assembly. Through
the medium of a heat exchanger, the heat generator
heats the inlet air with hot gases generated by fuel
burned in the combustor. The air and exhaust flow are
so arranged that there can be no intermingling of
exhaust gases with the heated air.
Safety practices and procedures. The
following special precautions should be observed when
using the aircraft preheater:
· Do not use inside a structure due to possible
carbon monoxide poisoning. Park the preheater
outside and run ducting to the inside.
· Periodically look for leaks in the fuel system.
· Locate the unit so that the exhaust does not
blow into the inlet door.
· Let the unit cool down before refueling.
· Be sure the exhaust stack extension is in place.
· Ensure all outlet and inlet access doors are
applicable maintenance manual for detailed instructions.
The following general procedures pertain to the
operation of the aircraft preheater:
Position the preheater so that the
wind blows the exhaust away from the air inlet opening.
Open the air inlet canopy door, air
outlet doors, access doors, and the exhaust stack door.
Connect the flexible duct and
position it as needed.
If using the gas engine prime
mover, start the engine. If using the electric motor
prime mover, plug it in to a power source, normally 115
vac, and turn switch on.
Regulate the heat by using the
temperature selector valve.
To stop the preheater, pull the
burner fuel knob to stop the combustor fire. Allow the
prime mover to run for about 2 minutes for cooling
Stop the prime mover by pressing
the stop switch button on the gas engine or by turning
the switch on the electric motor to off.
Inspection. The operator should perform
the following general inspections before using the
aircraft preheater. Detailed inspection requirements are
found in the applicable maintenance manual.
Gas tank. Check the level and refill