21-40-01
99M90
Page: 4-2
Issued: May 9, 2012
Rev. New
I-Series Combustion Heater
Owners Manual
NOTE:
Prior to cleaning the heater whether mounted on the aircraft or as
removed, observe and note condition. Look for any signs of hot
air or exhaust leaks, electrical arcing from wiring or ignition, and
cracks or tears in the heater jacket or other heater parts.
4.3
Exterior Cleaning
CAUTION:
DISCONNECT ALL ELECTRICAL POWER OR OTHER SOURCE OF
IGNITION AS CLEANING AGENTS MAY BE FLAMMABLE. FAILURE TO
OBSERVE THIS CAUTION MAY LEAD TO AN UNCONTAINED FIRE
WHICH MAY RESULT IN DEATH, SERIOUS BODILY INJURY, AND/OR
SUBSTANTIAL PROPERTY DAMAGE.
If mounted on an aircraft/rotorcraft, initial cleaning may be done using mineral sprits or isopropyl
alcohol under pressure. Blow dry using clean shop air. Do not direct cleaning spray into the
heater inlet or exhaust. Some heater installations are remote, do not allow cleaning fluids to
accumulate and run into the airframe especially when using mineral spirits. Place shop towels
below the heater to absorb any residue while cleaning.
If removed, initial cleaning should be done using a shop cloth and mineral sprits or isopropyl
alcohol. Wipe dry using clean shop cloths.
4.4
General Component Cleaning
NOTE:
If components other than the air blowers or spark plug are
removed and need cleaning, refer to the HET Combustion Heater
Overhaul & Maintenance manual P/N 99M91 for more detailed
cleaning and repair information.
Components separated during disassembly, may be cleaned in several ways.
- Aluminum components: Use of degreaser or solvents should be used by spray or
wiping, however, dipping or immersion may be used if attended. Aluminum may
degrade if left in degreasers or solvents for extended periods of time. Consult the
directions for the agent being used.
- Metallic components: Most metallic components may be dipped or immersed for
cleaning including combustion tube. Use a dry cleaning solvent such as Stoddard
solvent (Federal Specification P S.661). Mechanical means such as bead blast may
be used however, it is not advised on most of the heater parts as they may become
misshapen. Sand blasting is not approved. Great care must be taken with the motor
armature or armature housing cleaning. Aggressive cleaning may fracture the
coating on wire or delicate connections. Use mineral spirits or isopropyl alcohol for
cleaning. Blow drying must be done using low pressure air to avoid damage to wire
insulation, air drying is preferred.
If hardware does not clean sufficiently with degreaser or solvents, replace the
hardware with new. (Hardware is a required replacement part for overhaul.)
- Non-metallic components: Plastic or fiber components such as insulators, must be
cleaned with isopropyl alcohol. Fiber components that have absorbed or “wicked” oil
cannot be cleaned effectively and should be replaced. Electrical terminals or strips
may be cleaned with electrical contact cleaner. Wipe or spray soak and air dry.
