21-40-01
99M90
Page: 8-6
Issued: May 9, 2012
Rev. New
I-Series Combustion Heater
Owners Manual
8.5
Spark Plug
Maintenance:
WARNING:
FAILURE TO TEST THE SPARK PLUG AND/OR THE IGNITION ASSEMBLY
BY METHODS LISTED HEREIN, WILL RESULT IN DAMAGE TO THE LEAD
ASSEMBLY, COIL ASSEMBLY, SPARK PLUG, OR VIBRATOR.
IT CAN
SHORTEN THE USEFUL LIFE OF THESE ITEMS AND MORE IMPORTANT-
LY, IT CAN CAUSE SERIOUS INJURY OR DEATH DUE TO ELECTRICAL
SHOCK AND/OR BURNS.
Three types of spark plugs are used on HET combustion heaters. The I-Series Aircraft Combustion
Heaters uses a Type III in all models except the I-1500 which uses a Type I. The Type I and Type III
are described and pictured in Chapter 6, Figures 6.1 and 6.3, of this manual. All of the testing
procedures for the spark plug are Chapter 6 as well.
WARNING:
DO NOT ARC IGNITION LEAD TO ANY GROUND EXCEPT THROUGH
APPROVED SPARK PLUG GROUND ELECTRODES. GROUNDING LEAD
TO JACKET IS DANGEROUS AND MAY CAUSE INJURY AND DAMAGE TO
THE HEATER IGNITION UNIT.
FAILURE TO TEST THE SPARK PLUG AND/OR THE IGNITION ASSEMBLY
BY THE PRESCRIBED TYPE III SPARK PLUG METHOD WILL RESULT IN
DAMAGE TO THE LEAD ASSEMBLY, COIL ASSEMBLY, SPARK PLUG, OR
VIBRATOR. AND MAY SHORTEN THE USEFUL LIFE OF THESE ITEMS.
DO NOT TOUCH THE SPARK PLUG WHILE ENERGIZED. IT HAS
DANGEROUSLY HIGH VOLTAGE AND MAY CAUSE INJURY OR EVEN
DEATH. MAKE SURE TO PLUG THE SPARK PLUG HOLE IN THE HEATER
TO PREVENT ANY POSSIBILITY OF RESIDUAL FUEL BLOWING OUT AND
IGNITING.
CAUTION:
NEVER INSTALL A TYPE II SPARK PLUG INTO AN I-SERIES HEATER.
SEVERE DAMAGE TO THE HEATER AND HEATER IGNITION UNIT WILL
OCCUR AND PHYSICAL INJURY MAY RESULT.
A. Removal: (Type I & Type III Spark Plug)
1.
Remove the necessary access panels to expose the spark plug area of the heater.
2.
Unscrew and remove the high voltage lead connector at the spark plug. Exercise care to
avoid fouling or damaging the connector.
3.
Remove the grommet.
4.
Using a 7/8 inch deep hex socket, unscrew and remove the spark plug. Make sure the
spark plug gasket is removed with the spark plug. It will normally stick on the spark plug
threads; but if loose, it might drop into the ventilating air passages of the heater. Should
this happen, remove the gasket with a wire hook.
B. Inspection and Servicing (Type I Spark Plug)
1.
If the spark plug appears to be in good condition, except for a mild coating of oxide on
the porcelain and electrodes, it may be cleaned and reused. Refer to Chapter 4, cleaning
information. If the electrodes are not eroded or damaged, re-gap the spark plug by carefully
bending the ground electrode until a 0.055 inch feeler gage can be inserted between between
the end of the center electrode and the ground electrode. (See Chapter 6.)
