Teledyne Continental Motors, Inc.
TM
Maintenance and Adjustments
IOF-550 Permold Series Engine Maintenance Manual
9-17
1 April 2007
9-4.
Ignition System Maintenance
9-4.1. Spark Plug Replacement
Procedure
1.
Remove the ignition harness leads from all spark plugs.
2.
Remove the spark plug from the top and bottom of each cylinder. Mark each plug’s
installed location during removal.
3.
Inspect the spark plug electrode condition using Figure 9-6 for spark plug
serviceability information. Discard any spark plugs which do not meet the “normal
electrode condition” characteristics.
NORMAL ELECTRODE CONDITION
•
INSULATOR TIP GRAY, TAN OR LIGHT BROWN
•
FEW COMBUSTION DEPOSITS
•
ELECTRODES NOT BURNED OR ERODED
•
PROPER TYPE AND HEAT RANGE PLUG FOR
ENGINE AND SERVICE.
•
SPARK PLUG SHOULD BE CLEANED, REGAPPED
AND TESTED BEFORE REINSTALLTION
NORMAL WORN-OUT CONDITION
SEVERE WORN-OUT CONDITION
•
ELECTRODES ERODED BY HIGH VOLTAGE
SPARKING AND BY CORROSIVE GASES
FORMED DURING COMBUSTION TO LESS THAN
1/2 ORIGINAL THICKNESS
•
MORE VOLTAGE NEEDED TO FIRE SPARK
PLUGS - OFTEN MORE THAN IGNITION
SYSTEM CAN PRODUCE.
•
REPLACE WITH NEW APPROVED AVIATION
SPARK PLUGS.
•
EXCESSIVELY ERODED CENTER AND GROUND
ELECTRODES PLUS EXTENSIVE NECKING OF
FINE WIRE GROUND ELECTRODES INDICATE
ABNORMAL ENGINE POWER OR PLUGS
LONG OVERDUE FOR REPLACEMENT.
•
DISCARD SPARK PLUGS AND CHECK HEAT
RANGE BEFORE INSTALLING NEW ONES.
•
REPLACE WITH NEW APPROVED AVIATION
SPARK PLUGS IN APPROPRIATE HEAT RANGE.
FINE WIRE ELECTRODE
MASSIVE ELECTRODE
Figure 9-6.
Spark Plug Inspection Criteria
4.
Remove and discard the copper gasket from all reusable spark plugs.
5.
If a new spark plug is required, select one of those listed in Table 9-4 or the most
current version of SIL 03-2 “Currently Active Approved Spark Plug Application” to
determine the type of spark plugs to be installed.
