Heli-Coil ® Replacement - Lycoming TEO-540-C1A Maintenance Manual

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20. Heli-Coil Replacement
A. Replace the spark plug Heli-Coil
spark plug hole in the cylinder are damaged (usually occurs when hard carbon on the end of
the spark plug causes the insert to unwind during spark plug removal).
NOTICE: Always install a larger oversized 0.010 in. (0.254 mm) Heli-Coil
plug hole on the cylinder head to replace a standard sized Heli-Coil
replace a standard sized Heli-Coil
insert. The oversize Heli-Coil
the Heli-Coil
(1) Disable all power to the engine to prevent propeller rotation and engine start. Disconnect
ignition leads from all spark plugs.
(2) If not already done, remove the Heli-Coil
(a) Insert the T-shaped Removing Tool
P/N 64595 (Figure 51) in the spark
plug hole. Press the tool down
firmly for the edge of the tool to cut
into the top thread of the insert.
(b) Turn the tool counterclockwise to
the remove the insert.
72-30
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insert (Figure 49) in the cylinder head if the threads in the
Figure 49
Heli-Coils
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insert as shown Figure 50.
Figure 50
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Heli-Coil Inserts for Long Reach Spark Plugs
TEO-540-C1A Engine Maintenance Manual
TEO-540-C1A Engine Maintenance Manual
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insert with another standard sized Heli-Coil
inserts are identified by three marks on the tang of
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insert from the spark plug hole as follows:
Removing Tool P/N 64595
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insert in the spark
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insert. Never
Figure 51
November 2018
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