Piper Navajo PA-31 Service Manual page 508

PIPER NAVAJO SERVICE MANUAL
NOTE
When withdrawing the ignition cable lead connection
from the plug, care must be taken to pull the lead
straight out and in line with the center line of the plug
barrel;
otherwise a side load will be applied, which
frequently results
in damage to the barrel insulator
and connector.
If the lead cannot be removed easily
in this manner, the resisting contactbetween the neo-
prene collar and the barrel insulator will be broken
by a rotary twisting of the collar.
Avoid undue dis-
tortion of the collar and possible side loading of the
barrel insulator.
b. Remove the spark plug from the engine. In the course of engine operation,
carbon and other combustion products will be deposited on the end of the spark
plug and will penetrate the lower threads to some degree.
As a result, greater
torque is frequently required for removing a plug than for its installation.
Ac-
cordingly, the torque limitations given do not apply to plug removal and sufficient
torque must be used to unscrew the plug. The higher torque inremoval is not as
detrimental
as in installation,
since it cannot stretch the threaded section.
It
does, however, impose a shearing load on this section and may, if sufficiently
severe, produce a failure in this location.
NOTE
Torque indicating handle should not be used for spark
plug removal because of the greater torque require-
ment.
Reissued: 10/12/79
POWER PLANT
2J10