Synchrophaser Troubleshooting - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
NOTE
The above step must always proceed phase operation when flying
or making ground checks. Always use manual selection for
stand-by service.
f. Start and adjust the master LEFT engine at near cruise RPM (2200 RPM or above). Set the
selector switch to propeller sync. Rotate the slave RIGHT engine with the use of the starter (right magneto
switch OFF) until the zero center reading voltmeter deflects to the right or left of center. A full deflection
to the right indicates a photo conductor is supplying a signal to the computer amplifier and must cause the
ammeter to increase slowly to a maximum of approximately 1.75 amperes.
g. When the above condition is met, rotate the slave RIGHT engine with the use of the starter to a
position that will cause the zero center reading voltmeter to deflect to left of center. A full deflection to left
must cause a slow amperage decrease to 0 amps. This indicates that the other conductor is supplying a signal
to the computer amplifier.
NOTE
A decrease in solenoid current indicates the slave engine is in-
creasing RPM. An increase in solenoid current indicates the slave
engine is decreasing RPM.
When conditions of Step h and i are met, it will confirm that all
components are operating.
h. Return the selector switch to manual and start the slave RIGHT engine. Operate the master LEFT
engine at near cruise RPM. Set the selector switch to propeller sync position and advance the slave engine
speed slightly over that of the master engine noting the deflection of the voltmeter. If it remains to the right
decidedly longer than it remains on left, it confirms that the signals from the photo conductors are correct.
i. While still operating the master engine at near cruise RPM, retard revolutions of the slave engine
to less than that of master engine. Note the deflection of the voltmeter. If it remains to the left decidedly longer
than it remains on the right, it confirms that the signals from the photo conductors are correct.
NOTE
The voltmeter readings will change from side to side with RPM
and phase changes, but will show a definite tendency to stay to
right or left of zero when engine RPM's are not in phase.
14-138. TROUBLESHOOTING. The following checks should be made when a malfunction of the system
is suspected. The checks are divided into two parts, Mechanical and Electrical, and should be performed in
that order. A troubleshooting chart is also supplied at the end of these instructions.
CAUTION
Before proceeding any further be certain that the magneto switches
are OFF.
Reissued: 9/23/80
ACCESSORIES AND UTILITIES
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