Cabin Temperature; Engine Synchrophaser; Synchrophaser System Operating Procedure - Piper Navajo Chieftain PA-31-350 Service Manual

NAVAJO CHIEFTAIN SERVICE MANUAL
2.
In the e aporator area the fittings at and around the expansion valve. Refer to paragraph 14-91.
3.
Although the above areas seem to be most susceptible to leaks. all fittings are subject to leaks and
should be checked.
4.
Because of the planned leaks at the compressor shaft seal and the freon loss of the rubber hoses.
Piper Aircraft Corporation has discontinued the use of Freon 12 with Dytel. The red dye also shows up the planned
leaks as well as other leaks.
14-133. CABIN TEMPERATURE.
Air temperatures should be measured at the six individual outlets and recorded to check the efficiency of the
system. A temperature differential should range from 24°F to 29°F between the outlet temperature and outside
temperature.
If the temperatures don't fall within these figures the system should be checked for leaks. Refer to Table
XIV-XIV for possible causes.
14-134. ENGINE SYNCHROPHASER.
PA-31-350, S/N 31-5001 and up.
14-135. DESCRIPTION
OF SYNCHROPHASER
SYSTEM. (Refer to Figure 14-43.)
This system consists of a pulse generator. a strobe sensor (replaced b\ another pulse generator in S/N
31-7852038 and up). a computer. and an electrical control solenoid on the governor.
The pulse generator located on the master LEFT engine supplies timing information to the strobe sensor on the
slave RIGHT engine. The resultant error signal. generated by the strobe sensor is fed to the computer that in turn
dries the servo amplifiers. The output of the servo amplifiers controls the electrical solenoid on the slave engine
governor. This control action keeps the slave engine in phase with the rotation of the master engine
NOTE
S/N 31-7852038 and up have a second generator in lieu of the strobe
sensor. The signals from both generators are supplied directly to the
computer for comparison. The difference signal is amplified and fed to
the goernor solenoid to control the slave engine.
The pulse generator is mechanically driven by the camshaft of the master LEFT engine. One rotation
of the camshaft constitutes one cycle of engine operation of a four stroke engine. This permits the pulse
generator to be timed to any relationship to the firing order of the engine. The strobe sensor is likewise
driven by the camshaft on the slave engine. This gives a latitude of selection, permitting any selection of
corresponding operation between master and slave engine.
The selector switch on the panel has two positions, manual or phase. In the manual position, engines
and propellers are operated and controlled in the conventional manner. After manually synchronizing
engines, the selector switch can be set to the phase position. This permits the synchrophaser to hold engines
in RPM agreement and also in the preselected phase relationship.
14-136. SYSTEM OPERATING PROCEDURE. PA-31-350. S/N 31-5001 and up.
The selector switch should be in the manual position during engine start, taxi and warmup. The switch
may be turned to phase position after the take-off run has started, if desired.
NOTE
With full throttle and full RPM the governors should be set within
the synchrophasing range, if not consult Section VIII of this
Service Manual for high RPM setting adjustment.
Reissued: 9/23/80
ACCESSORIES AND UTILITIES
415