tionship between exhaust gas temperature and
engine speed during tabbing. (Tabbing
is the procedure to adjust fixed or variable
exhaust gas tail cone areas during normal
aircraft checks every 30 to 50 hours.)
To check aircraft fire detector, overheat
detector, and wing anti-icing systems
by using tempcal probes.
Refer to the MIM of a particular aircraft for
the proper procedure when you check and adjust
the variable nozzle systems. You can get detailed
instructions for adjusting the EGT with the
JETCAL analyzer from the applicable MIM.
REVIEW SUBSET NUMBER 9
Q1. Which piece of test equipment would you
use to test an engine ignition unit output
in sparks per second?
Figure 2-35.-Synchrophaser test set.
Q2. Before using the TTU-27/E test set, what
connection must you make to ensure proper
The output of synchrophaser-associated com-
operation?
ponents is simulated by the test set. It provides
a simulated tachometer signal and the resistance
of synchrophaser controls for certain tests. When
Q3. What is the minimum voltage for using the
programmed, these signals help measure the
TAKCAL unit of the JETCAL Analyzer?
synchrophaser dynamic response to off-speed,
off-phase, speed reset, resync, and throttle
anticipation signals.
Control adjustments are minimal. Only a few
SYNCHROPHASER TEST SET
of the automatically programmed tests require
adjustment of either of the feedback gain
potentiometers. The accuracy of control adjust-
The synchrophaser test set (fig. 2-35) tests
propeller synchrophaser electronic units. The test
ment is optimized by designing test set circuits that
require few adjustments. This adjustments will be
set generates all pulses (dc and ac) required to test
the synchrophaser electronic unit independent of
to null or zero settings on center-scale zero meters.
A high degree of accuracy and repeatability
its associated components.
is a feature of the gain measuring circuits within
The test set is completely solid state. Each
switch position programs a particular test. It does
the tester. Conventional gain circuits require
this by connecting the appropriate inputs to the
application and measurement of incremental
voltages to the synchrophaser for comparison with
synchrophaser and the meter required to verify
resultant output voltages. The gain measurement
synchrophaser performance.
The test set generates a master pulse and a
circuit has a galvanometers, demodulator, dc
slave pulse. The pulse circuits closely simulate the
power supply, and calibrated potentiometer in a
synchrophaser pulse input under dynamic flight
bridge circuit. When the gain test is programmed,
rotate the calibrated potentiometer to null the
conditions. You program different phase and
galvanometers. With the galvanometers nulled, the
speed relationships of master and slave pulses,
potentiometer calibration gives a direct readout
under test specifications, by setting the selector
switches for a particular test.
of amplifier gain. This circuit avoids inaccuracies
