5-12. Checkout of Position Transmitters.
The IGV and throttle position transmitters provided in
the engine accessories may not be electrically isolated
from the system and individually checked. These
components are synchronous instrumentation and must
be checked while installed in a system or functional
loop. (See figure FO-22 located in the back of the
manual.) Refer to paragraph 5-38 for troubleshooting
information on the IGV and throttle position transmitters.
5-13. Checkout of Thermocouples.
Thermocouple checkout consists only of a continuity
check; however, if a thermocouple is suspected of being
defective the unit may be removed from the system and
a like part number thermocouple may be connected.
thermocouples for some engines.
5-14. Checkout of Vibration Pickups.
The vibration pickup may be lightly tapped, when
electrically connected, to provide a response on the
vibration meter in the control cab. The pickups provided
in the engine accessories may be interchanged by
substitution for fault isolation during daily checkout, if
the same part number is substituted.
5-15. Pressure Gage Switch Checkout.
Pressure gage switches (170, 181, 184C, figure 7-24)
may be functionally checked without removal from the
data acquisition assembly. Check the actuation of each
pressure gage switch on increasing and decreasing
pressures in accordance with the following:
a. Connect a pressure hose with appropriate
connectors to the test trailer suspect pressure switch on
the data acquisition box, Unit 11.
b. Turn the SERVICES AIR switch to ON, and slowly
adjust the Pressure Regulator while watching the
pressure gage, (all on panel 9A2). Verify that the
indicator light associated with the pressure switch
activates on or off as the case may be, at the specified
c. Substitute cabling by switching connections at the
back of the switches, to verify lead defects, and applying
pressure as above.
d. Pressure switches S1, S2, and S3 shall actuate as
Low Fuel Pressure, indicator light (Panel 4A1)
extinguishes at pressure above 8.0 PSI.
Engine Low Oil Pressure, indicator light (Panel
4A1) extinguishes at pressure above 30 PSI.
Hot Air Pressure, activates the DE-ICE VALVE
OPEN, and DE-ICE VALVE CLOSED lights on
operators panel 3A3. The CLOSED light should
be ON for all engines except the T-73. With a
pressure of approximately 4.5 PSI the CLOSED
light should extinguish and the OPEN light will
e. If any pressure gage switch does not actuate on
both increasing and decreasing pressures within the
specified limits for each unit, depressurize the test
setup, remove the defective switch, then install a new
unit. Check the actuation of the replacement unit on
both increasing and decreasing pressures as outlined in
the foregoing instructions.
f. After functional check of the pressure gage
switches, depressurize and dismantle and test setup.
Reconnect the electrical system connectors to the
respective pressure gage switches and install the
removed dust caps on the quick-disconnect couplers.
5-16. Warning Circuit Checkout Procedures.
This paragraph contains the procedures required to
check the METS warning circuits on a periodic basis.
Proceed as follows:
a. With the electrical system energized and the
specified warmup accomplished, depress and hold the
TEST switchlight unit (26, figure 1-25) located on
services panel 4A1. Verify that the entire ALARM
DISPLAY intermittently flashes on and off and the
audible alarm sounds continuously.
b. With the TEST switchlight unit depressed, depress
and release the ACK switchlight unit (25). Verify that all
ALARM DISPLAY indicators come on and stay on and
that the audible alarm ceases to sound. If any of the
alarm lights fail to come on, the problem will be in the
alarm card in the Alarm Monitor unit 4A2. Refer to the
troubleshooting, table 5-4, or the alarm verification
tables for alarm card identification. Each card contains
two separate channels, and each channel functions
independently. Four spare cards are available within
the alarm monitor unit 4A2 for substitution.