TM 55-2840-231-23
4-3. Thermocouple Assembly - Inspection
INITIAL SETUP
Applicable
Configuration
References
All
TM 55-4920-244-14
ENGINE/
Themocouple
When erroneous temperature inspections are
suspected, insure that the indicating system
is functioning properly. Perform a TOT gage
calibration check and a total TOT circuit
resistance check. (Refer to TM
55-4920-244-14 and applicable airflame
manuals.) If no discrepancies are noted,
check the thermocouple system as follows. Do
not remove the thermocouple assembly from
the engine.
NOTE
A check of these limits can be
performed only by using test
instruments that offer usable
sensitivity in this range (null-type
resistance bridge). lf such
instrumentation is not available,
an ohm meter (Simpson meter or
equivalent) can be used to detect
an open circuit. (An open circuit
wiII cause a high resistance; a
short circuit wiII cause it to be
low).
a. Visually inspect
thermocouple assembly for
broken leads, loose
terminals and other visible
damage.
b. Disconnect plug P12
from receptacle at the
engine deck.
c. Measure the internal
resistance of the
thermocouple harness at
the terminal block on the
right-hand side of the
exhaust collector.
Resistance shall be 0.55 to
0.65 ohms.
d. Reconnect plug P12.
Reconnect leads to the
terminal assembly. Ensure
that the connector is
properly mated and secure.
4-
2
Change 13
