Export Control
EAR Export Classification: Not subject to the EAR per 15 C.F.R. Chapter 1, Part 734.3(b)(3), except for the following Service Bulletins which are currently published as EAR Export Classification 9E991: SBE70-0992, SBE72-0483, SBE72-0580, SBE72-0588, SBE72-0640, SBE73-0209, SBE80-0024 and SBE80-0025.Copyright
© IAE International Aero Engines AG (2001, 2014 - 2021) The information contained in this document is the property of © IAE International Aero Engines AG and may not be copied or used for any purpose other than that for which it is supplied without the express written authority of © IAE International Aero Engines AG. (This does not preclude use by engine and aircraft operators for normal instructional, maintenance or overhaul purposes.).Applicability
All
Common Information
TASK 77-21-15-700-401 EGT Thermocouple - Related Parts - Do a Test on The EGT Thermocouple, Testing-001
General
Fig/Item numbers in parentheses in the procedure agree with those used in the IPC.
Preliminary Requirements
Pre-Conditions
NONESupport Equipment
| Name | Manufacturer | Part Number / Identification | Quantity | Remark |
|---|---|---|---|---|
| Mega-ohmmeter | LOCAL | Mega-ohmmeter | ||
| Wheatstone bridge | LOCAL | |||
| Oven | LOCAL |
Consumables, Materials and Expendables
NONESpares
NONESafety Requirements
NONEProcedure
Refer to Figure.
Set the Wheatstone bridge to zero.
Connect one of the leads to the alumel stud (larger diameter).
Connect the other lead to the chromel stud.
Measure and make a record of the resistance.
Switch the leads.
Measure and make a record of the resistance.
Connect the Wheatstone bridge to the terminal studs of A circuit, with the test leads.
NOTE
Make sure you calibrate the Wheatstone bridge so it is accurate at three decimal places and at low values of resistance.We recommend that you use the clamp on the style probes for accurate measurement.Get the average value of the two measurements. Between 15 deg C and 25 deg C (58 deg F and 77 deg F), the average value must be between 1.03 ohms and 1.53 ohms. If the average values are not in limits, reject the probe.
NOTE
For every degree centigrade that the thermocouple is above or below 20 deg C (68 deg F), the value must be corrected by the subtraction or addition of 0.05 percent.
SUBTASK 77-21-15-750-051 Do a Loop Resistance Test on the EGT Thermocouple
Refer to Figure.
Set the Mega-ohmmeter to the 100 VDC scale.
Do a test for the insulation resistance between A circuit and the thermocouple casing.
Do a test for insulation resistance between B circuit and the thermocouple casing.
Do a test for the insulation resistance between A circuit and B circuit.
Do a test of all circuits against each other and against non-circuit components.
Set the temperature of the Oven to 216 deg F - 250 deg F (102 deg C - 121 deg C).
Put the Thermocouple in the Oven for two hours.
Remove the Thermocouple from the Oven.
Let the temperature of the Thermocouple decrease to room temperature.
If the resistance value is less than 100K ohms for any of the tests, attempt to remove potential moisture from the Thermocouple:
If the resistance value is less than 100K ohms, for any of the test, reject the EGT thermocouple.
SUBTASK 77-21-15-750-052 Do an Insulation Resistance Test on the EGT Thermocouple
Figure: EGT Thermocouple Testing
EGT Thermocouple Testing
