TASK 71-52-45-700-303 Exhaust Gas Temperature (EGT) Wiring Harness - Test, Testing-002 (Pre SBE 77-0015)

DMC:V2500-A0-71-52-4500-02A-340A-C|Issue No:001.00|Issue Date:2021-02-01

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 71-52-45-700-303 Exhaust Gas Temperature (EGT) Wiring Harness - Test, Testing-002 (Pre SBE 77-0015)

Effectivity

FIG/ITEM

PART NO.

01-005

2A4337

General

Fig/item numbers in parentheses in the procedure agree with those used in the IPC.

Preliminary Requirements

Pre-Conditions

NONE

Support Equipment

NameManufacturerPart Number / IdentificationQuantityRemark
Megohmmeter - model 1620-CLOCALMegohmmeter - model 1620-C
Multimeter keithley model 177LOCALMultimeter keithley model 177

Consumables, Materials and Expendables

NONE

Spares

NONE

Safety Requirements

NONE

Procedure

    1. SUBTASK 71-52-45-750-061 Disconnect the EGT Harness

    1. Refer to Figure and Figure.

    2. Remove the two alumel (larger) nuts and washers and the two chromel (smaller) nuts and washers which attach the harness lugs to the thermocouple terminals.

    3. Remove the harness lugs from the thermocouple terminals.

    4. Install the washers and nuts back on the thermocouple terminals.

    5. Do these steps at the four thermocouple locations.

      6. WARNING

        USE PROTECTIVE GOGGLES AND GLOVES WHEN YOU REMOVE OR INSTALL LOCKWIRE. EACH TIME YOU CUT LOCKWIRE, REMOVE AND DISCARD IT IMMEDIATELY. LOOSE LOCKWIRE CAN CUT YOU OR MAKE YOU BLIND, AND/OR CAN CAUSE DAMAGE.

        Disconnect harness from the junction box terminals.

      1. Cut and discard the lockwire and remove the screws which secure the junction box cover. Remove the cover.

      2. Remove the nuts which secure the lugs of the harness to the junction box terminals. Remove the harness lugs from the junction box terminals.

      3. Cuts and discard the lockwire and remove the screws which secure the harness clamps. Remove the clamps.

    2. SUBTASK 71-52-45-750-062 Continuity Test of EGT Wiring Harness

    1. Refer to Figure and Figure.

      NOTE

      The Multimeter keithley model 177 (or equivalent) and the test leads must be in good condition. The dry cells must be in a condition to give full scale movement for all the positions of the range switch. Make sure that the pin jacks are tight.

      NOTE

      Small movements of the harness during the test must not cause the needle to change. This can be a sign of broken wires.

      ACTION

      RESULT

      1. Set the Multimeter keithley model 177 or equivalent to the range that has a center scale value of approximately 10 ohms.

      2. Do the continuity test of the EGT harness from each thermocouple to the junction box. If you bend the wire, the resistance value changes, reject the harness.

      The resistance value must be between 0 ohms and 10 ohms.

      NOTE

      There are four thermocouple locations with four leads at each location, which means that sixteen measurements are necessary.

      3. If the meter shows a high resistance value, reject the harness.

      Resistance value above 10 ohms.

    3. SUBTASK 71-52-45-750-063 Test of the EGT Harness for Short Circuits

    1. Refer to Figure.

      NOTE

      Small movements of the harness during the tests must not cause the meter to move to below one megohm. This can be a sign of a defect and you must reject the harness.

      ACTION

      RESULT

      1. Set the Megohmmeter - model 1620-C or equivalent to the 100 volts DC scale.

      2. Put one lead of the meter in contact with the chromel harness lug by the A circuit. Put the second lead in contact with the alumel harness lug of the A circuit.

      A resistance value of more than one megohm must show.

      3. Put the second lead in contact with the chromel harness lug of the B circuit.

      A resistance value of more than one megohm must show.

      4. Put the second lead in contact with the alumel harness lug of the B circuit.

      A resistance value of more than one megohm must show.

      5. Put one lead of the meter in contact with the alumel harness lug of the A circuit. Put the second lead in contact with the chromel harness lug of the B circuit.

      A resistance value of more than one megohm must show.

      6. Put the second lead of the meter in contact with the alumel harness lug for the B circuit.

      A resistance value of more than one megohm must show.

      7. Put one lead of the meter in contact with the chromel harness lug of the B circuit. Put the second lead in contact with the alumel harness lug of the B circuit.

      A resistance value of more than one megohm must show.

      8. If the resistance value shown is less than one megohm or 0 ohm in one of these tests, reject the harness.

    4. SUBTASK 71-52-45-750-064 Insulation Resistance Test for EGT Wiring Harness and Junction Box

    1. Refer to Figure, Figure, and Figure.

      Action

      RESULT

      1. Set the Megohmmeter - model 1620-C or equivalent to the 100 VDC scale.

      2. Put one lead of the meter in contact with the external steel braid of the each harness lead. Put the other lead in contact with each of the output lugs of the junction box end of the harness.

      A resistance value of more than one megohm must show.

      3. If the resistance value shown is less than one megohm, correct or repair the harness.

      NOTE

      The harness and junction box can absorb or trap moisture after water wash or an overnight in wet/humid conditions. High humidity can cause insulation resistance to read low. If insulation resistance reads low, you can apply hot air or nitrogen to correct this condition or the harness can be restored by the bake procedure in the vendor CMM.

      4. Do the test of the resistance between each junction box terminal stud and the junction box base.

      NOTE

      Do not touch the insulation with the instrument probe.

      A resistance value of more than one megohm must show.

      5. If the resistance value is less than one megohm, reject the harness.

      NOTE

      The harness and junction box can absorb or trap moisture after water wash or an overnight in wet/humid conditions. High humidity can cause insulation resistance to read low. If insulation resistance reads low, you can apply hot air or nitrogen to correct this condition or the harness can be restored by the bake procedure in the vendor CMM.

      6. Do the test of the resistance between each separator band and the external steel braid of each circuit.

      A resistance value of more than one megohm must show.

      7. If the resistance value shown is less than one megohm, correct or repair the harness.

      NOTE

      The harness and junction box can absorb or trap moisture after water wash or an overnight in wet/humid conditions cause insulation resistance to read low. If insulation resistance reads low, you can apply hot air or nitrogen to correct this condition or the High humidity harness can be restored by the bake procedure in the vendor CMM.

      8. Do the test of the resistance between the lug and the band separator of each circuit.

      A resistance value of more than one megohm must show.

      9. If the resistance value shown is less than one megohm, correct or repair the harness.

      NOTE

      The harness and junction box can absorb or trap moisture after water wash or an overnight in wet/humid conditions. High humidity can cause insulation resistance to read low. If insulation resistance reads low, you can apply HOT AIR SOURCE or NITROGEN COMPRESSED SOURCE - GROUND to correct this condition, or the harness can be restored by the bake procedure in the vendor CMM.

    5. Figure: Thermocouple Locations

    Thermocouple Locations

    Figure: EGT Harness And Junction Box

    EGT Harness And Junction Box

    Figure: EGT Harness And Junction Box Continuity Test

    EGT Harness And Junction Box Continuity Test

    Figure: EGT Harness And Junction Box - Drip Loop Connection To The Junction Box

    EGT Harness And Junction Box - Drip Loop Connection To The Junction Box

    Figure: EGT Harness And Junction Box - Short Circuit Test

    EGT Harness And Junction Box - Short Circuit Test

    Figure: EGT Harness And Junction Box - Insulation Resistance Test

    EGT Harness And Junction Box - Insulation Resistance Test

    Figure: EGT Harness

    EGT Harness

    Figure: EGT Junction Box

    EGT Junction Box

Requirements After Job Completion

Follow-On Conditions

NONE
Change Type:

Added new repair. (19VC705)

Manufacturer Code:LOCAL
Enterprise Name:LOCALLY SUPPLIED
Manufacturer Code:LOCAL
Tool Number:Megohmmeter - model 1620-C
Tool Name:Megohmmeter - model 1620-C
Manufacturer Code:LOCAL
Tool Number:Multimeter keithley model 177
Tool Name:Multimeter keithley model 177