Coat the Mounting Plate Stud Heads Insulation Material of Exhaust Gas Temperature (EGT) Junction Box (VRS3815) [IAE]

TASK 77-21-43-300-802-A
Coat the Mounting Plate Stud Heads Insulation Material of Exhaust Gas Temperature (EGT) Junction Box (VRS3815)

1. Reason for the Job
This task is to coat the insulation material of the four stud heads of the mounting plate (PN HDB18667) which is installed on the base plate of the Exhaust Gas Temperature (EGT) junction box.

NOTE: This repair can be done only one time. If VRS3815 was done before the problem continues, return the EGT junction box to the vendor for repair.

NOTE: If VRS3815 was done before, "VRS3815" will be marked adjacent to the mounting plate (PN HDB18667) part number marking.

NOTE: EGT harness and junction box assembly must be removed from the engine to do this repair.

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 1M(3 FT)
No specific	1	BRUSH - NON METALLIC
No specific	1	HOT AIR SOURCE
No specific	1	NITROGEN COMPRESSED SOURCE - GROUND
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 30.8 and 25.2 lbf.in (0.35 and 0.28 m.daN )

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.V02-127)	lockwire

C. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
FOR [1000EM1] (ENGINE-1)
437AL, 438AR, 451AL, 452AR
FOR [1000EM2] (ENGINE-2)
447AL, 448AR, 461AL, 462AR

D. Referenced Information

REFERENCE	DESIGNATION
TASK 70-23-11-911-013-A	General Torque Tightening Techniques
TASK 71-13-00-010-010-A	Opening of the Fan Cowls 437AL(447AL),438AR(448AR)
TASK 71-13-00-410-010-A	Closing of the Fan Cowls 437AL(447AL),438AR(448AR)
TASK 77-21-43-000-010-B	Removal of the Exhaust Gas Temperature (EGT) Harness and Junction Box (PRE SB 77-0015 and POST SB 77-0015)
TASK 77-21-43-400-010-B	Installation of the Exhaust Gas Temperature (EGT) Harness and Junction Box (PRE SB 77-0015 and POST SB 77-0015)
TASK 78-30-00-040-012-A	Deactivation of the Thrust Reverser Hydraulic Control Unit (HCU) for Ground Maintenance
TASK 78-30-00-440-012-A	Re-activation of the Thrust Reverser Hydraulic Control Unit (HCU) after Ground Maintenance
TASK 78-32-00-010-010-A	Opening of the Thrust Reverser Halves
TASK 78-32-00-410-010-A	Closing of the Thrust Reverser Halves
EGT Harness and Junction Box Assembly
Coat the Insulation Material of the Four Stud Heads

3. Job Set-up
Subtask 77-21-43-941-059-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) On the center pedestal, on ENG panel 115VU:
(a) Put a WARNING NOTICE(S) in position to tell persons not to start the engine.
(2) Make sure that the engine 1(2) shutdown occurred not less than five minutes before you do this procedure.
(3) On overhead maintenance panel 50VU, on the ENG section:
(a) Make sure that the ON legend of the FADEC GND PWR 1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) in position to tell persons not to energize the FADEC 1(2).

Subtask 77-21-43-010-070-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the fan cowls (Ref. AMM TASK 71-13-00-010-010):
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(2) Put the ACCESS PLATFORM 1M(3 FT) in position.

Subtask 77-21-43-040-061-A ** ON A/C NOT FOR ALL

C. Deactivate the Thrust Reverser

WARNING: MAKE SURE THAT THE THRUST REVERSER HYDRAULIC CONTROL UNIT (HCU) IS DEACTIVATED BEFORE YOU DO WORK ON OR AROUND THE THRUST REVERSER. IF THE HCU IS NOT DEACTIVATED, THERE IS A RISK OF UNWANTED THRUST REVERSER OPERATION WHICH CAN CAUSE INJURY TO PERSONS AND/OR DAMAGE TO EQUIPMENT.

(1) Deactivate the thrust reverser Hydraulic Control Unit (HCU) (Ref. AMM TASK 78-30-00-040-012).

Subtask 77-21-43-010-071-A ** ON A/C NOT FOR ALL

D. Open the thrust reverser halves (Ref. AMM TASK 78-32-00-010-010):
(1) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(2) FOR [1000EM2] (ENGINE-2)
461AL 462AR

4. Procedure
Subtask 77-21-43-020-053-A ** ON A/C NOT FOR ALL

A. Disconnect the EGT harness and junction box (11) from the engine (Ref. AMM TASK 77-21-43-000-010).

EGT Harness and Junction Box Assembly ** ON A/C NOT FOR ALL

Subtask 77-21-43-020-054-A ** ON A/C NOT FOR ALL

B. Disconnection of the mounting plate (19), PN HDB18667, from the EGT harness and junction box assembly (11):

EGT Harness and Junction Box Assembly ** ON A/C NOT FOR ALL

Coat the Insulation Material of the Four Stud Heads ** ON A/C NOT FOR ALL

(1) Remove the four nuts (15) which attach the EGT harness to the junction box terminals.

EGT Harness and Junction Box Assembly ** ON A/C NOT FOR ALL

(2) Remove the EGT harness lugs from the junction box terminals.
(3) Removal of the lockwire:

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.

(a) Remove the lockwire and the four screws (18) which attach the mounting plate (19), PN HDB18667 to the base plate (20).

Coat the Insulation Material of the Four Stud Heads ** ON A/C NOT FOR ALL

(4) Remove the mounting plate (19), PN HDB18667.

Subtask 77-21-43-350-052-A ** ON A/C NOT FOR ALL

C. Dry the mounting plate (19) and do a resistance check.

Coat the Insulation Material of the Four Stud Heads ** ON A/C NOT FOR ALL

NOTE: It is recommended to dry the mounting plate (19) before resistance check and coating.

(1) If moisture was found in the mounting plate (19), use a HOT AIR SOURCE or NITROGEN COMPRESSED SOURCE - GROUND and apply hot air or nitrogen to the area. If this did not correct the issue, put the mounting plate (19) in an oven and keep it at 225 deg.F (107.22 deg.C) - 250 deg.F (121.11 deg.C) for one hour.
(2) Do a resistance check between the mounting plate base and the four stud threads, each individually. The resistance must be more than 100,000 ohms. If the resistance check is more than 100,000 ohms, go to Para. 4.D.
(3) If the resistance is below 100,000 ohms, this repair should not be done. Return the part to the vendor for repair.

Subtask 77-21-43-350-053-A ** ON A/C NOT FOR ALL

D. Coat the insulation material of the four stud heads located on the back of the mounting plate (19), PN HDB18667.

Coat the Insulation Material of the Four Stud Heads ** ON A/C NOT FOR ALL

CAUTION: DO NOT USE WET CLEANING METHODS TO CLEAN THE INSULATION MATERIAL.

(1) Dry clean the insulation material of the four stud heads on the back of mounting plate (19), PN HDB18667. It is permitted to use dry compressed air for cleaning.

NOTE: The insulation material must be fully dry before coating.

(2) Apply a coat of duraseal+ 1529 FS to the dry insulation material of the four stud heads. Use a BRUSH - NON METALLIC to apply the coating.
(3) Air dry the coating for two hours at room temperature.
(4) Cure the coating in an oven for two hours at 400 deg.F (204.44 deg.C) - 450 deg.F (232.22 deg.C).
(5) Mark the mounting plate (19), PN HDB18667 with "VRS3815" adjacent to the part number marking. Use the vibropeen method for marking.
(6) If necessary, dry clean the mounting plate (19), PN HDB18667. It is permitted to use dry compressed air for cleaning.

Subtask 77-21-43-420-053-A ** ON A/C NOT FOR ALL

E. Install the mounting plate (19), PN HDB18667 on the EGT harness and junction box assembly (11).

Coat the Insulation Material of the Four Stud Heads ** ON A/C NOT FOR ALL

(1) Place the mounting plate (19), PN HDB18667 on the base plate (20) and align the screw holes.
(2) Secure the mounting plate (19), PN HDB18667 with four screws (18).
(3) TORQUE the screws (18) to between 30.8 and 25.2 lbf.in (0.35 and 0.28 m.daN )

(Ref. AMM TASK 70-23-11-911-013).
(4) Safety the screws:

(a) Safety the screws (18) with lockwire (Material No.V02-127) .

Subtask 77-21-43-420-054-A ** ON A/C NOT FOR ALL

F. Install the EGT harness and junction box (11) to the engine (Ref. AMM TASK 77-21-43-400-010).

5. Close-up
Subtask 77-21-43-410-065-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Remove the access platform(s).
(3) Close the thrust reverser halves (Ref. AMM TASK 78-32-00-410-010):
(a) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(b) FOR [1000EM2] (ENGINE-2)
461AL 462AR

Subtask 77-21-43-440-057-A ** ON A/C NOT FOR ALL

B. Activate the thrust reverser HCU (Ref. AMM TASK 78-30-00-440-012).

Subtask 77-21-43-410-066-A ** ON A/C NOT FOR ALL

C. Close Access
(1) Close the fan cowls (Ref. AMM TASK 71-13-00-410-010):
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(2) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 03:18:23 UTC