Resistance Check of the Return Ground Connections - Cabin Pressure Controller (CPC) 1 (11HL) and 2 (12HL) and the Electronic Modules 10HL-1 and 10HL-2

TASK 21-31-00-760-001-A
Resistance Check of the Return Ground Connections - Cabin Pressure Controller (CPC) 1 (11HL) and 2 (12HL) and the Electronic Modules 10HL-1 and 10HL-2

ZONE: 120
ZONE: 160
FIN: 10HL
FIN: 11HL
FIN: 12HL

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	2	ACCESS PLATFORM 1M(3 FT)
No specific	2	ACCESS PLATFORM 2M (6 FT)
No specific	1	MILLIOHMMETER 0.01 OHM - LOW VOLTAGE
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.04TMB2)	Varnish-- Electrical Bonding Structure
(Material No.06AAA1)	Polysulfide Sealant_General Purpose Brushable -
FOR [11HL] (PRESS CONT 1)
(Material No.04TMB2)	Varnish-- Electrical Bonding Structure
(Material No.06AAA1)	Polysulfide Sealant_General Purpose Brushable -
FOR [12HL] (PRESS CONT 2)
(Material No.04TMB2)	Varnish-- Electrical Bonding Structure
(Material No.06AAA1)	Polysulfide Sealant_General Purpose Brushable -

C. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
120	AVIONICS COMPARTMENT
160	BULK CARGO COMPARTMENT AFT BULKHEAD OF AFT CARGO COMPARTMENT TO AFT BULKHEAD OF BULK CARGO COMPARTMENT
162DW, 811, 826

D. Referenced Information

REFERENCE	DESIGNATION
TASK 20-28-00-912-802-A	Electrical Bonding - General Maintenance Procedure
TASK 21-31-00-710-002-A	Operational Test of the Pressure Control and Monitoring
TASK 21-31-34-000-001-A	Removal of the Cabin Pressure Controller (CPC)
TASK 21-31-34-400-001-A	Installation of the Cabin Pressure Controller (CPC)
TASK 21-31-51-000-002-A	Removal of the Outflow Valve - Electronics Module 10HL-1 (10HL-2)
TASK 21-31-51-000-005-A	Removal of the Outflow Valve - Feedback Assembly 10HL-6
TASK 21-31-51-400-002-A	Installation of the Outflow Valve - Electronics Module 10HL-1 (10HL-2)
TASK 21-31-51-400-005-A	Installation of the Outflow Valve - Feedback Assembly 10HL-6
TASK 24-41-00-861-002-A	Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01	Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 24-41-00-862-002-A	De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01	De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02	De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
TASK 25-55-12-000-001-A	Removal of the Aft Cargo-Compartment Partition at FR65
TASK 25-55-12-400-001-A	Installation of the Aft Cargo-Compartment Partition at FR65
TASK 52-30-00-860-001-A	Open the FWD or Aft Cargo-Compartment Door with the Yellow Electric Pump
TASK 52-30-00-860-002-A	Close the FWD or Aft Cargo-Compartment Door with the Yellow Electric Pump
Return Ground Connections - Earthing Points
FOR [11HL] (PRESS CONT 1)
TASK 20-28-00-912-802-A	Electrical Bonding - General Maintenance Procedure
Return Ground Connections - Earthing Points
FOR [12HL] (PRESS CONT 2)
TASK 20-28-00-912-802-A	Electrical Bonding - General Maintenance Procedure
Return Ground Connections - Earthing Points

3. Job Set-up
Subtask 21-31-00-480-055-A

A. Measurement Equipment
(1) MILLIOHMMETER 0.01 OHM - LOW VOLTAGE with the related leads and probes.

Subtask 21-31-00-861-063-A

B. Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002)

Subtask 21-31-00-010-057-A

C. Get Access
(1) Put the ACCESS PLATFORM 1M(3 FT) in position at the access door 811.
(2) Open the access door 811.
(3) Open the AFT cargo-compartment door 826 (Ref. AMM TASK 52-30-00-860-001).
(4) Put the ACCESS PLATFORM 2M (6 FT) in position at the AFT cargo-compartment door 826.
(5) Remove the access panel 162DW (Ref. AMM TASK 25-55-12-000-001).

Subtask 21-31-00-865-063-A

D. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AIR COND/CAB/PRESS/CTL1	1HL	D09
** ON A/C NOT FOR ALL
122VU	AIR COND/AFT CARGO VENT/FAN	30HN	S22
** ON A/C ALL
122VU	AIR COND/LAV/GALLEY VENT CTL/EXTRACT FAN/SPLY	6HU	U19
122VU	AIR COND/CAB PRESS/CTL/MAN	3HL	Y23
122VU	AIR COND/CAB PRESS/CTL/2	2HL	Y22

Subtask 21-31-00-020-052-A

E. Removal and Disconnection of the Applicable Components
(1) Remove the cabin pressure controllers 1 (11HL) and 2 (12HL) (Ref. AMM TASK 21-31-34-000-001).

NOTE: It is not necessary to remove the cabin pressure controllers from the aircraft.

(2) Disconnect the electrical connectors 10HL-A and 10HL-B from the electronic modules 10HL-1 and 10HL-2 (Ref. AMM TASK 21-31-51-000-002).
(3) Disconnect the electrical connectors 10HL-D and 10HL-E from the feedback assembly 10HL-6 (Ref. AMM TASK 21-31-51-000-005).

4. Procedure
Subtask 21-31-00-760-050-A

A. Measure the Resistance

NOTE: Maximum Allowed Resistance Value
The maximum resistance value at all measurement points should not be more than 300 milliohms.

(1) Connect the measurement equipment (refer to the manufacturers instructions) to:
(a) FOR [11HL] (PRESS CONT 1)

the pin 2 on the electrical connector 11HL-AC and a good conductive surface on the aircraft structure.

measure the resistance value and make sure that it is not more than the maximum allowed value.
you must do the bonding of the bonding point 6587VN/DC1 (Ref. AMM TASK 20-28-00-912-802) if the resistance value is more than the allowed value.

NOTE: For this application, when you do the bonding you must:

apply the Polysulfide Sealant_General Purpose Brushable - (Material No.06AAA1) to the necessary areas and allow it to fully dry then,
apply the Varnish-- Electrical Bonding Structure (Material No.04TMB2) to the areas of the dried sealant.

Return Ground Connections - Earthing Points

(b) FOR [12HL] (PRESS CONT 2)

the pin 2 on the electrical connector 12HL-AC and a good conductive surface on the aircraft structure.

measure the resistance value and make sure that it is not more than the maximum allowed value.
you must do the bonding of the bonding point 6582VN/DC2 (Ref. AMM TASK 20-28-00-912-802) if the resistance value is more than the allowed value.

NOTE: For this application, when you do the bonding you must:

apply the Polysulfide Sealant_General Purpose Brushable - (Material No.06AAA1) to the necessary areas and allow it to fully dry then,
apply the Varnish-- Electrical Bonding Structure (Material No.04TMB2) to the areas of the dried sealant.

Return Ground Connections - Earthing Points

(c) For the electronics module (10HL-1)
1 the pin J on the electrical connector 10HL-A and a good conductive surface on the aircraft structure.

measure the resistance value and make sure that it is not more than the maximum allowed value.
you must do the bonding of the bonding point 6587VN/DC1 (Ref. AMM TASK 20-28-00-912-802) if the resistance value is more than the allowed value.

NOTE: For this application, when you do the bonding you must:

apply the Polysulfide Sealant_General Purpose Brushable - (Material No.06AAA1) to the necessary areas and allow it to fully dry then,
apply the Varnish-- Electrical Bonding Structure (Material No.04TMB2) to the areas of the dried sealant.

2 the pin J on the electrical connector 10HL-D and a good conductive surface on the aircraft structure.

measure the resistance value and make sure that it is not more than the maximum allowed value.
you must do the bonding of the bonding point 6587VN/DC1 (Ref. AMM TASK 20-28-00-912-802) if the resistance value is more than the allowed value.

NOTE: For this application, when you do the bonding you must:

apply the Polysulfide Sealant_General Purpose Brushable - (Material No.06AAA1) to the necessary areas and allow it to fully dry then,
apply the Varnish-- Electrical Bonding Structure (Material No.04TMB2) to the areas of the dried sealant.

Return Ground Connections - Earthing Points

(d) For the electronics module (10HL-2)
1 the pin J on the electrical connector 10HL-B and a good conductive surface on the aircraft structure.

measure the resistance value and make sure that it is not more than the maximum allowed value.
you must do the bonding of the bonding point 6582VN/DC2 (Ref. AMM TASK 20-28-00-912-802) if the resistance value is more than the allowed value.

2 the pin H on the electrical connector 10HL-E and a good conductive surface on the aircraft structure.

measure the resistance value and make sure that it is not more than the maximum allowed value.
you must do the bonding of the bonding point 6582VN/DC2 (Ref. AMM TASK 20-28-00-912-802) if the resistance value is more than the allowed value.

NOTE: For this application, when you do the bonding you must:

apply the Polysulfide Sealant_General Purpose Brushable - (Material No.06AAA1) to the necessary areas and allow it to fully dry then,
apply the Varnish-- Electrical Bonding Structure (Material No.04TMB2) to the areas of the dried sealant.

Return Ground Connections - Earthing Points

5. Close-up
Subtask 21-31-00-860-067-A

A. Aircraft Maintenance Configuration
(1) Make sure that:
(a) the ACCESS PLATFORM 1M(3 FT) is in position at the access door 811.
(b) the access door 811 is open.
(c) the AFT cargo-compartment door 826 (Ref. AMM TASK 52-30-00-860-001) is open.
(d) the ACCESS PLATFORM 2M (6 FT) is in position at the AFT cargo-compartment door 826.
(e) the access panel 162DW (Ref. AMM TASK 25-55-12-000-001) is removed.

Subtask 21-31-00-865-064-A

B. Make sure that this(these) circuit breaker(s) is(are) open, safetied and tagged:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AIR COND/CAB/PRESS/CTL1	1HL	D09
** ON A/C NOT FOR ALL
122VU	AIR COND/AFT CARGO VENT/FAN	30HN	S22
** ON A/C ALL
122VU	AIR COND/LAV/GALLEY VENT CTL/EXTRACT FAN/SPLY	6HU	U19
122VU	AIR COND/CAB PRESS/CTL/MAN	3HL	Y23
122VU	AIR COND/CAB PRESS/CTL/2	2HL	Y22

Subtask 21-31-00-420-052-A

C. Installation and Connection of the Applicable Components

NOTE: It is not necessary to do the operational test of the pressure control and monitoring system (Ref. AMM TASK 21-31-00-710-002) at this time.

(1) Install the cabin pressure controllers 1 (11HL) and 2 (12HL) (Ref. AMM TASK 21-31-34-400-001).
(2) Connect the electrical connectors 10HL-A and 10HL-B to the electronic modules 10HL-1 and 10HL-2 (Ref. AMM TASK 21-31-51-400-002).
(3) Connect the electrical connectors 10HL-D and 10HL-E to the feedback assembly 10HL-6 (Ref. AMM TASK 21-31-51-400-005).

Subtask 21-31-00-865-066-A

D. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AIR COND/CAB/PRESS/CTL1	1HL	D09
** ON A/C NOT FOR ALL
122VU	AIR COND/AFT CARGO VENT/FAN	30HN	S22
** ON A/C ALL
122VU	AIR COND/LAV/GALLEY VENT CTL/EXTRACT FAN/SPLY	6HU	U19
122VU	AIR COND/CAB PRESS/CTL/MAN	3HL	Y23
122VU	AIR COND/CAB PRESS/CTL/2	2HL	Y22

Subtask 21-31-00-410-055-A

E. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the access door 811.
(3) Install the access panel 162DW (Ref. AMM TASK 25-55-12-400-001).
(4) Remove the access platform(s).
(5) Close the AFT cargo-compartment door 826 (Ref. AMM TASK 52-30-00-860-002).

Subtask 21-31-00-862-060-A

F. De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).

[Rev.10 from 2021] 2026.04.02 06:11:14 UTC