Fuel Quantity - Dualcomp 53QT, Left Wing Tank

TASK 28-42-00-810-829-A
Fuel Quantity - Dualcomp 53QT, Left Wing Tank

WARNING: OBEY THE FUEL SAFETY PROCEDURES.

WARNING: WHEN YOU DO WORK ON THE FUEL SYSTEM WIRING, YOU MUST USE TEST EQUIPMENT THAT IS APPROVED (REFER TO INTERNATIONAL OR NATIONAL SPECIFICATIONS FOR INTRINSICALLY SAFE TEST EQUIPMENT: EN50020, UL913 OR EQUIVALENT). TEST EQUIPMENT THAT IS NOT APPROVED CAN CAUSE FIRE OR AN EXPLOSION.

1. Possible Causes

FQIC [3QT]
aircraft wiring
fused connector 4041VC-A
fused connector 4043VC-A
water contamination
microbiological contamination
unwanted material
HARNESS-LEFT WING TANK A [57QT]
HARNESS-LEFT WING TANK B [63QT]
DUALCOMP-RIB 2-3, L WNG TK GROUP B [53QT]
Fused connectors 4041VC-A and 4043VC-A
HARNESS-CHAN A, L WING TK INR [13QT1]
HARNESS-CHAN B, L WING TK INR [14QT1]

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

REFERENCE	QTY	DESIGNATION
No specific	AR	MULTIMETER - STANDARD

B. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 28-11-00-810-809-A	Fuel - Unwanted Material (Debris) In The Left (Right) Wing-Tank (Outboard of the Rib2)
TSM TASK 28-42-00-810-879-A	The Fuel Quantity Indications Go Inoperative Or Degraded Associated With Multiple Fuel Probe Failures Due To Water & Microbiological Contamination
AMM 12-11-28-650-003	Pressure Refuel with Automatic Control
AMM 12-32-28-281-001	Drain Water Content
AMM 12-32-28-281-003	Sample Fuel for Microbiological Contamination Analysis
ESPM 2052210
ESPM 2052220
ESPM 2053210
AMM 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
AMM 24-41-00-862-002	De-energize the Aircraft Electrical Circuits Supplied from the External Power
AMM 28-10-00-910-001	Safety Procedures When You Do Work in a Fuel Tank
AMM 28-10-00-910-002	Access to the Fuel Tanks and the Work Areas
AMM 28-11-00-600-003	Removal of Microbiological Particles
AMM 28-25-00-869-001	Fuel Transfer
AMM 28-42-00-00-
AMM 28-42-00-740-003	Interrogation of the FQIS Input Parameters Pages
AMM 28-42-00-740-009	Interrogation of the (SIMMONDS/GOODRICH) FQIS Trouble Shooting Data
ASM 284205
AWM 284205
ASM 284207
AWM 284211
AWM 284213
CMM 284223
AMM 28-42-34-000-001	Removal of the Fuel Quantity-Indicating Computer (FQIC)
AMM 28-42-34-400-001	Installation of the Fuel Quantity-Indicating Computer (FQIC)
AMM 28-42-43-000-005	Removal of the Wing Tank Harness
AMM 28-42-43-000-006	Removal of the Wing-Tank Inner-Cell Group A Harness
AMM 28-42-43-000-007	Removal of the Wing-Tank Inner-Cell Group B Harness
AMM 28-42-43-000-008	Removal of the Wing Tank Fuel Quantity Indicating Probe Fused/Shorting Plug Connectors
AMM 28-42-43-400-005	Installation of the Wing Tank Harness
AMM 28-42-43-400-006	Installation of the Wing-Tank Inner-Cell Group A Harness
AMM 28-42-43-400-007	Installation of the Wing-Tank Inner-Cell Group B Harness
AMM 28-42-43-400-008	Installation of the Wing Tank Fuel Quantity Indicating Probe Fused/Shorting Plug Connectors
AMM 28-42-46-000-001	Removal of the Dualcomp
AMM 28-42-46-400-001	Installation of the Dualcomp
AMM 31-32-00-860-001	Procedure to Get Access to the SYSTEM REPORT/TEST Menu Page
AMM 31-60-00-860-001	EIS Start Procedure
AMM 31-60-00-860-002	EIS Stop Procedure
TSM TASK 28-42-00-03	QUANTITY INDICATING - TASK SUPPORTING DATA

3. Fault Confirmation
Subtask 28-42-00-865-075-A ** ON A/C NOT FOR ALL

A. Table of the circuit breakers used in this procedure:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	FUEL/FQI/CHAN/1	1QT	A13
121VU	FUEL/FQI/CHAN/2	2QT	M27

Subtask 28-42-00-710-078-A ** ON A/C NOT FOR ALL

B. Test

NOTE: The FQIS is a positive DC capacitive system. In such a system the fuel probes (which are the sensors) operate as capacitors. The dielectric of the capacitors is:

fuel if a fuel probe is covered with fuel
air if a fuel probe is not covered with fuel.

Each fuel probe operates as a variable capacitor with a capacitance value related to the ratio of the fuel probe covered in air or fuel. This is because the permittivity of the fuel is approximately two times that of air. Thus the fuel is a component part of the electrical FQIS.

If water (and/or other unwanted materials) gets into a fuel-tank, it can cause problems. Example, it can cause a partial or a complete short circuit between the two concentric tubes of the fuel probe.

It is very important that the water in each fuel tank is kept to a minimum. The procedures given in the MPD and AMM must be fully completed. A failure to do so can cause the problems that follow:

water contamination
microbiological contamination
chemical contamination
local fuel-tank corrosion
engine corrosion
the engine fuel filters to become blocked
the aircraft is out of service for a long period some time in the future while the microbiological contamination is removed
possible aircraft safety issues.

In this procedure the sensor is a dualcomp.
In normal operation the dualcomp stays fully covered (immersed) in fuel because it is installed near the fuel tank floor.
The dualcomp outer protective cover contains the two compensator (capacitor) assemblies and their associated circuitry CMM 284223.
The dualcomp capacitors are the source of the DCMP KA and KB (the dielectric constant (permittivity)) as shown (displayed) on the input parameter page 1 (of the CFDS - FUEL menu).

(1) If you are:

not sure that the AMM refuel and all the MPD scheduled servicing tasks (related to water and microbiological contamination of the fuel) have been correctly done, do the TSM procedure (Ref. TSM TASK 28-42-00-810-879)
sure that the AMM refuel and all the MPD scheduled servicing tasks (related to water and microbiological contamination of the fuel) have been correctly done, do step (2).

(2) To keep the number of computer replacements (with no fault found) to a minimum, do the power on BITE test of the FQIS as follows:

NOTE: The left wing tank must contain 1000Kg (2200lb) of fuel to fully test the dualcomp.

(a) If the FQIS is not energized:
1 Close the C/Bs 1QT and 2QT.
2 Energize the Aircraft Electrical Circuits from the External Power AMM 24-41-00-861-002.
(b) If the FQIS is energized, reset the FQIC as follows:
1 Open the C/Bs 1QT and 2QT.
2 Wait 10 seconds.
3 Close the C/Bs 1QT and 2QT.

NOTE: For the FQIC to do a (new) power up BITE test, a power supply interrupt (interval) of more than 10 seconds is necessary. This gives the current status of the FQIS components.

(3) Do the EIS Start Procedure (ECAM only) AMM 31-60-00-860-001.
(4) On the ECAM control panel, push (in) the FUEL P/BSW.
(5) Make sure that the FUEL page shows on the ECAM lower display unit.
(6) Wait 60 seconds.
(7) Continue as follows:

NOTE: The FUEL page FQIs will show XXs in amber color, for 35 seconds, during the FQIC power up BITE test.
A FQIS sensor fault must be sensed by the FQIC for 60 seconds before the applicable LRU identification is transmitted to the CFDS as unserviceable. The fault message is shown on the MCDU when set to SYSTEM REPORT/TEST (FUEL) and the FQIS STATUS page.

(a) Do the procedure to get access to the SYSTEM REPORT/TEST menu page AMM 31-32-00-860-001.
(b) When the SYSTEM REPORT/TEST menu page comes into view, push the line key adjacent to FUEL.
(c) When the FUEL menu page comes into view, push the line key adjacent to FQIS STATUS.
(8) Examine the FQIS STATUS page.
(a) Make a record of the messages shown (or use the PRINT function to get a copy).
(b) When you have got a copy or print, press the RETURN key on the MCDU.
(c) When the FUEL menu page comes into view, push the line key adjacent to INPUT PARAMETERS.
(9) Examine the INPUT PARAMETER VALUES (page 1 - FQIS INPUT PARAMETERS).
(a) Make a record of the page 1 (or use the PRINT function to get a copy).
(b) When you have got a copy or print, press the NEXT PAGE key on the MCDU.
(10) Examine the INPUT PARAMETERS (page 2 - FQIS PROBE CAPACITANCES).
(a) Make a record of the page 2 (or use the PRINT function to get a copy).
(11) Compare the original failure and your records with those that follow:

if the FQI goes inoperative or degraded and is associated with multiple fuel probe failures, do the procedure (Ref. TSM TASK 28-42-00-810-879)
if multiple fuel probe messages are given on the FQIS STATUS page with multiple values on the I/P PARAMETER page 1 and page 2 (shown with a - (dash) or out of range (see the note below)), do the procedure (Ref. TSM TASK 28-42-00-810-879)
if the message L DUALCOMP 53QT or L DUALCOMP 53QT/WRG is shown (and/or the LEFT DCMP KA and/or KB values on the I/P PARAMETER page 1 and/or the related left wing-tank dualcomp capacitance values on page 2) are shown with a - (dash) or out of range, do Para. 4.A.
if the message L DUALCOMP 53QT or L DUALCOMP 53QT/WRG is not shown and the values shown on the I/P PARAMETER pages are correct, no troubleshooting work steps are necessary.

NOTE: If the input parameter values are calculated (in the FQIC 3QT) they are shown (displayed). This is also true when the parameters are out of range. A - (dash) is shown if a parameter is not measured. Example, because of a fuel-probe sensor detector failure. Out of range values of more than the display capability are shown as the maximum value of the display.

The normal range of fuel-probe capacitance values (at dry and full) can be got from the Tank Units DC Capacitance Values 28-42-00-03 TSM TASK 28-42-00-03.

NOTE: You can get data from the:

Description and Operation (D and O) section of the Aircraft Maintenance Manual (AMM), the Fuel Quantity Indicating System (FQIS) AMM 28-42-00-00-
Trouble-shooting Manual (TSM) - Task Supporting Data (Ref. P. Block 301)
Aircraft Schematic Manual (ASM) ASM 284205 and ASM 284207.

NOTE: You can get more Trouble-shooting data from the CFDS(FUEL):

Input Parameters Page 2 AMM 28-42-00-740-003
FQIC Trouble Shooting Data AMM 28-42-00-740-009.

NOTE: OPTIONAL TESTING:
If a DC Capacitance Fuel System Tester is available, measurements can be taken before a decision is made to go into or close up a fuel tank. The Tester can be connected to the FQIC rack connector or the related tank wall connector. (Ref. P. Block 301 for the Tank Units DC Capacitance Values).

Subtask 28-42-00-710-078-B ** ON A/C NOT FOR ALL

B. Test.

NOTE: The FQIS is a positive DC capacitive system. In such a system the fuel probes (which are the sensors) operate as capacitors. The dielectric of the capacitors is:

Fuel if a fuel probe is covered with fuel
Air if a fuel probe is not covered with fuel.

Water contamination
Microbiological contamination
Chemical contamination
Local fuel-tank corrosion
Engine corrosion
The engine fuel filters to become blocked
The aircraft is out of service for a long period some time in the future while the microbiological contamination is removed
Possible aircraft safety issues.

In this procedure the sensor is a dualcomp.
In normal operation the dualcomp stays fully covered (immersed) in fuel because it is installed near the fuel tank floor.
The dualcomp outer protective cover contains the two compensator (capacitor) assemblies and their associated circuitry CMM 284223.
The dualcomp capacitors are the source of the DCMP K value (the dielectric constant (permittivity)) as shown (displayed) on the input parameter page 1 (of the CFDS - FUEL menu).

(1) If you are:

Not sure that the AMM refuel and all the MPD scheduled servicing tasks (related to water and microbiological contamination of the fuel) have been correctly done, do the TSM procedure (Ref. TSM TASK 28-42-00-810-879)
Sure that the AMM refuel and all the MPD scheduled servicing tasks (related to water and microbiological contamination of the fuel) have been correctly done, do step (2).

(2) To keep the number of computer replacements (with no fault found) to a minimum, do the power on BITE test of the FQIS as follows:

NOTE: The left wing inner cell must contain 1500Kg (3300lb) of fuel to fully test the dualcomp.

NOTE: For the FQIC to do a (new) power up BITE test, a power supply interrupt (interval) of more than 10 seconds is necessary. This gives the current status of the FQIS components.

If the FQI goes inoperative or degraded and is associated with multiple fuel probe failures, do the procedure (Ref. TSM TASK 28-42-00-810-879)
If multiple fuel probe messages are given on the FQIS STATUS page with multiple values on the I/P PARAMETER page 1 and page 2 (shown with a - (dash) or out of range (see the note below)), do the procedure (Ref. TSM TASK 28-42-00-810-879)
If the message L DUALCOMP 53QT or L DUALCOMP 53QT/WRG is shown (and/or DCMP K value on the I/P PARAMETER page 1 and/or the related left wing-tank dualcomp capacitance values on page 2) are shown with a - (dash) or out of range, do Para. 4.A.
If the message L DUALCOMP 53QT or L DUALCOMP 53QT/WRG is not shown and the values shown on the I/P PARAMETER pages are correct, no troubleshooting work steps are necessary.

NOTE: You can get data from the:

Description and Operation (D and O) section of the Aircraft Maintenance Manual (AMM), the Fuel Quantity Indicating System (FQIS) AMM 28-42-00-00-
Trouble-shooting Manual (TSM) - Task Supporting Data (Ref. P. Block 301)
Aircraft Schematic Manual (ASM) ASM 284205 and ASM 284207.

NOTE: You can get more Trouble-shooting data from the CFDS(FUEL):

Input Parameters Page 2 AMM 28-42-00-740-003
FQIC Trouble Shooting Data AMM 28-42-00-740-009.

4. Fault Isolation
Subtask 28-42-00-810-078-A ** ON A/C NOT FOR ALL

A. Procedure

NOTE: The dualcomp 53QT contains two capacitive sensors and their related circuitry. It is located in the left-wing fuel-tank between Ribs 2 and 3. It is mounted on a support bracket, adjacent to the rear spar, just above the fuel tank floor. In normal operation with a fuel load it is fully below the surface of the fuel. The output signals from the dualcomp are DUALCOMP SIGNAL A and DUALCOMP SIGNAL B and are proportional to the dieletric permittivity of the fuel.

(1) Temporarily replace the FQIC 3QT with a serviceable item AMM 28-42-34-000-001 and AMM 28-42-34-400-001.

NOTE: The step (1) has been included because it is important to make sure that the FQIC is serviceable before you start more steps.

(2) If the message L DUALCOMP 53QT or L DUALCOMP 53QT/WRG:

is not shown (and the related input parameter values show correct), complete the installation of the FQIC [3QT] AMM 28-42-34-000-001 and AMM 28-42-34-400-001
is shown (and the related input parameter values stay incorrect), do step (3).

(3) Remove the temporary installed serviceable FQIC 3QT AMM 28-42-34-000-001 and return it to stores.
(4) Get access AMM 28-42-43-000-008 to the:

tank wall connectors 4039VC1-A and 4040VC1-A
fused connectors 4041VC-A and 4043VC-A.

(5) Disconnect the:

tank wall connectors 4039VC1-A and 4040VC1-A
fused connectors 4041VC-A and 4043VC-A.

(6) Do a visual inspection and electrical tests of the aircraft wiring AWM 284205, AWM 284211 and AWM 284213 between the FQIC rack connector 3QT-A and the tank wall connectors 4039VC1-A and 4040VC1-A as follows:

NOTE: Each capacitive fuel probe is supplied with an alternating current drive from the FQIC.
The fuel probes in a tank group (harness) share the drive and drive return (two aircraft wires) between the FQIC rack connector and the connectors 4041VC-A and 4043VC-A.
The connectors 4041VC-A and 4043VC-A are adjacent to and below their related tank wall connectors 4039VC1-A and 4040VC1-A.
In the connectors 4041VC-A and 4043VC-A (shorting plugs):

the drive wire divides to supply each of the related fuel probes, in parallel
the drive return wire also divides to connect to each of the related fuel probes,in parallel. All of the discrete drive and drive return wires then go to the tank wall connectors 4039VC1-A and 4040VC1-A.
Diodes located on a circuit card assembly in the dualcomp half wave rectify the output signals. The positive going, dc current signals (in proportion to the capacitance value/fuel dielectric permittivity) are routed directly from the tank wall connectors 4039VC1-A and 4040VC1-A to the FQIC rack connector.
The drive inputs and signal outputs from:
dualcomp A are routed to the FQIC 3QT through the left wing wiring group A
dualcomp B are routed to the FQIC 3QT through the left wing wiring group B.

(a) Visual Inspection
Make sure that good lighting is available.
Do a visual inspection and look for distortion (bent, pinched or stretched), damage (broken, chafed or cut), discoloration, overheating (burnt, melted or arcing), liquid contamination, loose electrical connection, or incorrect assembly of the items that follow:

Left Wing Group A AWM 284205

FQIC rack connector 3QT-A, pins 1D, 3C and 1E
92VU shelf receptacle 214VC and connector 214VC-A
receptacle 1521VC and connector 1521VC-A
receptacle 2973VC and connector 2973VC-A
receptacle 7107VC and connector 7107VC-A
pressure seal feedthrough 4015VP
fused connector 4041VC-A and receptacle 4041VC
connector 4039VC1-A, pins <Z, GG and AA
adjacent and related connecting wires

Left Wing Group B AWM 284211 and AWM 284213

FQIC rack connector 3QT-A, pins 4J, 7G and 5F
92VU shelf receptacle 210VC and connector 210VC-A
receptacle 1970VC and connector 1970VC-A
receptacle 7155VC and connector 7155VC-A
pressure seal feedthrough 4017VP
fused connector 4043VC-A and receptacle 4043VC
connector 4040VC1-A, pins <Z, GG and AA
adjacent and related connecting wires.

(b) Electrical Tests
Do a continuity test ESPM 2052210 and a test for a short circuit ESPM 2052220 of the wires that follow:

Left Wing Group A AWM 284205

FQIC rack connector 3QT-A, pin 1D to connector 4039VC1-A, pin <Z (dualcomp signal A)
FQIC rack connector 3QT-A, pin 3C to connector 4039VC1-A, pin GG (common drive return)
FQIC rack connector 3QT-A, pin 1E to connector 4039VC1-A, pin AA (common drive)

Left Wing Group B AWM 284211 and AWM 284213

FQIC rack connector 3QT-A, pin 4J to connector 4040VC1-A, pin <Z (dualcomp signal B)
FQIC rack connector 3QT-A, pin 7G to connector 4040VC1-A, pin GG (common drive return)
FQIC rack connector 3QT-A, pin 5F to connector 4040VC1-A, pin AA (common drive).

fused connectors 4041VC-A and 4043VC to their related receptacles AMM 28-42-43-400-008
tank wall connectors 4039VC1-A and 4040VC1-A to their related receptacles.

(e) Install the initial FQIC 3QT AMM 28-42-34-400-001.
(f) Do the test given in Para. 3.B.
(7) If the fault continues:
(a) Do a check for water contamination as given in the procedure 'Drain Water Content' AMM 12-32-28-281-001.
(b) Do a check (sample) for microbiological contamination AMM 12-32-28-281-003. If the results are MODERATE or HEAVY, do the applicable procedure or action AMM 28-11-00-600-003.

NOTE: Different microbiological contamination test kits are available. If no water is present in the drained sample, it is important to use a kit which can test contamination in the fuel phase. It is also important you make sure you use a kit which is correct for the timescale for the results availability.

(c) Get access to the left wing fuel-tank AMM 28-10-00-910-001 and AMM 28-10-00-910-002.
(d) If during the steps to get access to the fuel probe you find:
1 Microbiological contamination in the fuel-tank, do the steps that follow:
a Make a record of what you have found in the aircraft technical log.
b Remove all the microbiological contamination AMM 28-11-00-600-003.
2 Debris unwanted material (example, locking wire or an aircraft fastener), do the TSM procedure for Unwanted Material (Debris) In The Left (Right) Wing-Tank (Outboard of the RIb2) (Ref. TSM TASK 28-11-00-810-809).
(8) Do a check of the HARNESS-LEFT WING TANK A [57QT] AWM 284205 and replace, if necessary, AMM 28-42-43-000-005 and AMM 28-42-43-400-005.
(9) Do a check of the HARNESS-LEFT WING TANK B [63QT] AWM 284211 and replace, if necessary, AMM 28-42-43-000-005 and AMM 28-42-43-400-005.
(10) If the harnesses 57QT and 63QT are serviceable, replace the DUALCOMP-RIB 2-3, L WNG TK GROUP B [53QT] AMM 28-42-46-000-001 and AMM 28-42-46-400-001.

NOTE: If the left wing tank dualcomp 53QT is replaced, 1000kg (2200lb) of fuel must be put in the left wing tank before you can fully test the dualcomp.

Subtask 28-42-00-810-078-B ** ON A/C NOT FOR ALL

A. Procedure
(1) Transfer the fuel from the applicable wing tank AMM 28-25-00-869-001.
(2) Drain the residual water completely from the tank.
(3) Refuel the applicable wing tank with clean fuel AMM 12-11-28-650-003.
(4) Temporarily replace the FQIC 3QT with a serviceable item AMM 28-42-34-000-001 and AMM 28-42-34-400-001.

NOTE: The step (4) has been included because it is important to make sure that the FQIC is serviceable before you start more steps.

(5) If the message L DUALCOMP 53QT or L DUALCOMP 53QT/WRG:

Is not shown (and the related input parameter values show correct), complete the installation of the FQIC [3QT] AMM 28-42-34-000-001 and AMM 28-42-34-400-001
Is shown (and the related input parameter values stay incorrect), do step (6).

(6) Remove the temporary installed serviceable FQIC 3QT AMM 28-42-34-000-001 and return it to stores.
(7) Install the initial FQIC 3QT AMM 28-42-34-400-001.
(8) Get access to the fused connector 4043VC-A AMM 28-42-43-000-008.
(9) Remove the fused connector 4043VC-A.

NOTE: Each capacitive fuel probe is supplied with an alternating current drive from the FQIC.
The fuel probes in a tank group (harness) share the drive and drive return (two aircraft wires) between the FQIC rack connector and the fused connector 4043VC-A.
The fused connector is adjacent to and below its related tank wall connector.
In the fused connector:

The drive wire divides to supply each of its related fuel probes, in parallel
The drive return wire also divides to connect to each of its related fuel probes, in parallel through a fuse.
All of the discrete drive and drive return wires then go to the tank wall connectors 4040VC1-A.

(10) Use a MULTIMETER - STANDARD to do a check for continuity, of the related in line fuse ASM 284205 between the pins K and L.
(11) If the continuity test shows:
(a) The fuse has continuity (serviceable), install the serviceable fused connector and continue with step (12).
(b) The fuse is open circuit (first time unserviceable):
1 Replace the fused connector 4043VC-A with a serviceable item.
2 Do the test given in Para. 3.B.
(c) The fuse is open circuit (second time unserviceable):
1 Continue with step (12), only replace the fused connector 4043VC-A when the cause of the short corcuit has been identified and corrected.
(12) Get access to the fused connector 4041VC-A AMM 28-42-43-000-008.
(13) Remove the fused connector 4041VC-A.

NOTE: Each capacitive fuel probe is supplied with an alternating current drive from the FQIC.
The fuel probes in a tank group (harness) share the drive and drive return (two aircraft wires) between the FQIC rack connector and the fused connector 4041VC-A.
The fused connector is adjacent to and below its related tank wall connector.
In the fused connector:

The drive wire divides to supply each of its related fuel probes, in parallel
The drive return wire also divides to connect to each of its related fuel probes, in parallel through a fuse.
All of the discrete drive and drive return wires then go to the tank wall connectors 4039VC1-A.

(14) Use a MULTIMETER - STANDARD to do a check for continuity, of the related in line fuse ASM 284205 between the pins K and L.
(15) If the continuity test shows:
(a) The fuse has continuity (serviceable), install the serviceable fused connector and continue with step (12).
(b) The fuse is open circuit (first time unserviceable):
1 Replace the fused connector 4041VC-A with a serviceable item.
2 Do the test given in Para. 3.B.
(c) The fuse is open circuit (second time unserviceable):
1 Continue with step (12), only replace the fused connector 4041VC-A when the cause of the short corcuit has been identified and corrected.
(16) Get access to the tank wall connectors 4039VC1-A and 4040VC1-A and the fused connectors 4041VC-A and 4043VC-A AMM 28-42-43-000-008.
(a) Disconnect the:

Tank wall connectors 4039VC1-A and 4040VC1-A
Fused connectors 4041VC-A and 4043VC-A.

(17) Remove the FQIC 3QT AMM 28-42-34-000-001.
(18) Do a visual inspection and electrical tests of the aircraft wiring AWM 284205 AWM 284211 between the FQIC rack connector 3QT-AA and the tank wall connectors 4039VC1-A and 4040VC1-A as follows:
(a) Visual Inspection
Make sure that good lighting is available.
Do a visual inspection and look for distortion (bent, pinched or stretched), damage (broken, chafed or cut), discoloration, overheating (burnt, melted or arcing), liquid contamination, loose electrical connection, or incorrect assembly of the items that follow:

FQIC rack connector 3QT-AA, pins 1K, 3H, 2G, 3A, 7A and 4D
92VU shelf receptacles 210VC and 214VC and connectors 210VC-A and 214VC-A
Receptacles 1521VC and 1970VC and connectors 1521VC-A and 1970VC-A
Receptacle 2973VC and connector 2973VC-A
Receptacle 7107VC and 7155VC and connectors 7107VC-A and 7155VC-A
Pressure seal feedthroughs 4015VP and 4017VP
Fused connectors 4041VC-A and 4043VC-A and receptacles 4039VC1 and 4040VC1
Connector 4039VC1-A, pins <Z, GG and AA
Connector 4040VC1-A, pins <Z, GG and AA
Adjacent and related connecting wires.

(b) Electrical Tests
Do a continuity test ESPM 2052210 and a test for a short circuit ESPM 2052220 of the wires that follow AWM 284205, AWM 284211 and AWM 284213:

FQIC rack connector 3QT-AA, pin 1K to connector 4039VC1-A, pin <Z (dualcomp signal A)
FQIC rack connector 3QT-AA, pin 3H to connector 4039VC1-A, pin GG (common drive return)
FQIC rack connector 3QT-AA, pin 2G to connector 4039VC1-A, pin AA (common drive)
FQIC rack connector 3QT-AA, pin 3A to connector 4040VC1-A, pin <Z (dualcomp signal B)
FQIC rack connector 3QT-AA, pin 7A to connector 4040VC1-A, pin GG (common drive return)
FQIC rack connector 3QT-AA, pin 4D to connector 4040VC1-A, pin AA (common drive).

Fused connector 4041VC-A to the receptacle 4041VC AMM 28-42-43-400-008 and 4043VC-A to the receptacle 4043VC.
Tank wall connector 4039VC1-A to the receptacle 4039VC1
Tank wall connector 4040VC1-A to the receptacle 4040VC1.

(e) Install the FQIC 3QT AMM 28-42-34-400-001.
(f) Do the test given in Para. 3.B.
(19) If the fault continues:
(a) Do a check for water contamination as given in the procedure 'Drain Water Content' AMM 12-32-28-281-001.
(b) Do a check (sample) for microbiological contamination AMM 12-32-28-281-003. If the results are MODERATE or HEAVY, do the applicable procedure or action AMM 28-11-00-600-003.

(c) Get access to the applicable fuel tank AMM 28-10-00-910-001 and AMM 28-10-00-910-002.
(d) If during the steps to get access to the fuel probe you find:
1 Microbiological contamination in the fuel-tank do the steps that follow:
a Make a record of what you have found in the aircraft technical log.
b Remove all the microbiological contamination AMM 28-11-00-600-003.
2 Debris unwanted material (example, locking wire or an aircraft fastener), do the TSM procedure for Unwanted Material (Debris) In The Left (Right) Wing-Tank (Outboard of the RIb2) (Ref. TSM TASK 28-11-00-810-809).
(20) Do a check of the HARNESS-CHAN A, L WING TK INR [13QT1] AWM 284205 and replace, if necessary, AMM 28-42-43-000-006 and AMM 28-42-43-400-006.
(21) Do a check of the HARNESS-CHAN B, L WING TK INR [14QT1] AWM 284211 and replace, if necessary, AMM 28-42-43-000-007 and AMM 28-42-43-400-007.
(22) If the fault continues, replace the DUALCOMP-RIB 2-3, L WNG TK GROUP B [53QT] AMM 28-42-46-000-001 and AMM 28-42-46-400-001.

NOTE: If the left wing DUALCOMP 53QT is replaced, 1500kg (3300lb) of fuel must be put in the left wing inner cell before you can fully test the dualcomp.

5. Close-up
Subtask 28-42-00-942-078-A ** ON A/C NOT FOR ALL

A. Close-up and Removal of Equipment
(1) Do the EIS Stop Procedure AMM 31-60-00-860-002.
(2) If necessary, de-energize the aircraft electrical circuits AMM 24-41-00-862-002.
(3) Make sure that the access panel 574BB (674BB) opened during this trouble-shooting procedure is closed.
(4) Make sure that the work area is clean, clear of tool(s) and other items.
(5) Remove the ground support and maintenance equipment, the special and standard tools and all other items.

[Rev.8 from Aug 2018] 2026.04.04 04:29:03 UTC