Fuel Quantity Probe 51QT, Center Tank

TASK 28-42-00-810-827-A
Fuel Quantity Probe 51QT, Center 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
water contamination
microbiological contamination
unwanted material
HARNESS-CHAN B, CTR TK [18QT]
PROBE-FQI NO. 5, CENTER TANK [51QT]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 28-11-00-810-810-A	Fuel - Unwanted Material (Debris) In The Center-Tank Fuel Installation
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 12-32-28-281-001	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 28-42-00-00-
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 284209
AMM 28-42-15-000-004	Removal of the Center (Transfer) Tank Fuel-Quantity Probes
AMM 28-42-15-400-004	Installation of the Center (Transfer) Tank Fuel-Quantity Probe
AWM 284216
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 28-42-44-000-002	Removal of the Center Tank Harness
AMM 28-42-44-400-002	Installation of the Center Tank Harness
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
AMM 32-12-00-010-001	Open the Main Gear Doors for Access
AMM 32-12-00-410-001	Close the Main Gear Doors after Access
TSM TASK 28-42-00-03	QUANTITY INDICATING - TASK SUPPORTING DATA

3. Fault Confirmation
Subtask 28-42-00-865-073-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 28-42-00-710-076-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.

(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:
(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 C QTY PROBE 51QT or C QTY PROBE 51QT/WRG) is shown and the values given on the I/P PARAMETER page 1 are correct (but related value on page 2 is shown with a - (dash) or out of range), do Para. 4.A.
if the message C QTY PROBE 51QT or C QTY PROBE 51QT/WRG is not shown and the values shown on the I/P PARAMETER pages are correct, no trouble shooting 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.

You can get the normal range of fuel-probe capacitance values (at dry and full) 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 284209.

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).

4. Fault Isolation
Subtask 28-42-00-810-076-A ** ON A/C NOT FOR ALL

A. Procedure
(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 3QT is serviceable before you start more steps.

(2) If the message C QTY PROBE 51QT or C QTY PROBE 51QT/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 temporarily installed FQIC 3QT and return it to stores AMM 28-42-34-000-001.
(4) Get access to the tank wall connector 7512VC in the right MLG bay AMM 32-12-00-010-001.
(5) Do a visual inspection and electrical tests of the aircraft wiring AWM 284216 between the FQIC rack connector 3QT-A and the tank wall connector 7512VC-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-A, pins 6H, 7J and 7H
receptacle 210VC and connector 210VC-A
receptacle 1970VC and connector 1970VC-A
terminal block 7522VT and all of its connections
receptacle 7570VC and connector 7570VC-A
pressure seal feedthrough 7510VP
receptacle 7512VC-A, pins U, D and C
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 284216:

FQIC rack connector 3QT-A, pin 6H to connector 7512VC-A, pin U (signal)
FQIC rack connector 3QT-A, pin 7J to connector 7512VC-A, pin D (common drive return)
FQIC rack connector 3QT-A, pin 7H to connector 7512VC-A, pin C (common drive).

(c) Repair all the unserviceable wiring and connectors ESPM 2053210.
(d) Connect the connector 7512VC-A to the tank wall receptacle 7512VC.
(e) Install the initial FQIC 3QT AMM 28-42-34-400-001.
(f) Do the test given in Para. 3.B.
(6) 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 center 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 Center-Tank Fuel Installation (Ref. TSM TASK 28-11-00-810-810).
(7) Do a check of the HARNESS-CHAN B, CTR TK [18QT] AWM 284216 and replace, if necessary, AMM 28-42-44-000-002 and AMM 28-42-44-400-002.
(8) If the harness 18QT is serviceable, replace the PROBE-FQI NO. 5, CENTER TANK [51QT] AMM 28-42-15-000-004 and AMM 28-42-15-400-004.

Subtask 28-42-00-810-076-B ** ON A/C NOT FOR ALL

A. Procedure
(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 3QT is serviceable before you start more steps.

(2) If the message C QTY PROBE 51QT or C QTY PROBE 51QT/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 to the tank wall connector 7512VC in the right MLG bay AMM 32-12-00-010-001.
(5) Do a visual inspection and electrical tests of the aircraft wiring AWM 284216 between the FQIC rack connector 3QT-AA and the tank wall connector 7512VC-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 6B, 7C and 7B.
Receptacle 210VC and connector 210VC-A
Receptacle 1970VC and connector 1970VC-A
Terminal block 7522VT and all of its connections
Receptacle 7634VC and connector 7634VC-A
Pressure seal feedthrough 7510VP
Receptacle 7512VC-A, pins U, D and C
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 284216:

FQIC rack connector 3QT-AA, pin 6B to connector 7512VC-A, pin U (probe 5 signal)
FQIC rack connector 3QT-AA, pin 7C to connector 7512VC-A, pin D (common drive return)
FQIC rack connector 3QT-AA, pin 7B to connector 7512VC-A, pin C (common drive).

The connector 7512VC-A to the fused adaptor
The fused adaptor to the tank wall receptacle 7512VC.

(e) Install the initial FQIC 3QT AMM 28-42-34-400-001.
(f) Do the test given in Para. 3.B.
(6) 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.

5. Close-up
Subtask 28-42-00-942-077-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 applicable, close the MLG doors AMM 32-12-00-410-001.
(3) If necessary, de-energize the aircraft electrical circuits AMM 24-41-00-862-002.
(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 04:29:02 UTC