SFCC - Slat PCU Valveblock Fault

TASK 27-81-00-810-801-A
SFCC - Slat PCU Valveblock Fault

1. Possible Causes

solenoid valve
SLAT/FLAP CONTR.COMP. [21CV]
SLAT/FLAP CONTR.COMP. [22CV]
valve block filters
VALVE BLOCK SLAT 1 [25CV]
VALVE BLOCK SLAT 2 [26CV]
aircraft wiring

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

REFERENCE	QTY	DESIGNATION
No specific	1	MEGOHMMETER 100 MOHMS - MEASURING VOLTAGE 45 VDC
No specific	1	MULTIMETER - STANDARD

B. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 27-81-00-810-837-A	Slats - SFCC 1 (2) Gives PCU Valveblock 25CV (26CV) Valve Sensor Message
AMM 27-51-34-000-001	Removal of the SFCC
AMM 27-51-34-400-001	Installation of the SFCC
AMM 27-80-00-866-004	Extending the Slats on the Ground
AMM 27-80-00-866-005	Retracting the Slats on the Ground
ASM 278102
ASM 278103
AMM 27-84-53-000-001	Removal of the Valve Blocks of the Power Control Unit (Slat)
AMM 27-84-53-000-002	Removal of the Solenoid Valves of the Power Control Unit (Slat)
AMM 27-84-53-000-003	Removal of the Filters of the Valve Blocks
AMM 27-84-53-400-001	Installation of the Valve Blocks of the Power Control Unit (Slat)
AMM 27-84-53-400-002	Installation of the Solenoid Valves of the Power Control Unit (Slat)
AMM 27-84-53-400-003	Installation of the Filters of the Valve Blocks
AMM 31-32-00-860-006	Procedure to Get Access to the SYSTEM REPORT/TEST F/CTL Page

3. Fault Confirmation
Subtask 27-81-00-710-050-A

A. Test
(1) Make sure that the Post Flight Report does not show any hydraulic system faults.
(2) Move the slats AMM 27-80-00-866-004 and AMM 27-80-00-866-005.
(a) Examine the SFCC, SLT ON GROUND FAULTS page for a PCU valve block message.
(3) If a valve block message is shown, or the A/C has had this fault before, do the fault isolation procedure.
(4) If the fault message SLT 1 (2) PCU VALVEBLOCK 25CV (26CV) VALVE SENSOR 27-84-53 is shown, do TSM Task (Ref. TSM TASK 27-81-00-810-837).

4. Fault Isolation
Subtask 27-81-00-810-050-A

A. Procedure

CAUTION: MAKE SURE THAT YOU DO NOT CAUSE A SHORT CIRCUIT IN THE WIRING TO THE SOLENOID VALVES. A SHORT CIRCUIT CAN CAUSE DAMAGE TO THE SFCC(S).

(1) Do a check of the PLR for SLT1 (2) PCU VALVEBLOCK 25CV (26CV) VALVE SENSOR 27-84-53 message. If this message is shown, do TSM Task (Ref. TSM TASK 27-81-00-810-837).

NOTE: This message is not a CFDS Normal Mode message and is only shown in SFCC reports.

(2) Do a check of the circuit resistance and the circuit isolation of the extend and retract solenoids on each slat system PCU valve block (25CV, 26CV) as follows:
(a) Get access to the electrical connector on each valve block AMM 27-84-53-000-001.
1 At the connector receptacle on each valve block, use a MULTIMETER - STANDARD to measure the resistance values of the extend and retract solenoids ASM 278102 or ASM 278103:

for the extend solenoid measure between pins H and J
for the retract solenoid, measure between pins T and U.

2 The resistance values must be as follows:

for solenoid valves with Part No. 667C0000-02, between 71 Ohms and 84 Ohms.
for solenoid valves with Part No. 903A0000-01, between 53 Ohms and 60 Ohms.
for solenoid valves with Part No. 1106A0000-01 or 1111A0000-01, between 53 Ohms and 60 Ohms.
for solenoid valves with Part No. 5751A0000-01, between 53 Ohms and 60 Ohms.

3 Use a MEGOHMMETER 100 MOHMS - MEASURING VOLTAGE 45 VDC or a 50VDC +5VDC/-5VDC Isolation Tester to do a check of the extend and retract solenoid circuit isolation:

for the extend solenoid connect the pins H and J together
for the retract solenoid connect the pins T and U together.

4 Connect one test lead of the Isolation Tester to the pins JH or TU and the other test lead to pin G ASM 278102 and ASM 278103:
5 Supply a test signal for 5 seconds and then read the resistance value shown:

the resistance value must be more than 100 Megohms.

(b) If the results of the solenoid valve tests:

are OK, do step (4)
are not OK, do the next step.

(3) Replace the applicable solenoid valve ,
AMM 27-84-53-000-002 and AMM 27-84-53-400-002.
(a) If the fault continues, do the next step.
(4) Interchange the SFCC1 and SFCC2 AMM 27-51-34-000-001 and AMM 27-51-34-400-001.
(a) Do the test in Para. 3.A.(2):

if the fault stays in the same system, do step (6)
if the fault moves to the other system, do the next step.

(5) Replace the SLAT/FLAP CONTR.COMP. [21CV] or the SLAT/FLAP CONTR.COMP. [22CV] in the unserviceable system,
AMM 27-51-34-000-001 and AMM 27-51-34-400-001.
(a) Do the test in Para. 3.A.(2):

if the fault continues, do the next step.

(6) Examine and clean/replace as necessary the valve block filters , AMM 27-84-53-000-003 and AMM 27-84-53-400-003.
(a) Do the test in Para. 3.A.(2). Operate the slats many times during the test, to bleed the air from the system:

if the fault continues, do the next step.

(7) Replace the applicable VALVE BLOCK SLAT 1 [25CV] or VALVE BLOCK SLAT 2 [26CV] , AMM 27-84-53-000-001 and AMM 27-84-53-400-001:

if the fault continues, do the next step.

(8) Do a check and repair as necessary, the aircraft wiring from the applicable SFCC ARINC tray interface to the valve block electrical connector ASM 278102 or ASM 278103.
(a) Do the test in Para. 3.A.(2).
(9) At the MCDU get access to the SFCC SYSTEM STATUS page and make sure that the message NO FAULTS is shown AMM 31-32-00-860-006.

NOTE: More data on the SYSTEM STATUS page can be found in Page Block 301.

5. Close-up
Subtask 27-81-00-942-050-A

A. Remove the ground support and maintenance equipment, the special and standard tools and all other items.

Subtask 27-81-00-860-050-A

B. Put the aircraft back to its initial configuration.

[Rev.8 from Aug 2018] 2026.04.04 04:39:16 UTC