TC reported front DT stuck brake. Operated STBS. ~~~~~ To further check

L3 569/570 3569 Stuck Brake (L3)

1. Fault confirmed/Fault cannot duplicate
Fault not duplicated in depot.

2. What was found from ER/Fault record?
-From ER, found BRER dropped during fault timing.
-#3569 brakes were stuck at 2.8 bar from 1908hr, all others cars were close to 0 bar
-FC 308, 330, 331, 312 BCU release fault were registered.

3. Troubleshooting details
These are 4 identified causal factors based on FTA:

1. Faulty ACU
Likely
- No abnormalities found on ACU during depot brake cyclic checks. Brakes were able to release and apply as
required. Postulate ACU solenoid valves causing intermittent release fault based on ER and FC.

2. Electrical Stuck Brake
Unlikely
- BRER, ABRR1/2, PBPR, ELB2R, COR1/2 relay condition satis. Function check able to energies as required.

3. Faulty BCU
Unlikely
- During function cx, #3569 BCP was able to show signs of regulation when brakes were commanded, suggesting that BCU was able to monitor and regulate the BCP.

4. Defective connection from BCU to ACU
Unlikely
- Checked wiring-ok. No signs of looseness.

4. Rectification details
- Replaced ACU as ER and FC points towards it as the most likely cause of fault. Brakes were able to release and coast at 0 bar.
- Preventively replaced B13 check v/v and control pressure transmitter
- Brake cyclic test carried out and brake pressure all within criteria.
- Side finding: Found BCP1: 0.08bar and BCP2: 0.05bar at coast respectively. Replaced pressure transmitter for BCP 1 and 2
- Side finding: Found 1 test point RHS of brake frame heavy air leak. Replaced-ok
- STBS resealed

BC1 Pressure Transmitter:
S/N:  
Notif to csc: 2519564

BC2 Pressure Transmitter:
S/N:  
Notif to csc: 2519565

3569 ACU (DT)
Old S/N: 1241-044
New S/N: 1107-038
Notif to CSC: 2519740

3569 no. 1 Pressure Transmitter
S/N:  
Notif to CSC: 2519741

Done by: Zulqarnain, Asruddin, Saini, Haslan
31/08/23