Message Name:

L FTB FAULT

Message Code:

B3-276334

Associated CAS:

FLAPS FAIL
(Caution)

Left Flap Transmission Brake fault. Replace L FTB. After FTB is replaced, perform FTB test.

• Left Flap Transmission Brake (FTB) (A203)
• Flap Control Unit (FCU) (A124)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

NOTES: 

• In the MDC system parameters, an FPU PRESS XDCR SIGNAL showing 3740 PSI indicates the FCU has detected a malfunction in the system and does not send the excitation signal to the FPU pressure transducer.

1. Reset the following circuit breakers:

   FLAP R IND	CB2-B12
   FLAP L IND	CB1-B13
   FLAP CTRL	CB1-B14

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

2. Reset the FCU by pressing the FCU reset button (ref. AMM ATA 27-52-00).

   1. If reset is successful, perform an MDC Download (ref. AMM ATA 45-45-00).
   2. If system checks are good, do operational test of Flap Transmission Brake per AMM and do close out.
   3. If problem remain continue to next step.

3. Do a Flap Transmission Break Resistance Check as follows:

   1. Remove connectors from Left Flap Transmission Brake and Record Resistance of Solenoid Coils.
      NOTE: All are the same P/N and LRU replaceable.

      FTB Left Side	FCU 124AP1	Or FTB A203:	Typical Reading
      A203P1 Solenoid # 1	6J to 5J	Pins 1-2 =	(Normal ≈ 58Ω)
      A203P2 Solenoid # 2	6G to 5G	Pins 1-2 =	(Normal ≈ 58Ω)

   2. If reading is not as specified, replace L FTB per AMM. Do close out.
   3. If problem remains, continue to next step.

4. Do Flap Transmission Break Voltage Check as follows:

   Release the Flap Transmission Brake with the MDC as follows:
   FTB release procedure through MDC:

   PROCEDURE	APPLICABLE RESULT
   Push the A/ICE, ECS, and FUEL buttons at the same time to access the maintenance diagnostic computer (MDC).	MAINTENANCE MAIN MENU shows on the MDC.
   Use the joystick and ENTER button to select LRU RIGGING.	LRU INDEX ALL ATA CHAPTERS page shows on the MDC.
   Use the joystick and ENTER button to select FLAP CTRL UNIT.	The LRU OPERATIONS ATA 27-52 FLAP CTRL UNIT PAGE shows on the MDC.
   Use the joystick and ENTER button to select RIGGING.	The FLAPS RIGGING 1/2 page shows on the MDC.
   Use the joystick and ENTER button to select START MECHANICAL RIGGING.	The FLAP MECHANICAL RIGGING 2/2 page shows on the MDC.
   Use the joystick and ENTER button to select LH & RH FTB OPEN.	The FTB STATUS shows OPEN on the MDC.

   Record voltages at each connector. Check each with Normal and Alternate flaps. Should be approx 28 VDC.

   FTB A203 Left Side		Normal Flaps:	Alternate Flaps:
   A203P1 Solenoid # 1	Pin 1 to ground	0 VDC	28 VDC
   A203P2 Solenoid # 2	Pin 1 to ground	28 VDC	0 VDC

   1. If reading is not as specified, do wiring check from FCU to FTB. Repair as required.
   2. If problem remains, continue with next step.

5. Replace L FTB per AMM.
6. Do close out.