SPLRS/STAB BIT
(Advisory)

It warns the crew of the occurrence of a failure relative to the EFCS system and shows only on the ground.

• Multi Function Spoiler and Ground Spoiler Proximity Sensor Switch
• Throttles RVDTs
• FCM Busses
• Wheel Speed Sensors
• Roll Input Control Module RVDT
• HSTA Position RVDT
• Flight Spoiler Control Lever RVDT
• Availability of Pitch Feel Control in one FCM
• Availability of Rudder Travel Limitation Control in one FCM
• Availability of Ground Spoiler Control in one FCM
• Availability of HST Control in one FCM except for PITCH TRIM OFF & MASTER DISCONNECT Conditions (cockpit switches effects)
• MDU BIT INVALID Condition (MDU status)
• Flight Control Computer (FCU)
• Brake Control Unit (BCU) (A71)
• Brake Control Valve (BCV)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Full Throttle Blog/Forum Articles/Infoservice/Newsletter:

• Forum Newsletter Volume 16 issue 08 2019-04-17 - SPLRS/STAB BIT - Reducing the No Fault rate of the Flight Control Unit (FCU)

Flight Operation Notifications Manual (FONM): None

NOTES:

• To support a NFF technical investigation please fill out this Questionnaire and send it to your FSR if you are replacing an Flight Control Unit (FCU).
• The Flight Control System Reset procedure may be performed in an attempt to clear the fault message.

Message Code:

1. Using the PMAT, access the CAIMS Active Faults/Stored Faults
2. Select displayed CAIMS message below:
   Select an Item27653191SX - PITCH FEEL ACTR #1 POT/WRG FAULT27653192SX - PITCH FEEL ACTR #2 POT/WRG FAULT27654261SX - FLT CONT 2B FAULT [FCU 1]27654262SX - FLT CONT 1B FAULT [FCU 2]27654271SX - FLT CONT 2A FAULT [FCU 1]27654272SX - FLT CONT 1A FAULT [FCU 2]27654281SX - FLT CONT 1B FAULT [FCU 1]27654282SX - FLT CONT 2B FAULT [FCU 2]27654291SX - FLT CONT 1A FAULT [FCU 1]27654292SX - FLT CONT 2A FAULT [FCU 2]27655200SX - HORIZ STAB ACTUATOR / WRG FAULT27655221SX - HORIZ STAB ACTR MOTOR #1/WRG FAULT27655222SX - HORIZ STAB ACTR MOTOR #2/WRG FAULT27655241SX - RUD LIMITER POS XDCR #1/WRG FAULT27655242SX - RUD LIMITER POS XDCR #2/WRG FAULT27655270SX - PLT ROLL CTL IN MDL XDCR/WRG FAULT27655280SX - CPLT ROLL CTL IN MDL XDCR/WRG FAULT27656201SX - LH OUTBD GS RET SNSR / WRG FAULT27656202SX - LH INBD GS RET SNSR / WRG FAULT27656211SX - RH OUTBD GS RET SNSR / WRG FAULT27656212SX - RH INBD GS RET SNSR / WRG FAULT27656261SX - RH MFS #4 RET SNSR/WRG FAULT27656262SX - RH MFS #2 RET SNSR/WRG FAULT27656271SX - RH MFS #1 RET SNSR/WRG FAULT27656272SX - RH MFS #3 RET SNSR/WRG FAULT27656281SX - LH MFS #4 RET SNSR/WRG FAULT27656282SX - LH MFS #2 RET SNSR/WRG FAULT27656291SX - LH MFS #1 RET SNSR/WRG FAULT27656292SX - LH MFS #3 RET SNSR/WRG FAULT27657162SX - FCU #2/ INTERNAL BUS FAULT [FCM A]27657240SX - CPLT MASTER DISCONNECT SW/WRG FAULT27657250SX - PLT MASTER DISCONNECT SW/WRG FAULT27657280SX - H STAB PLT TRIM SWITCH/WRG FAULT27657290SX - H STAB CPLT TRIM SWITCH/WRG FAULT27660241SX - FCU #2/ BUS FAULT [FCU2/FCM A]27660242SX - FCU #1/ BUS FAULT [FCU1/FCM A]27660251SX - FCU #2/ BUS FAULT [FCU2/FCM B]27660252SX - FCU #1/ BUS FAULT [FCU1/FCM B]27660262SX - FCU #2/ INTERNAL BUS FAULT [FCM B]27661151SX - PITCH FEEL ACTR #1/WIRING FAULT27661152SX - PITCH FEEL ACTR #2/WIRING FAULT27661221SX - SPOILER CTRL LEVER [CH1]/WRG FAULT27661222SX - SPOILER CTRL LEVER [CH2]/WRG FAULT27661241SX - THROTTLE QUAD [CH A]/WRG FAULT27661242SX - THROTTLE QUAD [CH B]/WRG FAULT27661261SX - H STAB MOT DR UNIT [CH1]/WRG FAULT27661262SX - H STAB MOT DR UNIT [CH2]/WRG FAULT27661271SX - HOR STAB POS XDCR #1/WRG FAULT27661272SX - HOR STAB POS XDCR #2/WRG FAULT27661281SX - RUD LIMITER ACTR #2/ WRG FAULT27661282SX - RUD LIMITER ACTR #2/ WRG FAULT27661291SX - BRAKE CTRL UNIT [CH A]/ WRG FAULT27661292SX - BRAKE CTRL UNIT [CH B]/ WRG FAULT27662211SX - RUD LIMITER ACTR#2 POT/WRG FAULT27662212SX - RUD LIMITER ACTR#1 POT/WRG FAULT27662221SX - H STAB MOTOR #1/ACT/WRG FAULT27662222SX - H STAB MOTOR #2/ACT/WRG FAULT27662241SX - HST MDU[CH1]/ACTUATOR FAULT27662242SX - HST MDU[CH2]/ACTUATOR FAULT27662281SX - HST MDU[CH1]/MOTOR #1/ACT/WRG FAULT27662282SX - HST MDU[CH2]/MOTOR #2/ACT/WRG FAULT27662331SX - RTL DISCNCT/RVDT#1 MISRIG FAULT27662332SX - RTL DISCNCT/RVDT#2 MISRIG FAULT
3. When the Spoiler Stab bit appears on landing, perform the next steps to isolate a defective Brake Control Valve.
   A defective Brake Control Valve can be identified by looking at all 4 brake pressures from the CAIMS, the goal is to identify which position show a different pressure from the other 3. The following steps are methods to achieve this verification:

   1. Access CAIMS System Diag Menu.
   2. Select ATA 32, Landing Gear, Brake Control Unit.
   3. Select: System Data Pages.
   4. Navigate to Brake Control System Data Page 2

4. Pressurize the No. 2 & No. 3 hydraulic systems.

   • Check the Brake Pressures. (Pressure should be less than 100 psi (Nominal 80 ±5 psi)
   • Push the Brakes make sure all the Brake Pressures moves at the same rate. (Record a video of the CAIMS page while you are doing this and send it to the CRC)
   • Apply the brakes at least 10 times. In the CAIMS, monitor the brake pressure at each brake position
   • With Aircraft on Jack, spin each wheel and check if one position show a higher resistance.

5. Release No. 2 & No. 3 Hydraulic pressure

   1. With Aircraft on Jack, spin each wheel and see if there is a dragging brake. 

6. Do close out

NOTE: If one of the brake pressures holds longer or stays above 100 psi (It could happen only one time), then brake control valve associated to the brake position is defective and will need replacement.