RUDDER LIMITER FAULT
(Advisory)

Minor failure resulting from the loss of redundancy within the rudder limiter system.

• One ADC Failed
• OR one position monitor failed (DCU RTL position monitor or RTL position monitor)
• OR the pre-flight test has not been run for 10 flights (counter in the HST ECU)
• STALL RUD LIM TEST needs to be performed

• Junction Box 2 (JB2)
• Rudder Travel Limiter Rotary Variable-Differential Transducer (RTL RVDT) (MPE20)
• Rudder Travel Limiter Actuator (RTLA) (MPE79)
• Horizontal Stab Trim Electronic Control Unit (HST ECU) (A130)
• Air Data Computer (ADC) (A1)
• Air Data Computer (ADC) (A2)
• Associated Wiring

Advisory Wire/Service Bulletin:

• AW300-27-34-0010 - Integrated Standby Instrument (ISI) Airspeed Indication Fluctuation & Potential STALL PROTECT FAIL and/or RUDDER LIMITER FAULT Messages

Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

NOTES:

• ATA 27-00-00 FLIGHT CONTROLS TROUBLESHOOTING TIPS
• If the message is present at power up, make sure to wait for the standby instrument to power up and the message to clear afterwards.
• The HST ECU has an internal counter. Every 10 flights the RTL pre-flight test must be run. The test can be initiated from the systems test rotary switch on the center pedestal.

Fault Clearing (Rain, wet weather)

If the aircraft is outside in the rain and an ISI/ADC MACH DISAGREE (B3-007965) message is posted one quick fix would be to turn on the pitot heat.

• Do not exceed 5 minutes. What this does is dry up any moisture inside the pitot probe that is obstructing the dynamic pressure entry point.
• Or taxi the aircraft at a speed that would induce enough pressure to blow out any moisture trapped in the line.
• If CAS messages:

  • RUDDER LIMITER FAULT (Advisory),
  • PRI STAB TRIM FAIL (Caution) and
  • YAW DAMPER FAIL (Caution)

    • are displayed at the same time and the TRIM PRI STAB (CBP1-LCBP) circuit breaker (CB) is tripped, access the Rudder Travel Limiter Actuator (RTLA) and disconnect it. Set the CB back to IN and apply power to the aircraft. If the CB does not trip, replace the RTLA.

1. Access FCC diagnostics, located the Indicated Air Speed (IASSBY) value.
   NOTE: a difference of 20kts or more between ISI and the MADC could cause of the Rudder Limiter Fault. (ref AW300-27-34-0010)
2. Make sure to inspect the Pitot Static system drains. If water is present or you suspect the aircraft of having been in rain conditions, purge the Pitot Static system. Is the fault still present?

   1. If YES, continue with next step.
   2. If NO, do close out.

3. Reset the following circuit breakers with L Hyd, R Hyd and AUX Hyd pressurized.

   PRI STAB TRIM/RUD LIM	CB1-B15
   SEC STAB TRIM/RUD LIM	CB2-B13

   NOTE: Keep circuit breakers pulled for 10 seconds.

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

4. Check the current faults and fault history for problems related to the Rudder Travel Limiter system.
   Select an MDC Fault Code/Message:B3-006875 - RTLA POSITION FAULT [HORIZ TRIM ECU]B3-006876 - RTLA FAULT [HORIZ TRIM ECU]B3-006877 - RTL DISCONNECT [HORIZ TRIM ECU]B3-006878 - RTL SECONDARY [HORIZ TRIM ECU]B3-007124 - RTL RVDT FAULT [RTL RVDT]
   

   1. If fault is found, troubleshoot by selecting an MDC fault.
   2. If no fault is found, continue with next step.

5. Do Electrical Rigging of the Rudder Travel-Limiter Actuator

   1. If rigging passes, do close out.
   2. If rigging fails, continue with next step.

6. Do Detailed Inspection of the Rudder Travel Limiter. Replace/repair as required.
7. Do wiring check between RTLA connectors, HST ECU connectors, Junction Box 2, RTL RVDT and DCU. Repair/replace as required.

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

8. Check RTL RVDT internal wiring for continuity, short-circuit and insulation.

   1. If RTL RDVT internal wiring is confirmed good, go to step 10.
   2. If RTL RVDT internal wiring is not good, continue with next step.

9. Replace RTL RVDT.

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

10. Replace RTLA.

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

11. Replace HST ECU.
12. Do close out.