Message Name:

NO L-HF-1 BUS OUTPUT

Message Code:

B3-006829

Associated CAS:

None

L-HF-1 bus data absent at L-RIU.

• Left HF Transceiver (HF 1) (A61)
• Left Radio Interface Unit (RIU 1) (A17)
• Left HF Remote-Control Circuit Breaker (RCCB) Contactor (K109)
• Left HF Current Thermal Sensor (RT3)
• HF 1 DC Circuit Breaker (CB1-B3)
• Left Cockpit Circuit Breaker Panel (CCBP 1)
• Left DC Power Center (L DCPC) (A35)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Reset HF 1 Circuit Breaker CB1-B3, RIU 1B/AURAL Circuit Breaker CB1-B4 and RIU 1A Circuit Breaker CB1-B5. Is the fault message still present?

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

2. Swap Left HF Transceiver (A61) with right HF Transceiver (A62). Is the fault message still present?

   1. If YES, continue with next step.
   2. If NO, replace defective HF Transceiver.

3. Swap Left RIU (A17) with right RIU (A18). Is the fault message still present?

1. If YES, continue with next step.
2. If NO, replace defective HF Transceiver.

4. Swap left HF RCCB Contactor (K109) located in the L DCPC (A35) with right HF RCCB Contactor (K108) located in the R DCPC (A36). Is the fault message still present?

   1. If YES, continue with next step.
   2. If NO, replace the defective RCCB Contactor.

5. Swap left HF Current Thermal Sensor (RT3) located in the L DCPC (A35) with right HF Current Thermal Sensor (RT4) located in the R DCPC (A36). Is the fault message still present?

   1. If YES, continue with next step.
   2. If NO, replace the defective Current Thermal Sensor.

6. Do wiring check between the left HF Transceiver (A61) and left RIU (A17) for the following wires:

   From	To	Result
   Conn. A61P1 - m	Conn. A17P1 - 61
   Conn. A61P1 - AA	Conn. A17P1 - 62

   1. If the check is satisfactory, continue with next step.
   2. If the check is not satisfactory, replace defective wiring.

7. Check presence of the ground at the left HF Transceiver (A61).

   Measurement at	Expected Result	Result
   Conn. A61P4 - E	Aircraft Ground (pwr gnd)
   Conn. A61P4 - F	Aircraft Ground (pwr gnd)
   Conn. A61P4 - G	Aircraft Ground (pwr gnd)
   Conn. A61P4 - H	Aircraft Ground (pwr gnd)
   Conn. A61P4 - K	Aircraft Ground (pwr gnd)
   Conn. A61P1 - e	Aircraft Ground (chassis gnd)
   Conn. A61P1 - V	Aircraft Ground (chassis gnd)
   Conn. A61P1 - FF	Aircraft Ground (chassis gnd)
   Conn. A61P1 - HH	Aircraft Ground (chassis gnd)

   1. If the check is satisfactory, continue with step next step.
   2. If the check is not satisfactory, repair the defective wiring.

8. Check presence of the 28VDC at the left HF Transceiver (A61).

   Measurement at	Expected Result	Result
   Conn. A61P4 - A	28VDC (pwr)
   Conn. A61P4 - B	28VDC (pwr)
   Conn. A61P4 - C	28VDC (pwr)
   Conn. A61P4 - D	28VDC (pwr)
   Conn. A61P4 - J	28VDC (pwr)

   1. If the check is satisfactory, do close out.
   2. If the check is not satisfactory, continue with next step.

9. Do wiring check between the left HF Transceiver (A61) and left DCPC (A35) for the following wires:

   From	To	Result
   Conn. A61P4 - A	Conn. A35P4 - 25
   Conn. A61P4 - B	Conn. A35P4 - 25
   Conn. A61P4 - C	Conn. A35P4 - 25
   Conn. A61P4 - D	Conn. A35P4 - 25
   Conn. A61P4 - J	Conn. A35P4 - 25

1. If the check is satisfactory, continue with next step.
2. If the check is not satisfactory, replace defective wiring.

10. Check proper operation of the HF 1 control input at the L DCPC (A35).

    HF 1 CB1-B3 Status	Measurement at	Expected result	Result
    Closed	Conn. A35P4 - 6	Ground
    Open	Conn. A35P4 - 6	Infinite Resistance

    1. If the check is satisfactory, continue with step 13.
    2. If the check is not satisfactory, continue with next step.

11. Do wiring check between the left Cockpit Circuit Breaker Panel (CCBP1) and left DCPC (A35) for the following wires:

    From	To	Result
    Conn. CBP1J3 - 36	Conn. A35P4 - 6
    Conn. CBP1J3 - 13	Aircraft Ground

    1. If the check is satisfactory, continue with next step.
    2. If the check is not satisfactory, replace defective wiring.

12. Replace HF 1 Circuit Breaker CB1-B3. Is the fault message is still present?

1. If NO, do close out.
2. If YES, replace defective left Cockpit Circuit Breaker Panel (CCBP1).

13. Replace Left DCPC (A35).
14. Do close out.