Loss of the VBV Feedback Signal - Engine 1 - Channel A
TASK 75-30-00-810-813-A
Loss of the VBV Feedback Signal - Engine 1 - Channel A
1. Possible Causes
A. Referenced Information
3. Fault Confirmation
Subtask 75-30-00-710-076-A ** ON A/C NOT FOR ALL
Subtask 75-30-00-810-063-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:37:07 UTC
Loss of the VBV Feedback Signal - Engine 1 - Channel A
1. Possible Causes
VBV sensor (RVDT) - ECU [4000KS]
- harness J11
- harness CJ11L
- harness HJ11
A. Referenced Information
| REFERENCE | DESIGNATION |
|---|---|
| AMM 73-21-50-000-001 | Removal of the CJ11L Harness |
| AMM 73-21-50-000-010 | Removal of the J11 Harness |
| AMM 73-21-50-000-025 | Removal of the CJ11L Harness |
| AMM 73-21-50-000-044 | Removal of the HJ11 Harness for SAC Engines |
| AMM 73-21-50-210-001 | Visual Inspection of the Wiring Harness |
| AMM 73-21-50-210-002 | Visual Inspection of the Wiring Harnesses |
| AMM 73-21-50-400-001 | Installation of the CJ11L Harness |
| AMM 73-21-50-400-010 | Installation of the J11 Harness |
| AMM 73-21-50-400-025 | Installation of the CJ11L Harness |
| AMM 73-21-50-400-044 | Installation of the HJ11 Harness for SAC Engines |
| AMM 73-21-60-000-001 | Removal of the Electronic Control Unit (ECU) |
| AMM 73-21-60-400-001 | Installation of the Electronic Control Unit (ECU) |
| AMM 73-29-00-710-040 | Operational Test of the FADEC on the ground (with Engine Motoring) |
| AMM 75-31-00-200-001 | Manual Operation Check of the Variable Bleed Valve Doors |
| AMM 75-31-00-200-002 | Manual Operation Check of the Variable Bleed Valve Doors |
| AMM 75-31-70-000-001 | Removal of the Variable Bleed Valve Position Sensor |
| AMM 75-31-70-000-002 | Removal of the Variable Bleed Valve position Sensor |
| AMM 75-31-70-400-001 | Installation of the Variable Bleed Valve Position Sensor |
| AMM 75-31-70-400-002 | Installation of the Variable Bleed Valve position Sensor |
Subtask 75-30-00-710-076-A ** ON A/C NOT FOR ALL
A. Do the operational test of the FADEC 1A on the ground (with engine non motoring) AMM 73-29-00-710-040.
4. Fault IsolationSubtask 75-30-00-810-063-A ** ON A/C NOT FOR ALL
A. The failure message is generated if the channel A signal is invalid, out of range, or both channels disagree.
(1) If the failure message VBV SENS, J11, ECU is not confirmed:
(a) No maintenance action is required.
(2) If the failure message VBV SENS, J11, ECU is not confirmed but is repetitive:
Subtask 75-30-00-810-063-B ** ON A/C NOT FOR ALL (1) If the failure message VBV SENS, J11, ECU is not confirmed:
(a) No maintenance action is required.
(2) If the failure message VBV SENS, J11, ECU is not confirmed but is repetitive:
- disconnect the CJ11L harness from the VBV sensor (VBV-A connector) located in the left core compartment and visually examine the receptacle and the harness for damaged pins and contamination AMM 73-21-50-210-001.
- repair or replace as required.
- replace the
VBV sensor (RVDT) AMM 75-31-70-000-001 and AMM 75-31-70-400-001.
NOTE: After new VBV sensor is installed, a rigging of the VBV system is required AMM 75-31-00-200-001.
(c) If the fault continues during the subsequent flights: - disconnect the J11 harness from the ECU (4000KS) and visually examine the receptacle and the connector for damaged pins and contamination AMM 73-21-50-210-001.
- repair or replace as required.
- replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.
- replace the harness J11 (ECU to the 6 o'clock junction box) AMM 73-21-50-000-010 and AMM 73-21-50-400-010.
- replace the harness CJ11L (located in the left core compartment) AMM 73-21-50-000-001 and AMM 73-21-50-400-001.
- disconnect the CJ11L harness from the VBV sensor (VBV-A connector) located in the left core compartment and visually examine the CJ11L harness connector and the VBV sensor (RVDT) receptacle for damaged pins and contamination AMM 73-21-50-210-001.
- repair or replace as required.
- do an electrical resistance test through the VBV sensor between:
. pins 2 and 3 (80 to 110 ohms)
. pins 4 and 5 (80 to 120 ohms)
. pins 6 and 7 (85 to 120 ohms)
. pin 2 and the ground (> 10 megohms)
. pin 4 and the ground (> 10 megohms)
. pin 6 and the ground (> 10 megohms).
- replace the VBV sensor AMM 75-31-70-000-001 and AMM 75-31-70-400-001.
- reconnect the harness CJ11L (VBV-A connector) to the VBV sensor (RVDT),
- disconnect the harness J11 from the ECU (4000KS) receptacle and visually examine the J11 harness connector and the VBV sensor (RVDT) receptacle for damaged pins and contamination AMM 73-21-50-210-001.
- repair or replace as required.
- do an electrical resistance test through the J11 harness between:
. pins 13 and 29 (80 to 110 ohms)
. pins 30 and 31 (80 to 120 ohms)
. pins 15 and 32 (85 to 120 ohms)
. pins 13 and 14 (> 10 megohms)
. pins 30 and 14 (> 10 megohms)
. pins 15 and 14 (> 10 megohms)
. pin 13 and the ground (> 10 megohms)
. pin 30 and the ground (> 10 megohms)
. pin 15 and the ground (> 10 megohms).
- replace the ECU (4000KS) AMM 73-21-60-000-001 and AMM 73-21-60-400-001.
- disconnect the J11 harness (located at the 6 o'clock junction box) from the CJ11L and do an electrical resistance test through the CJ11L harness between:
. pins 5 and 6 (80 to 110 ohms)
. pins 2 and 7 (80 to 120 ohms)
. pins 3 and 4 (85 to 120 ohms)
. pins 5 and 1 (> 10 megohms)
. pins 2 and 1 (> 10 megohms)
. pins 3 and 1 (> 10 megohms)
. pin 5 and the ground (> 10 megohms)
. pin 2 and the ground (> 10 megohms)
. pin 3 and the ground (> 10 megohms).
- replace the CJ11L harness AMM 73-21-50-000-010 and AMM 73-21-50-400-010.
- replace the J11 harness AMM 73-21-50-000-010 and AMM 73-21-50-400-010.
A. The failure message is generated if the channel A signal is invalid, out of range, or both channels disagree.
(1) If the failure message VBV SNSR, J11, ECU is not confirmed:
(a) No maintenance action is required.
(2) If the failure message VBV SNSR, J11, ECU is not confirmed but is repetitive:
Subtask 75-30-00-810-063-C ** ON A/C NOT FOR ALL (1) If the failure message VBV SNSR, J11, ECU is not confirmed:
(a) No maintenance action is required.
(2) If the failure message VBV SNSR, J11, ECU is not confirmed but is repetitive:
- disconnect the CJ11L harness from the VBV sensor (VBV-A connector) located in the left core compartment and visually examine the receptacle and the harness for damaged pins and contamination AMM 73-21-50-210-001.
- repair or replace as required.
- replace the
VBV sensor (RVDT) AMM 75-31-70-000-001 and AMM 75-31-70-400-001.
NOTE: After new VBV sensor is installed, a rigging of the VBV system is required AMM 75-31-00-200-001.
(c) If the fault continues during the subsequent flights: - disconnect the J11 harness from the ECU (4000KS) and visually examine the receptacle and the connector for damaged pins and contamination AMM 73-21-50-210-001.
- repair or replace as required.
- replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.
- replace the harness J11 (ECU to the 6 o'clock junction box) AMM 73-21-50-000-010 and AMM 73-21-50-400-010.
- replace the harness CJ11L (located in the left core compartment) AMM 73-21-50-000-001 and AMM 73-21-50-400-001.
- disconnect the CJ11L harness from the VBV sensor (VBV-A connector) located in the left core compartment and visually examine the CJ11L harness connector and the VBV sensor (RVDT) receptacle for damaged pins and contamination AMM 73-21-50-210-001.
- repair or replace as required.
- do an electrical resistance test through the VBV sensor between:
. pins 2 and 3 (80 to 110 ohms)
. pins 4 and 5 (80 to 120 ohms)
. pins 6 and 7 (85 to 120 ohms)
. pin 2 and the ground (> 10 megohms)
. pin 4 and the ground (> 10 megohms)
. pin 6 and the ground (> 10 megohms).
- replace the VBV sensor AMM 75-31-70-000-001 and AMM 75-31-70-400-001.
- reconnect the harness CJ11L (VBV-A connector) to the VBV sensor (RVDT),
- disconnect the harness J11 from the ECU (4000KS) receptacle and visually examine the J11 harness connector and the VBV sensor (RVDT) receptacle for damaged pins and contamination AMM 73-21-50-210-001.
- repair or replace as required.
- do an electrical resistance test through the J11 harness between:
. pins 13 and 29 (80 to 110 ohms)
. pins 30 and 31 (80 to 120 ohms)
. pins 15 and 32 (85 to 120 ohms)
. pins 13 and 14 (> 10 megohms)
. pins 30 and 14 (> 10 megohms)
. pins 15 and 14 (> 10 megohms)
. pin 13 and the ground (> 10 megohms)
. pin 30 and the ground (> 10 megohms)
. pin 15 and the ground (> 10 megohms).
- replace the ECU (4000KS) AMM 73-21-60-000-001 and AMM 73-21-60-400-001.
- disconnect the J11 harness (located at the 6 o'clock junction box) from the CJ11L and do an electrical resistance test through the CJ11L harness between:
. pins 5 and 6 (80 to 110 ohms)
. pins 2 and 7 (80 to 120 ohms)
. pins 3 and 4 (85 to 120 ohms)
. pins 5 and 1 (> 10 megohms)
. pins 2 and 1 (> 10 megohms)
. pins 3 and 1 (> 10 megohms)
. pin 5 and the ground (> 10 megohms)
. pin 2 and the ground (> 10 megohms)
. pin 3 and the ground (> 10 megohms).
- replace the CJ11L harness AMM 73-21-50-000-010 and AMM 73-21-50-400-010.
- replace the J11 harness AMM 73-21-50-000-010 and AMM 73-21-50-400-010.
A. The failure message is generated if the channel A signal is invalid, out of range, or both channels disagree.
(1) If the failure message VBV SNSR, J11, ECU is not confirmed:
(a) No maintenance action is required.
(2) If the failure message VBV SNSR, J11, ECU is not confirmed but is repetitive:
Subtask 75-30-00-710-077-A ** ON A/C NOT FOR ALL (1) If the failure message VBV SNSR, J11, ECU is not confirmed:
(a) No maintenance action is required.
(2) If the failure message VBV SNSR, J11, ECU is not confirmed but is repetitive:
- disconnect the CJ11L harness from the VBV sensor (VBV-A connector) located in the left core compartment and visually examine the receptacle and the harness for damaged pins and contamination AMM 73-21-50-210-001.
- repair or replace as required.
- replace the
VBV sensor (RVDT) AMM 75-31-70-000-002 and AMM 75-31-70-400-002.
NOTE: After new VBV sensor is installed, a rigging of the VBV system is required AMM 75-31-00-200-002.
(c) If the fault continues during the subsequent flights: - disconnect the HJ11 harness from the ECU (4000KS) and visually examine the receptacle and the connector for damaged pins and contamination AMM 73-21-50-210-001.
- repair or replace as required.
- replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.
- replace the harness HJ11 (ECU to the 6 o'clock jonction box) AMM 73-21-50-000-044 and AMM 73-21-50-400-044.
- replace the harness CJ11L (located in the left core compartment) AMM 73-21-50-000-025 and AMM 73-21-50-400-025.
- disconnect the CJ11L harness from the VBV sensor (VBV-A connector) located in the left core compartment and visually examine the CJ11L harness connector and the VBV sensor (RVDT) receptacle for damaged pins and contamination AMM 73-21-50-210-002.
- repair or replace as required.
- do an electrical resistance test through the VBV sensor between:
. pins 2 and 3 (80 to 110 ohms)
. pins 4 and 5 (80 to 120 ohms)
. pins 6 and 7 (85 to 120 ohms)
. pin 2 and the ground (> 10 megohms)
. pin 4 and the ground (> 10 megohms)
. pin 6 and the ground (> 10 megohms).
- replace the VBV sensor AMM 75-31-70-000-002 and AMM 75-31-70-400-002.
- reconnect the harness CJ11L (VBV-A connector) to the VBV sensor (RVDT),
- disconnect the harness HJ11 from the ECU (4000KS) receptacle and visually examine the HJ11 harness connector and the VBV sensor (RVDT) receptacle for damaged pins and contamination AMM 73-21-50-210-002.
- repair or replace as required.
- do an electrical resistance test through the J11 harness between:
. pins 13 and 29 (80 to 110 ohms)
. pins 30 and 31 (80 to 120 ohms)
. pins 15 and 32 (85 to 120 ohms)
. pins 13 and 14 (> 10 megohms)
. pins 30 and 14 (> 10 megohms)
. pins 15 and 14 (> 10 megohms)
. pin 13 and the ground (> 10 megohms)
. pin 30 and the ground (> 10 megohms)
. pin 15 and the ground (> 10 megohms).
- replace the ECU (4000KS) AMM 73-21-60-000-001 and AMM 73-21-60-400-001.
- disconnect the HJ11 harness (located at the 6 o'clock junction box) from the CJ11L and do an electrical resistance test through the CJ11L harness between:
. pins 5 and 6 (80 to 110 ohms)
. pins 2 and 7 (80 to 120 ohms)
. pins 3 and 4 (85 to 120 ohms)
. pins 5 and 1 (> 10 megohms)
. pins 2 and 1 (> 10 megohms)
. pins 3 and 1 (> 10 megohms)
. pin 5 and the ground (> 10 megohms)
. pin 2 and the ground (> 10 megohms)
. pin 3 and the ground (> 10 megohms).
- replace the CJ11L harness AMM 73-21-50-000-025 and AMM 73-21-50-400-025.
- replace the HJ11 harness AMM 73-21-50-000-044 and AMM 73-21-50-400-044.
B. Do the test given in Para. 3.A.
(1) No additional maintenance action is required if the fault is not confirmed.
(2) Repeat the fault isolation procedure if the fault continues.
(1) No additional maintenance action is required if the fault is not confirmed.
(2) Repeat the fault isolation procedure if the fault continues.