Loss of the Feedback Signal of the N1 Speed Sensor - Engine 2 - Channel A

TASK 77-10-00-810-829-A
Loss of the Feedback Signal of the N1 Speed Sensor - Engine 2 - Channel A

1. Possible Causes

SENSOR-N1 ROTATIONAL SPD [4000EV]
ECU [4000KS]
J9 harness
HJ9 harness

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	BRUSH - BRISTLED

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.CP2011)	stoddard solvent

C. Referenced Information

REFERENCE	DESIGNATION
AMM 73-21-50-000-008	Removal of the J9 Harness
AMM 73-21-50-000-042	Removal of the HJ9 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 73-21-50-400-008	Installation of the J9 Harness
AMM 73-21-50-400-042	Installation of the HJ9 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 77-11-10-000-001	Removal of the N1 Speed Sensor
AMM 77-11-10-000-002	Removal of the N1 Speed Sensor
AMM 77-11-10-400-001	Installation of the N1 Speed Sensor
AMM 77-11-10-400-002	Installation of the N1 Speed Sensor

3. Fault Confirmation
Subtask 77-10-00-710-106-A ** ON A/C NOT FOR ALL

A. Do the operational test of the FADEC 2A on the ground (with engine non motoring) AMM 73-29-00-710-040.

4. Fault Isolation
Subtask 77-10-00-810-080-A ** ON A/C NOT FOR ALL

A. The failure message is generated if channel A and channel B inputs from the N1 sensor disagree.
(1) If the failure message N1 SNSR, J9, ECU* is not confirmed:
(a) No maintenance action is required.
(2) If the failure message N1 SNSR, J9, ECU* is not confirmed but is repetitive:

disconnect J9 harness from the N1 sensor (N1-A connector).

(a) Visually examine the receptacle and the connector for damaged pins or contamination AMM 73-21-50-210-001.
1 If damage is found:

repair or replace as required.

2 If no damage is found:

do a cleaning of the connector and receptacle using a BRUSH - BRISTLED with stoddard solvent (Material No.CP2011) AMM 73-21-50-210-001.

(b) If the failure continues during the subsequent flights:

replace the SENSOR-N1 ROTATIONAL SPD [4000EV] AMM 77-11-10-000-001 and AMM 77-11-10-400-001.

replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.

(d) If the failure continues during the subsequent flights:

replace the J9 harness AMM 73-21-50-000-008 and AMM 73-21-50-400-008.

(3) If the failure message N1 SNSR, J9, ECU* is confirmed:

disconnect the J9 harness from the N1 sensor (N1-A connector).

(a) Visually examine the receptacle and the connector for damaged pins or contamination AMM 73-21-50-210-001.
1 If damage is found:

repair or replace as required.

2 If no damage is found:

do the electrical resistance test through the N1 sensor (4000EV) (channel A) between:
. pins 1 and 2 (40 to 80 ohms)

for S/N different than 25451 and up:
. pins 1 and 3 (>5 kiloohms)
. pin 1 and the ground (>10 megohms)

for S/N 25451 and up:
. pins 1 and 3 (>10 megohms)
. pin 1 and the ground (>10 megohms).

a If the resistance values are out of the specified limits:

replace the N1 sensor (4000EV) AMM 77-11-10-000-001 and AMM 77-11-10-400-001.

b If the resistance values are in the specified limits:

connect the J9 harness to the N1 sensor.

(b) Disconnect the J9 harness from the ECU (4000KS) and visually examine the receptacle and the connector for damaged pins or contamination AMM 73-21-50-210-001.
1 If damage is found:

repair or replace as required.

2 If no damage is found:

do the electrical resistance test through the J9 harness between:
. pins 16 and 17 (40 to 80 ohms)

for S/N different than 25451 and up:
. pins 16 and 6 (>5 kiloohms)
. pin 16 and the ground (>10 megohms)

for S/N 25451 and up:
. pins 16 and 6 (>10 megohms)
. pin 16 and the ground (>10 megohms).

a If the resistance values are in the specified limits:

replace the ECU (4000KS) AMM 73-21-60-000-001 and AMM 73-21-60-400-001.

b If the resistance values are out of the specified limits:

replace the J9 harness AMM 73-21-50-000-008 and AMM 73-21-50-400-008.

Subtask 77-10-00-810-080-B ** ON A/C NOT FOR ALL

disconnect HJ9 harness from the N1 sensor (N1-A connector).

(a) Visually examine the receptacle and the connector for damaged pins or contamination AMM 73-21-50-210-002.
1 If damage is found:

repair or replace as required.

2 If no damage is found:

do a cleaning of the connector and receptacle using a BRUSH - BRISTLED with stoddard solvent (Material No.CP2011) AMM 73-21-50-210-002.

(b) If the failure continues during the subsequent flights:

replace the SENSOR-N1 ROTATIONAL SPD [4000EV] AMM 77-11-10-000-002 and AMM 77-11-10-400-002.

replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.

(d) If the failure continues during the subsequent flights:

replace the HJ9 harness AMM 73-21-50-000-042 and AMM 73-21-50-400-042.

(3) If the failure message N1 SNSR, J9, ECU* is confirmed:

disconnect the HJ9 harness from the N1 sensor (N1-A connector).

(a) Visually examine the receptacle and the connector for damaged pins or contamination AMM 73-21-50-210-002.
1 If damage is found:

repair or replace as required.

2 If no damage is found:

do the electrical resistance test through the N1 sensor (4000EV) (channel A) between:
. pins 1 and 2 (40 to 80 ohms)

for S/N different than 25451 and up:
. pins 1 and 3 (>5 kiloohms)
. pin 1 and the ground (>10 megohms)

for S/N 25451 and up:
. pins 1 and 3 (>10 megohms)
. pin 1 and the ground (>10 megohms).

a If the resistance values are out of the specified limits:

replace the N1 sensor (4000EV) AMM 77-11-10-000-002 and AMM 77-11-10-400-002.

b If the resistance values are in the specified limits:

connect the HJ9 harness to the N1 sensor.

(b) Disconnect the HJ9 harness from the ECU (4000KS) and visually examine the receptacle and the connector for damaged pins or contamination AMM 73-21-50-210-002.
1 If damage is found:

repair or replace as required.

2 If no damage is found:

do the electrical resistance test through the HJ9 harness between:
. pins 16 and 17 (40 to 80 ohms)

for S/N different than 25451 and up:
. pins 16 and 6 (>5 kiloohms)
. pin 16 and the ground (>10 megohms)

for S/N 25451 and up:
. pins 16 and 6 (>10 megohms)
. pin 16 and the ground (>10 megohms).

a If the resistance values are in the specified limits:

replace the ECU (4000KS) AMM 73-21-60-000-001 and AMM 73-21-60-400-001.

b If the resistance values are out of the specified limits:

replace the HJ9 harness AMM 73-21-50-000-042 and AMM 73-21-50-400-042.

Subtask 77-10-00-710-107-A ** ON A/C NOT FOR ALL

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.

[Rev.8 from Aug 2018] 2026.04.04 04:37:40 UTC