Disagree between the N2 Indication and the ECU Output on Engine 1

TASK 77-00-00-810-831-A
Disagree between the N2 Indication and the ECU Output on Engine 1

1. Possible Causes

SENSOR-N2 ROTATIONAL SPD [4001EV]
J7/J8 harness
ECU

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 73-29-00-710-040	Operational Test of the FADEC on the ground (with Engine Motoring)

3. Fault Confirmation
Subtask 77-00-00-710-090-A ** ON A/C NOT FOR ALL

A. Test
(1) Not applicable.

4. Fault Isolation
Subtask 77-00-00-810-070-A ** ON A/C NOT FOR ALL

A. The fault may be triggered with wide N2 fluctuations or due to defective SENSOR-N2 ROTATIONAL SPD [4001EV] or J7/J8 harness.
(1) Read the scheduled maintenance report or class 3 report and check if the message N2 SNSR, J7, ECU or N2 SNSR, J8, ECU is present.

If either message is present, do the related troubleshooting procedure.

(2) If no message is present and engine parameters fluctuations were reported at the same time:

do the applicable troubleshooting procedure for ENG1 N1 fluctuations.

Subtask 77-00-00-710-262-A ** ON A/C NOT FOR ALL

B. Do the operational test of the FADEC on the ground (with engine non motoring) AMM 73-29-00-710-040.
(1) If the test gives the message N2 SNSR, J7, ECU or N2 SNSR, J8, ECU, do the applicable troubleshooting procedure.

[Rev.8 from Aug 2018] 2026.04.04 04:37:31 UTC