Internal Failure of the ECU on Engine 1

TASK 73-20-81-810-880-A
Internal Failure of the ECU on Engine 1

1. Possible Causes

ECU [4000KS]
ECU air cooling system
anti-ice system ducts

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 30-21-49-210-001	Visual Inspection of the Anti-Ice System Tubes, Ducts, and Hoses
AMM 30-21-49-210-040	Visual Inspection of the Anti-Ice System Hoses, Tubes and Ducts
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 75-24-49-210-040	Visual inspection of the ECU Air Cooling Tubes and Ducts
AMM 75-24-49-210-042	Visual Inspection of the ECU Air Cooling Tubes and Ducts

3. Fault Confirmation
Subtask 73-20-81-710-128-A ** ON A/C NOT FOR ALL

A. Do the operational test of the FADEC 1B on the ground (with engine non motoring) AMM 73-29-00-710-040.

4. Fault Isolation
Subtask 73-20-81-810-128-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message ECU (OVERTEMP):
(1) Remove the ECU [4000KS] AMM 73-21-60-000-001.
(2) Do a check of the ECU air cooling system to make sure that the inlet and outlet ports are not clogged AMM 75-24-49-210-042.
(3) Do a check for leakage on the anti-ice system ducts AMM 30-21-49-210-040.
(4) Install the new ECU (4000KS) AMM 73-21-60-400-001.

Subtask 73-20-81-810-128-B ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message ECU (OVERTEMP):
(1) Remove the ECU [4000KS] AMM 73-21-60-000-001.
(2) Do a check of the ECU air cooling system to make sure that the inlet and outlet ports are not clogged AMM 75-24-49-210-040.
(3) Do a check for leakage on the anti-ice system ducts AMM 30-21-49-210-001.
(4) Install the new ECU (4000KS) AMM 73-21-60-400-001.

[Rev.8 from Aug 2018] 2026.04.04 04:35:40 UTC