N2 Overspeed

TASK 71-00-00-810-842-A
N2 Overspeed

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 71-00-00-810-834-A	General Troubleshooting Guidelines for Additional Troubleshooting Information
TSM TASK 71-00-00-810-835-A	Component and Harness Intermittent Troubleshooting Procedure for Guidance Troubleshooting Intermittent Faults
TSM TASK 71-00-00-810-852-A	Troubleshoot the Engine after an Auto Acceleration event
AMM 71-00-00-860-814	Shutdown of the Engine
AMM 71-00-00-860-822	Start the Engine (Normal Manual Start)
AMM 71-00-00-860-823	Start the Engine (Normal Automatic Start)
AMM 72-00-00-210-810	Inspection of the Engine after N1/N2 Over Speed Operation
AMM 78-36-00-010-802	Opening of the Thrust Reverser Cowl-Doors
AMM 78-36-00-410-802	Closing of the Thrust Reverser Cowl-Doors

3. Fault Confirmation
Subtask 71-00-00-710-097-A ** ON A/C NOT FOR ALL

A. Not Applicable

NOTE: The Electronic Engine Control (EEC) has detected the N2 speed transducer circuit is out of range or rate in channel A and channel B. The N2 speed transducer is mounted on angle gearbox, located at the 5 o'clock position.

Refer to the general troubleshooting guidelines for additional troubleshooting information (Ref. TSM TASK 71-00-00-810-834).
Refer to the component and harness intermittent troubleshooting procedure for guidance troubleshooting intermittent faults (Ref. TSM TASK 71-00-00-810-835).

(1) If the maintenance message does not come back, examine the harnesses and electrical connectors as described in the component and harness intermittent fault isolation procedure (Ref. TSM TASK 71-00-00-810-835).
(a) If no problems are found, return the engine to service. Monitor the engine for reoccurring maintenance message.
(2) If the maintenance message comes back (hard fault) in channel A and channel B, go to the Para. Fault Isolation.

4. Fault Isolation

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE AFTER SHUTDOWN. THE ENGINE CAN STAY HOT FOR A LONG TIME. IF YOU DO NOT OBEY THIS WARNING, INJURY CAN OCCUR.

WARNING: REFER TO THE MSDS FOR ALL MATERIAL USED AND THE MANUFACTURER'S SAFETY INSTRUCTIONS FOR ALL EQUIPMENT USED. IF YOU DO NOT OBEY THIS WARNING, INJURY CAN OCCUR.

CAUTION: MAKE SURE YOU REMOVE ELECTRICAL POWER FROM THE EEC BEFORE YOU REMOVE THE ELECTRICAL CONNECTORS. IF YOU DO NOT OBEY THIS INSTRUCTION, DAMAGE TO THE EEC CAN OCCUR.

Subtask 71-00-00-810-106-A ** ON A/C NOT FOR ALL

A. Do as follows:
(1) Open the thrust reverser cowl-doors AMM 78-36-00-010-802.
(2) Do a visual inspection of the engine after N1/N2 over speed operation AMM 72-00-00-210-810.
(3) If the engine is serviceable and no problems are found, do the troubleshooting procedure for auto acceleration (Ref. TSM TASK 71-00-00-810-852).
(a) Do the test given in Para. 4.B.

Subtask 71-00-00-710-098-A ** ON A/C NOT FOR ALL

B. Repair Confirmation
(1) Do an engine run to idle to confirm repair of this fault AMM 71-00-00-860-822 or AMM 71-00-00-860-823.
(2) Shutdown the engine AMM 71-00-00-860-814.
(3) On MCDU screen, make sure that the fault is not displayed on ground scan report.

5. Close-up
Subtask 71-00-00-860-056-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.
(1) Make sure that the work area is clean and clear of tools and other items.
(a) Close the thrust reverser cowl-doors AMM 78-36-00-410-802.

[Rev.8 from Aug 2018] 2026.04.04 04:35:03 UTC