Engine Failure — Trigger, SHAFT FAILURE Auto-Shutdown, Thrust Asymmetry

After the start-phase faults (18/19), this article covers an in-flight single-engine failure: identifying and handling a loss of thrust (flame-out or mechanical failure). It is one of the core engine emergencies. The relight attempt is opened separately in Relight.

1. ENG FAIL trigger

ENG 1(2) FAIL — ANNUNCIATIONS Triggering Conditions: This alert triggers when engine core speed is below idle with MASTER sw ON, and FIRE pb not pushed.

Per PRO-ABN-ENG, ENG 1(2) FAIL triggers when engine core speed is below idle, with MASTER ON and the FIRE pb not pushed.

[!note]- The three trigger elements (synthesis) ① core speed < idle — the engine has actually run down (failure/flame-out); ② MASTER ON — the crew did not shut it down (excludes a normal shutdown); ③ FIRE pb not pushed — excludes a fire shutdown. Together: an unexpected run-down = ENG FAIL.

2. SHAFT FAILURE — Trent auto-shutdown

LAND ASAP. In the case of SHAFT FAILURE (for RR engines): The FADEC automatically shuts down the engine.

Per PRO-ABN-ENG: LAND ASAP, and on a SHAFT FAILURE (RR engines) the FADEC automatically shuts the engine down.

[!warning]- A Trent shaft failure self-shuts down — the three-spool protection On a Rolls-Royce (Trent) shaft failure the FADEC shuts down automatically (PRO-ABN-ENG). In a three-spool engine a shaft break unloads its turbine, which would instantly overspeed — catastrophic. The FADEC cuts fuel and shuts down (related to 30 and 11). A Trent-specific safety design; the crew follows the ECAM.

3. Take-off phase handling

During takeoff phase: L/G ... UP; THR LEVER (AFFECTED ENGINE) ... IDLE; ENG MASTER (AFFECTED ENGINE) ... OFF; ENG FIRE P/B (AFFECTED ENGINE) ... PUSH; AGENT 1 ...

Per PRO-ABN-ENG, in the take-off phase: gear UP, then THR LEVER (affected) IDLE, ENG MASTER OFF (secure); if accompanied by fire, ENG FIRE pb PUSH + AGENT 1 (12 8 actions + ATA 26).

4. Thrust asymmetry

If an engine failure occurs at low speed, the resultant yaw may be significant... To regain or maintain directional control on the runway, it is necessary: ‐ To immediately reduce all thrust levers to IDLE, which will reduce the thrust asymmetry caused by the failed engine ‐ To select all reverse...

Per FCTM PR-AEP-ENG, a low-speed engine failure can produce significant yaw; to keep directional control, immediately reduce all thrust levers to IDLE (reducing the asymmetry) and select reverse. (This is the rejected-take-off case; in-flight directional control is by rudder trim — see ECAM + FCTM.)

5. Relight decision and counterintuitive points

Whether to relight after ENG FAIL depends on damage / no damage: no damage, a relight may be attempted; with damage / SHAFT FAILURE, secure and do not relight. The relight envelope and procedure are in Relight.

 ENG 1(2) FAIL (core < idle + MASTER ON + FIRE not pushed)
   │ LAND ASAP
   ├─ SHAFT FAILURE (RR) → FADEC auto-shutdown
   ├─ take-off phase → gear UP / THR IDLE / MASTER OFF / (if fire) FIRE PUSH + AGENT
   ├─ thrust asymmetry → rudder trim (low-speed RTO: all THR IDLE + reverse)
   └─ relight decision (damage?) → 21

[!warning]- A Trent shaft failure self-shuts down — no prior crew action SHAFT FAILURE (RR) → FADEC auto-shutdown (PRO-ABN-ENG) — preventing post-break turbine overspeed. The crew follows the ECAM.

[!warning]- ENG FAIL needs MASTER ON + FIRE not pushed to trigger The trigger includes MASTER ON + FIRE pb not pushed (PRO-ABN-ENG) — distinguishing an unexpected run-down from a deliberate or fire shutdown.

Self-test

[!note]- Q1. The ENG 1(2) FAIL trigger? Engine core speed < idle + MASTER ON + FIRE pb not pushed.

[!note]- Q2. What does the FADEC do on a Trent shaft failure? Automatically shuts the engine down (SHAFT FAILURE for RR engines) — preventing turbine overspeed.

[!note]- Q3. The take-off-phase handling sequence? Gear UP → THR LEVER (affected) IDLE → ENG MASTER OFF → (if fire) ENG FIRE PUSH + AGENT.

[!note]- Q4. How is asymmetry controlled at low speed? Immediately all thrust levers to IDLE to reduce the asymmetry + select reverse (RTO).

Key takeaways

References

• FCOM PRO-ABN-ENG — ENG 1(2) FAIL trigger (core < idle + MASTER ON + FIRE not pushed); LAND ASAP; SHAFT FAILURE (RR) FADEC auto-shutdown; take-off-phase handling.
• FCTM PR-AEP-ENG — low-speed engine-failure thrust asymmetry: all THR IDLE + reverse.

Independent study material, not an Airbus publication and not endorsed by the manufacturer. Always defer to the current operator FCOM, FCTM, and QRH for operational use.