ENG CTL SYS FAULT — FADEC Control-System Fault and Start-Transient Reading

FADEC / FADEC Architecture gave the two-channel system. This article is its ECAM presentation — ENG CTL SYS FAULT — and in particular the most common form, a start-sequence transient, and how the crew tells a real fault from a spurious one. It is part of start monitoring.

1. Source — a FADEC control-system anomaly

ENG CTL SYS FAULT reflects an anomaly in the FADEC (EEC) control system. A single-channel fault is normally taken over automatically (02), perhaps with only the CTL SYS FAULT advisory; at start there is a known transient form.

2. The start-transient cause

DESCRIPTION — During engine start, a transient fault may trigger the ENG 1(2) CTL SYS FAULT alert associated with the ENG 1(2) SLOW RESPONSE status information displayed on the STATUS page. This abnormal behavior is due to the EEC that starts the monitoring of Fuel Metering Valve (FMV) too early during the engine start sequence.

Per DSC-70-100 (ENGINES — Temporary Abnormal Behaviors): during start a transient fault may trigger ENG 1(2) CTL SYS FAULT with ENG 1(2) SLOW RESPONSE on the STATUS page, because the EEC begins monitoring the FMV too early — reading "FMV not yet there" as a fault while the engine is in fact fine.

3. Handling — judge spurious by a second start

OPERATIONAL RECOMMENDATIONS — Check the display of the ENG 1(2) SLOW RESPONSE status before setting the ENG MASTER 1(2) lever to off. If the ENG 1(2) SLOW RESPONSE status is displayed: A second engine start can be attempted. CAUTION: A second engine start can be attempted only if the ENG 1(2) SLOW RESPONSE status is displayed. During the second engine start attempt: ‐ If the ENG 1(2) CTL SYS FAULT alert is not triggered, the alert can be considered as spurious…

Per DSC-70-100: before setting ENG MASTER OFF, check whether ENG SLOW RESPONSE is displayed; if it is, a second start may be attempted; only if SLOW RESPONSE is displayed (CAUTION); and if CTL SYS FAULT does not trigger on the second start, treat it as spurious.

[!warning]- The key: check SLOW RESPONSE first, then verify by a second start ① Confirm SLOW RESPONSE before MASTER OFF (the precondition for re-starting); ② only with SLOW RESPONSE displayed is a second start allowed; ③ no re-trigger on the second start = spurious. Don't read a CTL SYS FAULT as a broken engine — verify it with the second start.

4. Escalation — both engines + FMV failure → ENG FUEL CONTAMINATED

The ENG FUEL CONTAMINATED alert triggers 10 s after the following combination of alerts: ‐ Both fuel filters are detected clogged (ENG 1(2) FUEL FILTER CLOG alerts), or ‐ Both ENG 1 CTL SYS FAULT and ENG 2 CTL SYS FAULT alerts associated with ENG 1(2) SLOW RESPONSE in the case of FMV failure.

Per PRO-ABN-ENG, ENG FUEL CONTAMINATED triggers 10 s after either both fuel filters clogged or both engines' CTL SYS FAULT + SLOW RESPONSE (FMV failure). A single CTL SYS FAULT is usually transient/single-channel; both engines together points to FMV failure → possible fuel contamination (a common cause), a more serious signal (→ Fuel Faults).

5. Decision tree and counterintuitive point

 ENG 1(2) CTL SYS FAULT during start
   │ before MASTER OFF, check STATUS page ENG SLOW RESPONSE
   ├─ SLOW RESPONSE displayed → second start may be attempted
   │     └─ not re-triggered → spurious (normal)
   └─ both engines CTL SYS FAULT + SLOW RESPONSE → beware ENG FUEL CONTAMINATED (FMV-failure common cause) → 26

[!warning]- A start-sequence CTL SYS FAULT is often spurious — don't rush to call the engine broken The cause is the EEC monitoring the FMV too early (DSC-70-100) — the engine may be fine. Check SLOW RESPONSE, then verify with a second start; no re-trigger = spurious. But both engines together warns of FMV failure / fuel contamination.

Self-test

[!note]- Q1. The common cause of a start-sequence CTL SYS FAULT? The EEC monitoring the FMV too early in the start sequence → CTL SYS FAULT + ENG SLOW RESPONSE (transient; the engine may be fine).

[!note]- Q2. How is it handled? Check SLOW RESPONSE before MASTER OFF; if displayed, a second start may be attempted; no re-trigger = spurious.

[!note]- Q3. When can a second start NOT be attempted? When SLOW RESPONSE is not displayed (CAUTION: only with SLOW RESPONSE displayed).

[!note]- Q4. What combination escalates to ENG FUEL CONTAMINATED? Both fuel filters clogged, or both engines CTL SYS FAULT + SLOW RESPONSE (FMV failure), 10 s later.

Key takeaways

Point	Detail
CTL SYS FAULT	FADEC/EEC control-system fault; at start often transient (EEC monitors FMV too early)
Handling	check SLOW RESPONSE before MASTER OFF → second start → no re-trigger = spurious
Escalation	both engines CTL SYS FAULT + SLOW RESPONSE → ENG FUEL CONTAMINATED (FMV failure, 10 s)

References

FCOM DSC-70-100 — ENG CTL SYS FAULT start transient (EEC monitors FMV too early) + SLOW RESPONSE; handling (check SLOW RESPONSE before MASTER OFF, verify spurious by a second start).
FCOM PRO-ABN-ENG — ENG FUEL CONTAMINATED: both fuel filters clogged, or both engines CTL SYS FAULT + SLOW RESPONSE (FMV failure), 10 s.

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.