Start & Ignition Faults

Article 12 described the five start diseases the FADEC watches for, and the dry-crank-and-retry script it performs by itself. This article is that monitoring's alert face and the manual continuation: what the human does when the automatic script has played out and the engine still won't start (a 30-second manual dry crank, a crossbleed start, the start-valve hand crank); plus the three-step degradation ladder on the ignition side (one circuit lost → both lost → the emergency supply lost).

File one curiosity first: the two-engine ENG START FAULT and the single-engine ENG 1(2) START FAULT are entirely different illnesses sharing a name — the two-engine version is merely "your thrust levers aren't at idle for the start"; the single-engine version is the real disease.

1. ENG START FAULT (two-engine version) — a false alarm about your hand

"This alert triggers when all thrust levers are not at idle during engine start. — THR LEVERS NOT AT IDLE / THR LEVERS IDLE."

Same name as the single-engine alert, utterly different nature: this one polices your hand, not the engine — the opening configuration of article 12's start sequence wasn't set.

2. ENG 1(2) START FAULT — six triggers, five subtitles, three paths

"This alert triggers when one of the following conditions is detected: ‐ Starter time exceeded, or ‐ Stall, or ‐ EGT overlimit, or ‐ No light up, or ‐ Low N1, or ‐ THR levers not at idle."

This is article 12's five diseases in alert form — the hot start appears under the EGT OVERLIMIT subtitle, the hung start as STARTER TIME EXCEEDED, the locked rotor as LOW N1. The handling forks three ways by scenario:

In flight (stall / EGT / no light-up):

"ENG MASTER (AFFECTED ENGINE) OFF — Wait 30 s before a new start attempt (to drain the engine)."

The 30 seconds buy working time for the dump valve of article 09 — clearing the combustor so the next light-off doesn't become a torching.

On ground, automatic start. First, look for NEW START IN PROGRESS — article 12's automatic dry-crank-and-retry script is mid-performance; don't interrupt it. If it still fails → MASTER OFF ("Fuel metering valve and starter air valve are automatically closed. Both igniters are turned off."), plus the sentence worth its weight:

"In the case of stall consider X BLEED start if pressure is low."

A common cause of start stall is insufficient starter air pressure — the rotor won't spool up far enough, leaving the fuel-air ratio relatively rich (synthesis, via article 12's three air sources and the starter-inlet pressure indication of article 15). Swapping in a harder air source — crossbleed from the other engine — often cures it.

On ground, manual start fails. MAN START OFF + MASTER OFF → selector to CRANK + MAN START ON, dry crank 30 seconds ("The start valve reopens automatically when N3 below 10 %" — the dry crank must wait for the rotor to fall below 10 % before the start valve will reopen) → "The flight crew must decide whether to attempt a new start or report". In manual mode, retry-or-quit is the human's call — the FADEC's automatic script belongs to automatic starts only.

LOW N1 (rotor confirmed locked on the ground) and STARTER TIME EXCEEDED: both close the case — lever idle / MAN START OFF / MASTER OFF. The first gets no second attempt (article 12); the second is the alert face of the starter duty-cycle limits in article 00.

3. START VALVE FAULT — three subtypes, three repair philosophies

"This alert triggers when the start valve is jammed (in closed or open position), or no starter air pressure is available."

The three philosophies line up neatly (synthesis): fix the door, send the air, cut the air. A jammed-shut door gets opened by hand; a door short of air gets supplied; a door that won't close — since it cannot be shut, make sure there is nothing behind it to leak. What the cut-the-air list protects is the moment article 00's "no starter engagement while running" limit guards: the clutch pawls.

4. The ignition ladder — three steps down

"ENG 1(2) IGN A(B) FAULT — This alert triggers when ignition circuit A or B is failed. If on the same engine the second igniter is inoperative: AVOID ADVERSE WEATHER. INOP SYS: ENG 1(2) IGN A(B)."

"ENG 1(2) IGN A+B FAULT — This alert triggers when both ignition circuits are failed. AVOID ADVERSE WEATHER. INOP SYS: ENG 1(2) IGN."

"ENG 1(2) IGN SUPPLY FAULT — This alert triggers when the emergency power supply of the ignition system is lost. Crew awareness."

The ladder's logic, via article 11: one circuit failed — the other igniter remains (the automatic both-igniters substitution is this fact's other face); daily life unaffected. Both circuits failed — this engine has lost its anti-flameout capability: auto-relight and heavy-rain/hail continuous ignition are now empty words. "Avoid adverse weather" decodes as don't take an engine that cannot relight into heavy rain, hail, or severe turbulence. SUPPLY FAULT — the emergency 115 V AC feed to circuit A (article 11's "the seed fire rides the essential bus") is lost; normal power remains and ignition still works. What is gone is the fire seed under emergency electrics — hence mere awareness, an insurance policy quietly lapsed.

This is also why the MEL lists IGN A+B FAULT as its own dispatch item (article 18): losing the second circuit is a qualitative change, not an increment.

5. Scenario walk-throughs

High-elevation airport, APU-bleed start, right engine stalls and aborts. Run the pressure arithmetic (article 15's starter-inlet reference) and remember the X BLEED hint: start the left engine first, then crossbleed-start the right with harder air.

Turnaround, START VALVE NOT CLOSED. Walk the cut-the-air list immediately — and hear article 00's duty-cycle clock ticking on a starter being dragged around against its will.

Dispatched under MEL with IGN A FAULT, weather deviations ahead. Keep the margin ledger in mind: this engine is one failed igniter away from "avoid adverse weather".

In-flight relight won't catch. The 30-second wait is not wasted time — it is buying the next attempt a clean combustor.

Self-test

[!note]- Q1. Two-engine ENG START FAULT vs single-engine — the difference? Two-engine version = thrust levers not all at idle during start (polices your hand). Single-engine version = the real six-condition start disease (polices the engine).

[!note]- Q2. Why wait 30 seconds before a new start attempt in flight? To give the dump valve time to drain the combustor (article 09) — lighting off over pooled fuel is the recipe for a tailpipe fire (article 24).

[!note]- Q3. The standard close-out after a failed manual start on the ground? MAN START OFF + MASTER OFF → selector CRANK + MAN START ON, dry crank 30 seconds (the start valve reopens automatically only below 10 % N3) → the crew decides: retry or report. Manual mode has no FADEC automatic script.

[!note]- Q4. Why does START VALVE NOT CLOSED strip away all the air sources? A valve jammed open means the starter is being continuously air-driven — re-engagement at speed wrecks the clutch pawls and drags the starter to destruction (article 12's error table). If the door won't shut, cut its air: APU bleed, crossbleed, engine bleed, anti-ice, item by item.

[!note]- Q5. After IGN A+B FAULT, what does this engine fear? Flameout — with both circuits gone, auto-relight and continuous ignition are disabled (articles 11/05). Hence AVOID ADVERSE WEATHER: keep it out of heavy rain, hail, and strong turbulence.

Key takeaways

References

• FCOM PRO (engine abnormal procedures: ENG START FAULT both versions; START VALVE FAULT three subtypes; IGN A(B) / IGN A+B / IGN SUPPLY FAULT) — triggering conditions, procedures, and notes quoted verbatim.
• The start-valve manual operation and crossbleed-start procedures themselves live in the supplementary procedures — see article 34.
• Integrative synthesis (marked in text): the X BLEED-cures-start-stall mechanism chain; the fix/send/cut philosophy; the ignition-ladder logic and the MEL-line rationale.

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.