Engine Stall

Article 01 described the compressor as a machine that passes air rearward through queues of blades; article 03 installed two sets of anti-surge hardware; article 05 wrote four layers of protection logic. This article is the script for when all of that fails to stop it — or cannot act in time. The handling skeleton is minimal: retard → read the parameters → decide stay-or-go. The real craft is in three distinctions: FADEC-detected versus crew-detected (the two entrances), transient versus persistent (the relight-consideration divide), and what FUEL ADJUSTED is doing on your behalf.

1. Recognition: five signatures

"A stall may be indicated by varying degrees of abnormal engine noises, accompanied by flame from the engine exhaust (and possibly from engine inlet in severe cases), fluctuating parameters, sluggish or no thrust lever response, high EGT and/or a rapid EGT rise when thrust lever is advanced. Engine stalls must be reported for maintenance action."

Each signature has its mechanism pedigree (synthesis, linked back): the noises and exhaust flame are reversed flow — article 01's queue collapsing, combustion gas erupting from both ends; flame from the inlet marks the severe case where the reversal punches all the way forward. Fluctuating parameters are P30 and friends oscillating between stall and recovery. Sluggish lever response is a compressor that cannot swallow the air its fuel flow assumes. And EGT rising as the lever advances is the cruellest trap in the set: too little air, too much fuel, incomplete combustion overloading the hot section — instinct says add thrust to recover what's missing, and instinct pours fuel on the fire.

Note the closing sentence's standing order: every stall is reported for maintenance — recovery in the air never closes the case.

2. Two entrances, one script

2.1 Entrance one: the FADEC detects it (ECAM ENG 1(2) STALL)

"If stall detected by FADEC — In flight — For aircraft equipped with RR engines: FUEL ADJUSTED — Fuel/Air ratio is automatically decreased until the stall disappears. — THR LEVER (AFFECTED ENGINE) IDLE / ENG PARAMETERS CHECK — If abnormal ENG parameters: ENG MASTER OFF."

FUEL ADJUSTED is article 05's "fuel follows P30" caught in the act: the instant P30 collapsed, the FADEC already cut fuel to match what the compressor can actually swallow, and is running on reduced limits to help the engine back out of stall — the first round of rescue was finished before you touched the lever. The stall-recovery protection's "released by lever movement" clause is honoured here too: the protection waits for your procedural retard as the formal acknowledgement. On the ground, the same entrance ends simply: lever idle, MASTER OFF.

2.2 Entrance two: you find it first (the QRH paper procedure)

"If stall detected before the ECAM activation: Refer to PRO-ABN-ENG [QRH] ENG STALL."

The QRH script shares the skeleton and adds a recovery test:

"THR LEVER IDLE / ENG PARAMETERS CHECK — If abnormal ENG parameters: ENG MASTER OFF (Note: If the flight crew suspects that the stall was transient, they can consider an engine relight.) — If normal ENG parameters: ENG ANTI-ICE ON / WING ANTI-ICE ON — Operation of the engine and wing anti-ice will increase the stall margin but EGT will increase accordingly. — THR LEVER SLOWLY MOVE FORWARD — If stall does not recur: CONTINUE NORMAL ENG OPERATION."

"Anti-ice ON to increase the stall margin" is the most thought-provoking counter-intuition in this article (synthesis): anti-ice draws HP3 bleed (article 03) — extracting a stream of air from behind the compressor's congested middle is opening a relief gate, functionally another set of bleed valves. The price is the energy that stream carries away: EGT floats upward accordingly. The slow lever advance is then a recurrence test under the new margin: pass, and the engine stays in service; fail, and you are back at the shutdown line.

3. The anti-surge system, complete — the chapter's through-line closed

And the both-engines instinct (synthesis, toward article 31): two independent compressors choking simultaneously almost never share an aerodynamic cause — the common denominator is more likely fuel (contamination attacking both metering systems — the double SLOW RESPONSE fingerprint of article 19, the FUEL CONTAMINATED trigger of article 31) or a shared environment (volcanic ash, heavy hail — the all-engines world of article 33).

4. Scenario walk-throughs

A bang in the climb, N1 swinging. Retard, watch the parameters — and when FUEL ADJUSTED appears, know the FADEC moved before you did.

Parameters stabilise. Both anti-ice on, lever forward slowly; pass the test and the engine stays in service — and the stall still goes in the report, every time.

Stall during start. That belongs to article 23's territory — a harder air source via crossbleed is the usual cure.

Single-engine stall after hail penetration. Article 05's rain/hail logic is already fighting (N3 raised, igniters on, valves open); your procedure stacks on top of it.

Self-test

[!note]- Q1. EGT rises rapidly as you advance the lever. What does it mean, and what do you do? The classic stall trap — too little air, too much fuel, incomplete combustion. Retard to IDLE; adding thrust pours fuel on the fire.

[!note]- Q2. FUEL ADJUSTED is displayed and you haven't acted yet — what has the FADEC done? Already decreased the fuel/air ratio automatically until the stall disappears (P30-following fuel cut, reduced-limit running). Your procedural retard doubles as the stall-recovery protection's release acknowledgement.

[!note]- Q3. Parameters normal — the three-step recovery test? Both anti-ice ON (HP3 extraction = an extra relief gate, more stall margin at the price of higher EGT) → lever forward slowly → no recurrence = continue normal operation.

[!note]- Q4. Shut down on abnormal parameters — is that the end? Not necessarily — if the flight crew suspects that the stall was transient, they can consider an engine relight (article 26 for the procedure and envelope).

[!note]- Q5. Both engines report STALL almost together — first association? Common cause — fuel (contamination, article 31) or environment (ash/hail, article 33). Purely aerodynamic stalls almost never synchronise across two engines.

Key takeaways

References

• FCOM PRO (engine abnormal procedures: ENG 1(2) STALL complete section — signatures, FUEL ADJUSTED, in-flight/ground branches, QRH entrance) — quoted verbatim.
• QRH (engine stall) — the transient-relight note, the anti-ice margin step with its EGT price, the slow-advance test, the continue-operation ending.
• Integrative synthesis (marked in text): the signature-mechanism links and the EGT trap; the HP3 relief-gate explanation of the anti-ice step; the common-cause direction for dual stalls.

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.