Tailpipe Fire & Abnormal Shutdown

Both scenarios happen on the ground, neither has a dedicated ECAM alert (two of the six paper-QRH cases catalogued in article 18), and both procedures contradict instinct. Pairing them in one article serves a teaching purpose: the two procedures take exactly opposite attitudes to the ENG FIRE pushbutton — the tailpipe fire procedure expressly forbids pressing it (press it and you can no longer blow the fire out), while the won't-shut-down procedure makes it the only switch that works (it force-closes the LP fuel valve). Understand that contradiction and you have genuinely taken the FIRE pushbutton apart into its two separate powers: cutting the FADEC's electrical supply and closing the LP fuel valve.

1. ENGINE TAILPIPE FIRE — a fire you extinguish with wind

1.1 Recognition: a fire with no alert

"Internal engine fire may be encountered during engine start or engine shutdown. It may be seen by the ground crew, or the EGT may fail to decrease after the ENG MASTER lever is turned off."

Why ECAM stays silent (article 17): the fire burns inside the gas path — pooled fuel alight in the combustor, turbine, or exhaust — while the fire detectors stand watch in the zones, the nacelle bays around the outside of the engine. The detectors cannot smell a fire inside the pipe. Your detectors for this fire are the ground crew's eyes and an EGT needle behaving wrongly — the engine is shut down, EGT should be falling, and it isn't: something inside is still burning. The classic causes (synthesis, via articles 09/23): a failed start leaving pooled fuel that the next attempt ignites, or residual fuel at shutdown finding the hot section before the drain chain clears it.

1.2 The procedure: cut fuel, establish air, blow

"ENG MASTER (affected engine) OFF — Note: Do not press the ENG FIRE pb-sw, since this would cut off the FADEC power supply, which would prevent motoring sequence. — ESTABLISH AIR BLEED PRESS: Select the APU, or opposite ENG BLEED, to motor the engine. If APU BLEED is not available, and the other engine is shut down, connect external pneumatic power (if readily available). — BEACON ON — When N3 < 30 %: ENG START sel CRANK / ENG MAN START pb ON (The start valve automatically reopens, when N3 is below 10 %). — When fire stopped: MAN START OFF / sel NORM. Maintenance action is due."

The extinguishing principle is wind (synthesis): what burns in the pipe is pooled fuel, and the best extinguishant is a large flow of cold air. A dry crank — CRANK means no fuel, no ignition (article 12) — turns the compressor into a blower that snuffs the flame and sweeps the vapour out. The whole procedure is article 12's dry crank, repurposed as a fire hose.

The Note is the soul of the piece: pressing the FIRE pushbutton trips the hardwired relay that cuts the FADEC's power (article 06) — and with the FADEC dark, nobody controls the start valve, so the motoring sequence cannot run. Meanwhile the fire bottles' discharge nozzles sit in the nacelle bays (article 02) — they cannot reach a fire inside the duct. Press the button and you have disabled your blower without buying any extinguishant. The N3 < 30 % gate before engaging the starter is the same clutch-pawl protection as article 00's no-engagement-while-running limit.

1.3 External agents: the last resort

"CAUTION: External fire agents can cause severe corrosive damage. Consider the use of external fire agents only if the following procedure does not stop engine tailpipe fire."

Fire-truck powder or foam poured into a hot section most likely writes the engine off — corrosion of the turbine and combustor. Hence the order: blow first; only if blowing fails does the fire service go in. The BEACON ON step reads in the same spirit (synthesis): it warns ground personnel clear, and signals we are handling it.

2. ON GROUND — NON ENG SHUTDOWN AFTER ENG MASTER OFF — the engine that won't die

2.1 Look at the LP valve before you touch anything

"The normal procedure to shut down an engine is to set the ENG MASTER lever to OFF. In the case where the engine does not shut down as expected: ECAM FUEL PAGE SELECT / LP FUEL VALVE POSITION (affected engine) CHECK — If LP fuel valve closed (cross line amber): NO CREW ACTION — If LP fuel valve open: ENG FIRE pb-sw PRESS (Using the engine fire pushbutton will force the LP fuel valve to close.) — GROUND CREW NOTIFY."

The diagnostic logic, via article 09: MASTER OFF should close both the LP and HP valves. The engine is still running — so first separate "the valve didn't close" from "the valve closed but the fuel isn't burned yet". The LP valve symbol on the ECAM FUEL page is the watershed: valve closed (amber cross-line) = the system worked; what remains is line fuel — wait. Valve open = the HP valve is likely compromised too and fuel is still feeding — use the FIRE pushbutton as the second key (article 17: its command line runs straight to the LP valve). This is the only procedure in the entire syllabus where you press the fire pushbutton with no fire.

2.2 The physics of one minute thirty

"IN BOTH CASES, ENGINE WILL SHUT DOWN AFTER A TIME DELAY UP TO 1 MIN 30 S — The engine shuts down when the remaining fuel between the LP fuel valve and the nozzles is burned. The time delay for engine shutdown depends on airport altitude and fuel recirculation system operation."

The LP valve sits at the wing side — the very top of the fuel path in article 09. Close it, and an entire line's worth of fuel still stands between the valve and the spray nozzles; the engine runs on that inventory for a while. One minute thirty is the ceiling of "line volume ÷ idle fuel flow" (synthesis); airport elevation and the fuel recirculation system's state both change how fast the inventory burns down. The teaching value: "I pressed it and the engine is still turning" does not mean "it didn't work" — read the valve symbol on the FUEL page, then give it its ninety seconds.

3. The two procedures side by side — the heart of this article

4. Scenario walk-throughs

Ground crew calls "flames from the tailpipe" during a second start attempt. MASTER already off? Straight into the blow-out procedure — and the APU bleed still connected from the start attempt is exactly the air you need (the worsening branch of article 23's start scenarios).

EGT hangs at 300 °C after shutdown, not falling. Don't wait for the ground call — treat it as the tailpipe-fire recognition cue it is.

Turnaround shutdown, N3 parked at 25 % and turning. FUEL page, valve symbol: amber cross-line means hold your nerve and count — it will die within the ninety seconds.

Debrief line worth keeping: the FIRE pushbutton's two identities — power-cut switch and second key to the LP valve — are precisely what dictate its opposite treatment in these two procedures.

Self-test

[!note]- Q1. Ground crew reports fire at the tailpipe during start, but ECAM says nothing. Contradiction? No — a tailpipe fire burns inside the gas path, and the detectors live in the nacelle zones (article 17); they cannot smell a fire in the pipe. Eyes and a misbehaving EGT are the detectors for this fire.

[!note]- Q2. Why is the FIRE pushbutton forbidden for a tailpipe fire? What extinguishes it? The pushbutton cuts FADEC power (the hardwired relay) → the motoring sequence cannot run; and the extinguisher nozzles are in the nacelle bays, out of reach of the duct. The fire is put out by dry-cranking the engine as a blower — APU, opposite-engine, or external air, starter engaged below 30 % N3.

[!note]- Q3. When does the fire truck step in? Only if the blow-out procedure fails — external agents cause severe corrosive damage to the hot section; "save the fire, lose the engine" is strictly the last resort.

[!note]- Q4. N3 won't drop after MASTER OFF, and the FUEL page shows the LP valve as an amber cross-line. Next step? NO CREW ACTION — the valve is closed; the engine is burning the line fuel between valve and nozzles and will stop by itself within 1 min 30 s.

[!note]- Q5. Which two factors stretch or shrink that 1 min 30 s? Airport altitude and the fuel recirculation system's operation — both change how fast the line inventory burns down (the stated value is the ceiling).

Key takeaways

References

• QRH (Engine Tailpipe Fire; On Ground — Non Engine Shutdown After ENG MASTER OFF) — both paper procedures in full, including the corrosion CAUTION.
• FCOM PRO (engine abnormal procedures, annotated versions of both) — recognition cues, the do-not-press Note, the three air sources, the start-valve reopening threshold, the valve-position watershed, and the 1 min 30 s delay with its two factors, quoted verbatim.
• Integrative synthesis (marked in text): the typical-cause chain; the blower principle and the disabled-blower deduction; the BEACON reading; the valve-vs-line-fuel diagnostic frame; the volume-over-flow ceiling interpretation.

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.