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AS350 B3e course · Emergencies

Fire and smoke

In the air, on the ground, and after an accident

8 minDraft

The essentials

Fire is rare and time-critical. The cases are different:

  • engine fire on the ground — shut down and get out
  • engine fire in flight — get on the ground, fast, as the RFM directs
  • electrical smoke or fire — find and isolate the source, ventilate, land
  • post-crash fire — the one that turns survivable accidents into fatal ones

Crash-resistant fuel systems exist because of the last one.

Sources 1, 2, 3

How fire presents

A fire may announce itself with a warning light, where a detection system is fitted. It may equally arrive as smoke, a smell, abnormal engine readings, heat, or a passenger saying something looks wrong behind them.

Treat any of these as real until shown otherwise. A false alarm costs a precautionary landing; a real fire ignored costs everything.

Sources 1, 4

In-depth

What a fire warning senses

An engine fire detector usually senses heat — an overheat or a rapid temperature rise — in the zone it covers, typically the engine compartment, and nothing outside that zone. A fire in the cabin, the baggage hold or on the transmission deck may give no warning at all.

Which zones your aircraft monitors, whether it has extinguishing, and what the warning is called vary by variant and options. Learn it from the RFM's systems section.

Source 4

In-depth

Engine fire

A fire warning means the detection system has sensed heat in the engine bay. Confirm it if you can — smoke, TOT, other indications — but don't wait long: the urgency in flight is to land.

On the ground, shutting the engine down and leaving the aircraft comes before anything else.

Sources 1, 5

In-depth

Why minutes matter

In a helicopter the engine sits close to the main gearbox, the flight-control runs and the tail drive. A fire there can attack the things that keep the aircraft flyable, not just the engine.

That is why fire procedures put getting on the ground first, and why the choice of landing site gets simpler: near beats perfect.

Sources 1, 5

In-depth

Electrical smoke

Acrid smoke without an engine fire warning usually points to electrical trouble. The usual principle is to remove power from the suspect system — or from everything non-essential — then ventilate and land.

Remember what the FADEC and the instruments need before switching things off. The RFM procedure tells you what is safe to shed.

Sources 4, 5

In-depth

Smoke in the cabin

Smoke takes away the two things you fly with: sight of the instruments and sight outside. It also makes everyone on board want to do something.

Ventilation helps visibility, but moving air can also feed a fire, which is why the RFM's procedure is specific about vents and doors. Keep the passengers in their seats and belted; the evacuation comes after the landing.

Sources 1, 6

In-depth

Fire on the ground

One kind of ground fire starts with the engine: unburnt fuel after an aborted or hung start can burn in the exhaust, which is why turbine start procedures commonly include clearing it after an aborted start — as your RFM directs. Refuelling and hot work around the aircraft bring their own risks.

With the rotor turning, getting people out is itself dangerous. Who goes where, and when, is part of the brief.

Sources 5, 6

In-depth

Post-crash fire and fuel systems

In a survivable accident the fuel tank decides a lot. The AS350's original tank was certificated before the US crash-resistance rule (14 CFR 27.952). After Frisco, where the impact was survivable and the fire was not, the NTSB recommended crash-resistant systems, and the US now requires them on newly manufactured helicopters.

Retrofits exist for the AS350 family. Know whether the aircraft you fly has one.

Sources 2, 7, 8, 9

In-depthCase study

A related type, a survivable crash

In the 2018 EC130 B4 accident in the Grand Canyon, all seven people on board survived the impact. The fire that followed killed five of them; the NTSB found the helicopter was not equipped, nor required to be, with a crash-resistant fuel system.

What it teaches

In survivable accidents, the minutes after impact decide who lives. A crash-resistant fuel system and a practised evacuation are both part of surviving them.

Sources 3, 10

What kills most people in survivable helicopter accidents involving fire?

You smell acrid smoke with no fire warning. What's most likely?

In-depth

What does a fire warning detector actually sense?

In-depth

Why does an engine fire in a helicopter make the landing so urgent?

Sources

  1. Helicopter Flying Handbook (FAA-H-8083-21B) · FAA · Chapter 5, Rotorcraft Flight Manual
  2. Aircraft Accident Report AAR-17/01, Airbus AS350 B3e N390LG, Frisco, Colorado · NTSB · 3 July 2015
  3. Aviation Investigation Final Report WPR18MA087 (Eurocopter EC130 B4 N155GC, Peach Springs, Arizona) · NTSB · 10 February 2018; Analysis and Survival aspects
  4. Aviation Maintenance Technician Handbook — Airframe (FAA-H-8083-31B) · FAA · Chapter 17, Fire Protection Systems, p. 17-1 (fire zones, detection methods)
  5. Helicopter Flying Handbook (FAA-H-8083-21B) · FAA · Chapter 4, Helicopter Components, Sections, and Systems
  6. Helicopter Flying Handbook (FAA-H-8083-21B) · FAA · Chapter 8, Ground Procedures and Flight Preparations
  7. 14 CFR 27.952, Fuel system crash resistance · U.S. eCFR
  8. Safety Recommendations A-17-008 through -011 · NTSB · 13 April 2017
  9. FAA Reauthorization Act of 2018 (Pub. L. 115-254) · U.S. Congress · Section 317, Helicopter fuel system safety
  10. Grand Canyon air tour: tailwind, LTE and post-crash fire · Aerossurance · EC130 B4 N155GC, 10 February 2018

Educational only. Not approved training material, and never a substitute for the Rotorcraft Flight Manual, an instructor, or your operator's procedures. Figures marked as manufacturer data or test results are not limitations. This content is a draft and has not yet been reviewed by an instructor.