By definition, electrical fires originate from electrical components. Often, we can detect an electrical fire before it really gets going. The first clue might be an over-voltage warning light, a higher than normal electrical load, or a popped circuit breaker. The acrid smell of hot insulation or visible white smoke also are common indicators — but don't be fooled. In one incident, white smoke filled the cabin of a Piper Arrow, leading the pilot and instructor to think they had an electrical fire. In reality, they had a fuel fire in the engine compartment, which had begun to melt the ducts that supply heated air to the cabin.
Once ignited, electrical fires burn just like any fire. One difference is that the heat from the energized electrical wiring or component that caused the fire might sustain it. For this reason, your first step if you have an electrical fire is to cut the power by turning off the master switch. By isolating the battery and alternator/generator, we remove the ignition source, and the fire should extinguish.
If the fire is already burning hot, cutting the power won't be enough. You'll need to use an extinguisher to squelch the flames — a tricky proposition if the fire is behind the instrument panel. Once the fire is out, some checklists suggest that we try to restore power and isolate its cause.
We can shut off all our electrical components, turn the master switch back on, and start turning on essential components one at a time. With any luck, a non-critical item will be the culprit, and we can continue on to land at the nearest airport.
Because reenergizing the circuits might recreate the situation that caused the fire in the first place, finding its cause might not be the best option. Another school of thought says we should communicate before cutting the power — if we have time — then refrain from reenergizing the system and possibly restarting the fire. This might mean a no-flap landing or lowering the landing gear manually, but it sure beats incapacitation and an early grave. It's a difficult decision to make, especially if we're on a night flight or in instrument conditions. A good flashlight (or three or four), a handheld transceiver, and a handheld GPS navigation receiver can come in real handy if a fire puts the electrical system out of commission.
If we have time to communicate before powering down the electrical system, we have three options. Call ATC, broadcast in the blind on the emergency frequency of 121.5 MHz, or tune the 7700 emergency code into the transponder and IDENT. Taking a few seconds to do any of these things before we shut down the electrical system might alert someone to the problem and bring fire/rescue services to the scene as we head for an airport. Finally, if it has a manual switch, we can activate the emergency locator transmitter. The beauty of the ELT is that it has its own power supply and will bring help to the scene of a forced landing should that become necessary.
Managing the smoke is another important part of dealing with an electrical fire. Here, too, you'll find different schools of thought. To continue breathing and to see well enough to maintain control of the aircraft, we might have to open the vents or vent window. Opening the pilot's vent window could be a mistake because it might pull the smoke right in front of the pilot, obscuring his vision.
Opening another vent, if available, or cracking a door might be a better option. Venting the smoke may improve breathing and vision — but it can also fan the fire's flames with fresh air. If this happens we have no option but to close the vents.
Regardless of how we handle the electrical system following a fire, continuing the flight any longer than is necessary is out of the question. An in-flight fire is extremely dangerous, and you must land immediately — at the nearest airport, if possible — but possibly at an appropriate off-airport site.
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this as DEATH ZONE...
