Tuesday, September 24, 2013
Fire In The Cockpit
Like fire in a ship at sea, fire in the cockpit can be the scariest emergency you hope you’ll never encounter
Engine fires are perhaps the most common of these, and they're the toughest to handle, as most pilots have few alternatives. Many times, there's little choice but to shut down the engine, turn off the fuel and electrical systems to isolate combustible materials from the flame, and take your chances with an emergency landing.
Not all fuel fires are automatically terminal, however. In ferry flying, we're taught never to fill the cabin ferry tanks to the very top. That's sometimes a tough rule to follow on the Pacific, where the legs can stretch to 2,300 nm, e.g., Honolulu to Pago Pago, American Samoa. Most pilots want every ounce of fuel they can get for such long overwater hops.
Trouble is, if you fill every ferry tank and turn on the heater, the heat outlets for the aft cabin, conveniently located on the floor, can cause avgas in the ferry tanks to expand, work its way around the threads of the three-inch gas cap and seep out onto the top of the tank.
One pilot was flying the Pacific one night in a Cessna 310, pushed the mic button on her Yaesu HF radio to transmit a position report back to San Francisco, and heard a muffled "woof" from somewhere behind her. The portable HFs we use over the ocean create a fairly large spark inside the radio during transmission, and in this instance, that spark was enough to ignite the slick of gas on top of the forward ferry tank.
The pilot looked back, saw tiny flames flickering along the top of the tank, and lacking anything better to put out the fire, used water from a gallon bottle. She knew that was the wrong extinguishing agent, but it was all she had. Fortunately, she got away with it, and the flames died out.
Some manufacturers install firewall shut-off valves and recommend the valve be closed at the first hint of fire to inhibit flames from entering the cockpit. If your aircraft isn't fitted with a shut-off valve, at least make certain the heater is off before opening a vent to drain off the smoke. Otherwise, the suction may pull the fire through the firewall and in on top of you. There's a reason the forward barrier between cockpit and engine is called a firewall. It's designed to protect the cabin from any anomaly out front long enough to allow a pilot time to figure out Plan B.
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