Jul 31, 2021
RAY: Back in the early days of aviation, aircraft mechanics were often confused by the fact that the engines seemed to backfire through the carburetors with some kind of regularity. In some cases, this would cause damage to the carburetors. At the very least, it would require more maintenance and cleaning of the carburetor, not to mention scaring the pants off the passengers!
The mechanics began investigating, figuring there was something wrong. After thorough investigations and recalibrating of the engines, they discovered that the cause of the backfiring was...the pilot.
In fact, the pilot was doing it on purpose.
The question is: Why would the pilot of the plane want the engine to backfire through the carburetor?
RAY: Well, back in the early days, before they had figured out this phenomenon when pilots flew under damp and cool conditions, the carburetors would ice up.
So the pilots would make it backfire to blow the ice out.
They would either lean out the mixture or advance the timing or do whatever it took to get the thing to pop back through the carburetor, thus expelling the ice which, if it were allowed to build up, would eventually stall the engine and then seize. That would not be good. And, of course, airplane engines don't really have carburetors anymore. But that's why they did it.