Fire extinguisher powder inside recip engine

[Nardi Riviera]

Witnessed a carburettor fire on a 182, pilot forgot all he learned about firewalling throttle while cranking starter. Another pilot outside a/c stuck extinguisher inside cowlflaps and killed the fire. Few minutes later they started it and taxied to the hangar. It belched smoke alright, but I wonder what was going on inside the engine.

What happens to cylinders and oil when fresh powder from carburettor area is ingested and burned?

[PC-6]

I don't know what kind of stuff the powder is made of but it is corrosive and should be washed off the engine as soon as practical. It is not recommended to run an engine covered in powder and definitely not a good idea to start the engine if the powder can be ingested!
As for the "keep cranking to suck the fire in" theory, it doesn't always work!
It depends a lot on the design of the carb/airbox...