Jim Macklin wrote:

Vents are not installed in the direct impact slipstream, so
ice is not usually a problem in a well designed system.

Entertainingly, I had a fuel/ice encounter on an Aztec some years
back. Rather than suffer airborne icing, plain rain water got in
under the cap, and froze in the fuel vent line leading to the
high-pressure underside of the wing. That caused an impressive fuel
leak out the fuel cap as soon as we were airborne (= low pressure
formed above the wing).

- FCHE