Rotax 597 snowmobile engine problem (skidoo skandic wt 600 2004)

Hello

I have a Skidoo skandic wt 600 2004 model with a rotax 597 engine. It blows air out from a small 90degrees tube (outlet) on the crank case on right side (right beneath the carburator intake). Sometimes it sounds like it backfires from this tube. Attached picture is from the rotax 593 ( missing the 90 angled pipe).

Does anyone know if there should be a hose connected to this pipe/tube/outlet or what the purpose of this is ?

Regards Haakon