Black screen flashes with Huey

Occasionally, when flying the Huey I get screen flashes. It looks like 3/4 the screen left to right is completely black for 1 frame every now and then. Just a flash.

I've only ever seen this with Huey and spent equal time flying jets. It can occur both in cockpit or external camera. It's not just the flickering shadow of blades (though could possibly relate to shadows or some graphical feature.) It's irritating, but otherwise appears harmless.

Wondering if anyone else has noticed this or found the cause?

System is nVidia Geforce 2080 with GSync monitor. No overclocking etc. No issues in other games, and I believe other DCS modules.