Helicopters do not get destroyed by being hit by a tank main gun fired at long ranges (2km or more). They will only get damaged. Just tested this to be sure, had a hovering mohawk and shot it with the Slammer main gun. It survived and continued hovering after 2 APFSDS rounds and only started to decent/crash after an HE hit.
Seriously I find it hard to believe a helicopter would be able to survive a direct hit with an HE shell at any range.