When demonstrating jackstall on the Gazelle, it was shown in two different conditions - a left turn and a dive to VNE.
A Gazelle could normally tolerate a 2g sustained turn - 60 deg AoB - albeit sacrificing speed through the manoeuvre. So a harder pull was required to get it to jackstall, at which point it would pitch up and roll right - exactly why we did it in a left turn and not a right one.
The dive to VNE used the conditions of the day to calculate the DA and therefore the VNE at 1500' agl. From 2500' agl you dived to VNE with MPS set (14.5 deg collective pitch), usually somewhere between 160 and 168 Kts and then pulled aft cyclic - it usually went into jackstall fairly easily in that condition compared to the turning state.
In both scenarios, you could hold the aircraft in the jackstalled state to show how the aerodynamic back loads on the retreating blade (and therefore lateral jack) had to be reduced before the jack would un-stall.
The AS365 had a LIMIT light and audio warning which we also demonstrated in a left turn but never pulled past that - the two side of the hyd jacks had different cross sectioned pistons so the upper half would 'collapse' before the lower half, making a microswitch on the jack and illuminating the LIMIT light and giving the audio 'bong'.
It seems to have been a design philosophy in Aerospatiale/Airbus helicopters.
My instructor on my QHI course in 1976 decided to do the descending turn demo in a 60 degree RIHT HAND TURN.. The aircraft flicked though inverted and came out almost straight and level. I didn't fly with him again.