Place any empty helicopter in editor, set as flying, named "heli".
Create 2 units, both pilots, grouped; Player unit set init to:
this moveinturret [heli,]; this assignasturret [heli,];
set the other unit's init to:
this moveindriver heli; this assignasdriver heli;
preview mission, 'take controls', attempt landing, get out. works correctly.
restart mission, 'take controls', in Debug exec this:
heli setHit ["engine",1];
land safely and observe no action menu to get out. 'release controls' and both units jump out. seems to happen consistently on any chopper put through these steps.