According to the article they only had a 25° nose down attitude. It
looks alot worse than that in the picture. Since most helicopters of
this size typically lift twice there own weight (when empty). I would
estimate that the maximum theoretical nose down angle whould be 60°.
This gives you a thrust vector component of twice youre vertical
component. However the transmission lube systems would not like this at all.

John Roncallo

As long as you can maintain a vertical component of lift equal to the weight of
the helicopter, you'll be Ok. Either way, that looks like one hell of a
balancing act.

I don't know for sure but that looks like it might not be too much different
from a simple (huh?) hover with a heavy sling load as far as control imputs are
concerned. Of course, I'm probably wrong about that. It's never that easy, if
hovering is considered easy. :-)

Fly Safe,
Steve R.