Wessex used to have a fuel dump ability. It was possible to do a running take off at 14000lbs (normal hover Take off limit 13600lbs) so it gave you the ability to reduce weight to make landing safe particularly after losing and engine.
I only ever was on a flight once where we had to dump fuel prior to being re-tasked to lift a heavy under-slung load just after we had refuelled. To give us out of ground effect performance.