In answer to QMax's question, I know of at least one incident. Not technically an engine failure, but the HEMS air ambulance in London was in the midst of a Helipad take-off a few years back, when they realised in their haste to win medals, they had forgotten to start one of the engines ! Being in the centre of the East End of London, and on a roof-top helipad, in a fairly underpowered Dauphin, I am sure the ability to go visually forward and down to the helipad assisted with the whole recovery to Mother Earth !