Malabo, the ACN aircraft was not returning to a runway; it was a river side helipad. The loss of control occured during the decelaration on approach.
Interestingly, ECF had a tail rotor failure with the EC-155 during the B1 hot and high trials in Arizona, manifested initially by increasing vibration. They took it back to the nearest runway, having established they had no yaw control. Subsequently they added an emergency procedure to the FLM that stated that in the event of in flight severe vibration, the pilot should establish whether he has yaw control, and if not to resist the temptation to land immediately. Speaking to the pilot concerned, he said it was the worst vibration he had experienced in 25 years of test flying, and the urge to land was overpowering. They carried out a successful running landing after 20 minutes. That is not to question the actions of the pilot in this incident, I hasten to add!
Is this failure a result of cracking of the carbon fibre TT straps? The 155 has titanium ones, partly to address this issue.