Neither - it was a manufacturing defect/QA problem - the bush was oversized causing local stresses. The head had less than 1200 hours.
After landing Al had great difficulty controlling the aircraft, as the upper tang (on the failed blade grip) had started to bend upwards causing the aircraft to 'dance' around the place! I think the T-Handles came in useful in the end. God only knows how long it would have been before the blade would have parted company....
