Primary finding
Probable cause
The failure of the tailrotor driveshaft hanger bearing and jamming of the tailrotor.
Investigator assessment
Analysis narrative
The pilot was demonstrating a hovering maneuver during an airshow. During this maneuver, the helicopter began an uncommanded left turn and landed hard causing substantial damage. Inspection revealed that the #1 tailrotor drive shaft hanger bearing failed, then the tailrotor RPM sensor broke loose, and the tailrotor became jammed.
Source record
Factual narrative
On April 9, 2008, at 1200 edt, a Baby Belle, experimental rotorcraft, N6261N, landed hard at Lakeland Linder Regional Airport, Lakeland, Florida, after experiencing a loss of tail rotor effectiveness. The experimental rotorcraft was substantially damaged. The pilot, the only occupant, was not injured. Visual meteorological conditions prevailed and no flight plan had been filed. The flight had departed Lakeland and was demonstrating a low altitude right pedal turn as part of the Sun n' Fun airshow. The pilot reported that the aircraft had a Revolutions per Minute (RPM) sensor that got engaged in the tailrotor drive shaft, eventually breaking the shaft. An FAA inspector looked at the failure and said the rotor RPM sensor started vibrating due to the failure of the #1 hanger bearing, resulting in failure of the tail rotor drive shaft, and a jammed tail rotor.