NTSB Identification: WPR09FA464
Nonscheduled 14 CFR Part 135: Air Taxi & Commuter
Accident occurred Thursday, September 24, 2009 in Tucson, AZ
Probable Cause Approval Date: 06/17/2010
Aircraft: EUROCOPTER AS 350 B3, registration: N103LN
Injuries: 4 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The pilot was in the final phase of the landing approach. About 5 feet over the hospital landing pad, the helicopter started to yaw left in an uncommanded fashion. The pilot countered the yaw with right anti torque pedal, which had no effect. He then rapidly lowered the collective and the helicopter landed hard and came to rest facing the opposite direction. Inspection of the helicopter revealed buckled skin on the tail boom approximately 2 feet aft of where the tail boom attaches to the rear structure. Hospital surveillance video captured the landing and showed the helicopter approach the landing spot. The helicopter then yawed left and landed facing the direction it came from. The event spanned about 4 seconds from the beginning of the yaw to the landing. The pilot stated that the winds were out of the west at 2-3 knots. Winds reported at the nearest weather reporting facility (6 miles to the southeast) at the time were 350 degrees at 7 knots. Examination of the helicopter control system revealed no anomalies and all system components functioned appropriately when tested.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The loss of directional control for undetermined reasons.

Full narrative available

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