NTSB Identification: LAX98LA304.
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Accident occurred Thursday, September 24, 1998 in MESA, AZ
Probable Cause Approval Date: 02/22/2001
Aircraft: Boeing 369E, registration: N685F
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The instructor pilot and his student were practicing autorotations to a turf area, which was wet and soft. The instructor pilot demonstrated a 180-degree autorotation, which he said appeared to finish with a normal deceleration flare and touchdown. After touchdown the instructor pilot stated he heard a loud rattling sound coming from the tailboom. The aircraft was examined and found that during the autorotation, the tailrotor blades had hit the ground causing damage to the tail rotor blades and tailboom, and it had severed the tail rotor driveshaft. Ground witnesses said the helicopter hit the ground harder than normal.

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

A hard landing caused by the pilot's improper flare during a simulated autorotatative landing. A factor in the accident was the soft wet sod landing area.

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