On May 30, 2002, a Bell 206 (registration N820H) was involved in an aviation accident near Columbus, OH. Investigators recorded the probable cause as: The flight instructor's delay in applying remedial action. A factor in the accident was the pilot allowing the rotor rpm to become too low during the deceleration and touchdown phase of the autorotation. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an instructional autorotation, the pilot overshot the intended touchdown point, resulting in a hard landing that damaged the tailboom and main transmission mounts.
Accident Sequence
During an instructional flight, the flight instructor reduced the throttle to idle. The pilot then lowered the collective and initiated an autorotation. Initially, the pilot was uncertain about reaching the intended touchdown point and sought to increase airspeed. The instructor directed the pilot to slow the helicopter to 50 knots. The pilot applied aft cyclic, reducing airspeed to approximately 40 knots. Convinced that maintaining 50 knots would prevent reaching the intended point, the pilot lowered the nose. As airspeed increased, the pilot realized he would overshoot the touchdown point. To lose altitude, the pilot executed a left turn followed by a right turn. The pilot then initiated a flare, applied initial collective, and subsequently used additional collective to cushion the landing.
Damage
During the landing sequence, rotor RPM decayed. The helicopter touched down hard on the aft part of the skids and then rocked forward. The event resulted in substantial damage to the tailboom and main transmission mounts.