On August 28, 2001, a Bell 206-L4 (registration N995PM) was involved in an aviation accident near Mesa, AZ. Investigators recorded the probable cause as: The pilot's improper autorotation in that he failed to attain the proper descent rate resulting in a hard landing and subsequent airframe damage. A factor was the high temperature. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter sustained damage during a practice autorotation landing when it fell through faster than anticipated. The pilot attributed the hard landing to hot conditions.
Damage Description
Following the hard landing, an examination of the helicopter revealed that the tail boom had separated at the aft bulkhead. The landing skids were bent upward at the aft ends. The nose section was also damaged as the helicopter rocked forward after the initial impact. Despite the severity of the hard landing, the helicopter remained upright on its skids, and the main rotor blades were not damaged.
Pilot Account
The pilot stated that the accident occurred during a practice autorotation landing. He noted that the helicopter "fell through" at a rate considerably faster than anticipated during the final landing phase. The pilot confirmed that no mechanical issues were present before or after the event.
Environmental Conditions
The temperature at the time of the accident was recorded at 100 degrees Fahrenheit. The pilot indicated that in future autorotation practices, he would incorporate a greater margin for power recovery in hot conditions.