Aviation Accident Summaries

Aviation Accident Summary LAX01LA292

Mesa, AZ, USA

Aircraft #1

N995PM

Bell 206-L4

Analysis

During a practice autorotation, the helicopter landed hard bending the tail boom. An examination of the helicopter indicated the damage resulted from the hard landing. The tail boom had ripped out at the aft bulkhead, and the landing skids were bent upward at the aft end. The nose of the helicopter was also damaged when the helicopter rocked forward after the hard landing. The helicopter then stopped upright on the skids with no damage to the main rotor blades. The pilot stated that he was doing a practice autorotation landing when the accident occurred. During the last landing, the helicopter "fell through" much faster than anticipated. The pilot stated that no mechanical anomalies were experienced prior to or after the accident. The temperature at the time of the accident was 100 degrees Fahrenheit. The pilot stated that in the future he will allow a higher margin for autorotation power recovery in hot conditions.

Factual Information

On August 28, 2001, at 1030 hours mountain standard time, a Bell 206-L4, N995PM, was substantially damaged when the tail boom was bent after contacting the ground during a practice autorotation landing at Falcon Field, Mesa, Arizona. The airline transport pilot and one passenger were not injured. Visual meteorological conditions prevailed for the flight operated by Pacific Marine Leasing under 14 CFR Part 91. The helicopter departed Falcon Field about 1030 for the local flight, and no flight plan was filed. The pilot was interviewed by an investigator from the National Transportation Safety Board shortly after the accident. He stated that he was doing a practice autorotation landing when the accident occurred. During the last landing, the helicopter "fell through" much faster than anticipated. In the resulting steep flare, the tail boom contacted the ground and was bent. The helicopter then touched down on the skids relatively softly and slid to a stop. The pilot accomplished a normal engine shutdown procedure and exited the helicopter. The temperature at the time of the accident was 100 degrees Fahrenheit. The pilot stated that no mechanical anomalies were experienced prior to or after the accident. The pilot stated that in the future he will allow a higher margin for autorotation power recovery in hot conditions. According to an inspector from the Federal Aviation Administration, Scottsdale Flight Standards District Office, the damage was the result of the hard landing. According to the inspector, who examined the wreckage, the tail boom was broken prior to striking the ground due to a hard landing. He stated that the tail boom had ripped out at the aft bulkhead, and the landing skids were bent upward at the aft end. There was also damage to the nose of the helicopter. According to the inspector, the helicopter hit the ground hard enough to separate the tail boom from the fuselage and bend the skids, then rocked forward, damaging the nose. The helicopter then stopped upright on the skids. The main rotor blades were not damaged.

Probable Cause and Findings

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.

 

Source: NTSB Aviation Accident Database

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