Aviation Accident Summaries

Aviation Accident Summary DEN05CA085

Wallsburg, UT, USA

Aircraft #1

N993RW

Robinson R22 Beta II

Analysis

According to the flight instructor, they were practicing confined area approach procedures. During the approach the rpm began to decay and the flight instructor took control of the helicopter and initiated a low rotor rpm recovery. Normal rotor rpm returned, but a significant loss of altitude had occurred so the flight instructor elected to land. After landing the instructor stated that he initiated a vertical climb to "establish power capability" and then descended back down to "start their climb." As a positive climb rate was established, the flight instructor attempted to gain forward speed to help the climb rate. The helicopter began sinking so he maneuvered down to the ground at which time the right skid of the helicopter "sunk into the mud," and the helicopter rolled over, causing substantial damage. The accident site elevation was estimated to be 8,000 feet msl. The calculated density altitude varied between 8,916 feet and 9,732 feet.

Factual Information

On June 7, 2005, approximately 1500 mountain daylight time, a Robinson R22 Beta II, N993RW, operated by Silver State Helicopters LLC., was substantially damaged when it impacted terrain 10 miles southeast of Wallsburg, Utah. Visual meteorological conditions prevailed at the time of the accident. The local instructional flight was being conducted under the provisions of Title 14 CFR Part 91 without a flight plan. The commercial certificated flight instructor and commercial certificated pilot receiving instruction (hereafter referred to as the student) reported no injuries. The local flight departed Provo, Utah, approximately 1430. According to the accident report submitted by the flight instructor, they were practicing confined area approach procedures. In a separate statement s the student, stated that during the approach he "started to pull up on the collective," at which time the rpm began to decay. The flight instructor stated he took control of the helicopter and initiated a low rotor rpm recovery. Normal rotor rpm returned, but a significant loss of altitude had occurred so the flight instructor elected to land. The instructor stated that, after landing, he initiated a vertical climb to "establish power capability" and then descended back down to "start their climb." As a positive climb rate was established, the flight instructor attempted to gain forward speed to help the climb rate. The helicopter began sinking so he maneuvered down to the ground at which time the right skid of the helicopter "sunk into the mud," and the helicopter rolled over. Both the main rotor and the tail rotor blades were bent, the left skid was bent under the helicopter, and the fuselage was wrinkled. An examination of the helicopter's systems revealed no anomalies. The accident site elevation was estimated to be 8,000 feet msl. The calculated density altitude varied between 8,916 feet and 9,732 feet.

Probable Cause and Findings

the flight instructor's inadequate in-flight planning and decision making and failure to maintain aircraft control. Contributing factor's include the flight instructor's inadequate supervision of the flight, the student pilot's failure to maintain rotor rpm, the high density altitude, and the muddy terrain.

 

Source: NTSB Aviation Accident Database

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