Norfolk, VA, USA
N152SP
Robinson R-22
The commercial pilot/mechanic took off after performing maintenance on the helicopter. He performed four 90-degree pedal turns, during which he experienced no anomalies. He then climbed the helicopter to 500 feet and started to enter a left turn while lowering the collective. He lowered the nose to gain airspeed, and then entered a simulated autorotation. As the pilot pulled in collective, the helicopter continued to descend, and the collective appeared to be ineffective. With the collective in the full up position, the helicopter continued to sink, and impacted the ground. The helicopter bounced, then rolled over into a ditch. Examination of the helicopter by a Federal Aviation Administration (FAA) inspector revealed that the left collective torque tube was fractured at its welded attachment point to the base. Examination of the weld revealed rust on the fracture surface; however, further examination of the fracture surfaces revealed an overstress fracture. Additionally, an examination of the left collective torque tube revealed it interfered with the left seat and could not be extended to the full up position; however, no previous anomalies were reported with the collective movement prior to the accident flight. No mechanical deficiencies were observed with the belts, and no belt slippage was observed.
On July 9, 2004, at 1515 eastern daylight time, a Robinson R-22, N152SP, was substantially damaged when it impacted the ground during an autorotation at the Hampton Roads Executive Airport (PVG), Norfolk, Virginia. The certificated commercial pilot received serious injuries, and the private pilot/owner received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the maintenance test flight which was conducted under 14 CFR Part 91. According to the commercial pilot, he had performed maintenance on the helicopter which included replacing the drive belts, the alternator belt, and balancing the fan wheel. The pilot then test flew the helicopter, during which, he "loaded" the tail rotor, and thought he felt "some slippage." He landed the helicopter and asked another mechanic to adjust the clutch disengage stop. The following day, the pilot flew the helicopter with its owner to ensure that the owner was satisfied with the work. The flight departed to the west and the pilot performed four, 90-degree pedal turns, during which, he experienced no anomalies. He then climbed the helicopter to 500 feet and started to enter a left turn while lowering the collective. He lowered the nose to gain airspeed, then entered a simulated autorotation. As the pilot pulled in collective, the helicopter continued to descend, and the collective appeared to be ineffective. With the collective in the full up position, the helicopter continued to sink, and impacted the ground. The helicopter bounced, then rolled over into a ditch. Examination of the helicopter by a Federal Aviation Administration (FAA) inspector revealed that the left collective torque tube was fractured at its welded attachment point to the base. Examination of the weld revealed rust on the fracture surface. In addition, examination of the left collective torque tube revealed that it interfered with the left seat and could not be extended to the full position; however, no previous anomalies had been reported with the collective movement. No mechanical deficiencies were observed with the belts, and no belt slippage was observed. The collective fracture surfaces were further examined by Robinson Helicopter Company personnel, and at the Safety Board Metallurgical Laboratory. The examinations revealed an overstress fracture, with no evidence of fatigue.
The pilot's failure to complete an autorotation due to the restrictive movement of the collective control.
Source: NTSB Aviation Accident Database
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