TOMAHAWK, WI, USA
N774HB
Sorrell SNS-7
During the aerobatic routine, two snap rolls to the right were accomplished. At the end of the second roll, the pilot experienced a sharp roll to the left. After leveling out the pilot complained of no elevator control. Altitude could not be maintained and, with the engine at full power, the airplane impacted into trees. The postaccident examination shows no mechanical defects that could not be attributed to the loss of control. Engine and flight control continuity checks normal. Evidence shows engine was running at a high power setting consistent with the pilot's account.
On July 27, 1997, at 1320 central daylight time (cdt), a Sorrell SNS-7, N774HB, piloted by a commercially certified pilot, was destroyed during a collision with the ground and subsequent fire while demonstrating aerobatic maneuvers at an airshow. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 demonstration flight was not operating on a flight plan. The pilot reported no injuries. The flight departed Tomahawk, Wisconsin, exact time unknown. According to the pilot's written statement while performing aerobatics for an airshow, the pilot was performing two snap rolls, from which the airplane recovered normally but was still in a 45-degree nose down attitude and accelerating. He said the airplane did not responded to forward or rearward stick inputs. The airplane rolled to the left and was losing altitude. The airplane impacted a tree with the right wing. The pilot continued with full power and wings level as he approached a tree line. After numerous collisions with the trees, the airplane came to rest in a heavy wooded area. An aerobatic expert commented on a video of the airshow performance. From the videotape he said it looked like the airplane was losing quite a bit of energy during an attempted double snap roll to the right on a down line, and recovery was started after one and one half turns of the roll. The airplane was vertical as it stopped rolling, and the nose pitched up but the airplane continued to descend and started a left turn. This led him to believe that the airplane didn't recover from the stalled condition during the snap maneuver and the torque and slipstream effects from the high power setting were causing the left turn. A Federal Aviation Administration (FAA) Inspector represented the NTSB during the on-scene investigation. The Inspector's examination of the wreckage revealed no mechanical defects that could not be attributed to the loss of control. Engine and flight controls continuity checks were normal. Evidence shows the engine was running at a high power setting consistent with the pilot's account.
The pilot encountered a tailplane stall. The factors involved were the pilot conducted a low altitude flight maneuver and encountered engine torque effect.
Source: NTSB Aviation Accident Database
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