# NTSB CHI97LA225: Sorrell SNS-7, N774HB, Tomahawk, WI, July 27, 1997 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 27, 1997, 13:20 local (18:20 UTC) - Place: Tomahawk, WI - Coordinates: 45.469413, -89.720024 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=45.4694&lon=-89.7200&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report May 4, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 10641 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI97LA225 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/10641/pdf - Page: https://openairdocs.org/ntsb/CHI97LA225 ## Probable cause The pilot encountered a tailplane stall. The factors involved were the pilot conducted a low altitude flight maneuver and encountered engine torque effect. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Abrupt maneuver, maneuvering - aerobatics - performed, pilot in command - Loss of control - in flight, maneuvering - low altitude flight/maneuver - low, pilot in command (contributing factor) - tailplane stall - encountered, pilot in command (cause) - torque/p-factor - encountered, pilot in command (contributing factor) - In flight collision with terrain/water, descent - uncontrolled - object - tree(s) ## Analysis 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. ## Factual narrative 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. ## Aircraft - Registration: [N774HB](https://openairdocs.org/deregistered/N774HB-1998-12-08), registration cancelled 1998-12-08, S/N 204 (OpenAirDocs) - Reported make and model: Sorrell SNS-7 - Registry model: [Sorrell SNS-7](https://openairdocs.org/model/sorrell-sns-7) (registry code 0565323) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 204 - Engines: Lycoming AEIO-360-A1D 230 horsepower reciprocating - Damage: Destroyed - Flight: Part 91 - Registered owner: Gerald J. Haggerty - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, May 15, 1997, 19 hours before - Departed: T08 - Destination: T08 - Airport: WI46, Tomahawk Regional, runway 27, 4,000 × 75 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 2,531 total, 2,500 as pilot in command, 35 in the last 90 days, 22 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: 10,000 ft broken - Temperature: 82 °F - Altimeter: 29.00 inHg - Observed at: RHI, 16 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19970727019789A](https://openairdocs.org/incident/19970727019789A), Jul 27, 1997: Amtrhy SNS7, Tomahawk, WI, Destroyed. Aircraft performing airshow, coming out of a descending snap roll, unable to get full elevator response, crashed. (-23) on July 27, 1997, at 271820Z, a sorrell… From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.