# NTSB CEN25LA287: Aerotek Pitts S-2A, N83PS, New Holstein, WI, July 26, 2025 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 4 · Limited · Final report - Date: July 26, 2025, 10:33 local (15:33 UTC) - Place: New Holstein, WI - Coordinates: 43.943422, -88.112606 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.9434&lon=-88.1126&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report October 30, 2025 - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Central Region - Parties: FAA - NTSB case key (mKey): 200634 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN25LA287 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/200634/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=200634 - Page: https://openairdocs.org/ntsb/CEN25LA287 ## Probable cause The pilot’s loss of direction control during landing due to an unapproved tailwheel assembly and tail spring that resulted in a tailwheel shimmy and a subsequent ground loop. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: nose/tail landing gear](https://openairdocs.org/ntsb-findings/01023220): Aircraft › Aircraft systems · Malfunction (probable cause); cases with it: [Aerotek PITTS S-2A, 1 case](https://openairdocs.org/ntsb-findings/01023220/cases.md?model=0110201), [All aircraft, 185 cases](https://openairdocs.org/ntsb-findings/01023220/cases.md) - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Aerotek PITTS S-2A, 3 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=0110201), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) - [Landing gear system: nose/tail landing gear](https://openairdocs.org/ntsb-findings/01023220): Aircraft › Aircraft systems · Incorrect service/maintenance (probable cause); cases with it: [Aerotek PITTS S-2A, 1 case](https://openairdocs.org/ntsb-findings/01023220/cases.md?model=0110201), [All aircraft, 185 cases](https://openairdocs.org/ntsb-findings/01023220/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-landing roll: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Aerotek PITTS S-2A, 1 case](https://openairdocs.org/ntsb-events/330/sequence.md?model=0110201), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230); cases with it: [Aerotek PITTS S-2A, 3 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=0110201), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Landing-landing roll: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [Aerotek PITTS S-2A, 2 cases](https://openairdocs.org/ntsb-events/300/sequence.md?model=0110201), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) ## Analysis The pilot reported that during landing on the asphalt runway, with a passenger in the front seat, the airplane had a significant tailwheel shimmy. The pilot attempted to stop the shimmy by lifting the tailwheel off the runway as the airplane continued to decelerate. As the speed decreased, the tailwheel settled back onto the runway and shimmied again, but directional control was maintained. However, the shimmy eventually became more adverse, and the pilot was unable to maintain directional control of the airplane. The airplane ground looped to the left, came to rest adjacent to the runway, and sustained substantial damage to the right wing and empennage. Postaccident examination revealed that an unapproved tailwheel assembly and tail spring were installed. The tailwheel created a negative castor angle and reduced trail, which was exacerbated by the additional weight of the rear occupant, and resulted in the tailwheel shimmy during landing. ## Aircraft - Registration: [N83PS](https://openairdocs.org/aircraft/N83PS), registered now, S/N 2143, built 1977 (OpenAirDocs) - Reported make and model: AEROTEK PITTS S-2A - Registry model: [Aerotek PITTS S-2A](https://openairdocs.org/model/aerotek-pitts-s-2a) (registry code 0110201) (OpenAirDocs) - Registry engine: [Lycoming AEIO-360 series](https://openairdocs.org/engine/lycoming-aeio-360-series) (registry code 41522, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 2143 - Year built: 1977 - Airframe hours: 550.44 - Engines: LYCOMING AEIO-360-A1A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Aerobatic - Last inspection: Annual, May 1, 2025 - Departed: Kosh, Oshkosh, WI - Destination: 8D1, New Holstein, WI - Airport: 8D1, New Holstein Municipal Airport, runway 14/32, 3,600 × 75 ft, asphalt - Equipment: Stall warning system, ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; injuries: none; airline transport; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 3, without waivers/limitations; last flight review April 11, 2025; seat: rear; restraint: 5-point; flight hours: 3,308 total, 30.6 in this make and model, 3,165 as pilot in command, 42.8 in the last 90 days, 21.1 in the last 30 days, 0.5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 77 °F, dew point 68 °F - Altimeter: 29.98 inHg - Observed at: KSBM, 15 nm away - METAR: KSBM 261453Z AUTO 00000KT 10SM CLR 25/20 A2998 RMK AO2 SLP149 T02500200 55002 ## 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 20250726013969A](https://openairdocs.org/incident/20250726013969A), Jul 26, 2025: Aerotek PITTS S-2A, New Holstein, WI, Substantial damage. On July 26, 2025, at 1533Z (1033 CDT), an Aerotek pitts S-2A aircraft, piloted from the rear seat with a passenger in the front, diverted after takeoff from… ## Docket (4 files) The files NTSB released with the investigation on November 4, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=200634. 2.6 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 369 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19371714&FileExtension=pdf&FileName=6120%20-%20Pilot_Redacted-Rel.pdf - FAA inspector's statement (item 2, PDF, 4 pages, 970 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19370991&FileExtension=pdf&FileName=FAA%20email%20report_Redacted-Rel.pdf - Photos (item 3, PDF, 5 pages, 4 photos, 953 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19372659&FileExtension=pdf&FileName=Docket%20photos-Rel.pdf - Aviation products tailwheel information (item 4, PDF, 2 pages, 326 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19423913&FileExtension=pdf&FileName=Aviation%20Products%20tailwheel%20and%20tailspring%20information-Rel.pdf 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.