# NTSB SEA02LA074: Stinson 108-2, N959D, Helena, MT, April 20, 2002 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 20, 2002, 12:30 local (18:30 UTC) - Place: Helena, MT - Coordinates: 47.980094, -110.799949 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.9801&lon=-110.7999&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed, report February 25, 2003 - Report: Approved by Office Director - Parties: FAA - NTSB case key (mKey): 54569 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA02LA074 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/54569/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=54569 - Page: https://openairdocs.org/ntsb/SEA02LA074 ## Probable cause Fracture of the left main wheel assembly during the takeoff roll. Factors include the use of a wheel assembly not approved for the accident airplane, and the use of an oversized tire. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, takeoff - roll/run - landing gear,wheel - fractured (cause) - landing gear,wheel - unapproved (contributing factor) - landing gear,tire - other (contributing factor) - Loss of control - on ground/water, takeoff - roll/run - aircraft control - not successful, pilot in command - Main gear collapsed, takeoff - roll/run ## Analysis The pilot reported that shortly after applying power for takeoff, the airplane started to track left of runway centerline. During his attempts to correct the situation, the airplane's right main wheel assembly and right landing gear strut collapsed. Post-accident examination of the wheel assembly and tire installed on the accident airplane revealed that the outboard wheel subassembly fractured in multiple locations along the bead seat ring. Multiple fractures were observed in the inboard wheel subassembly, and the brake disc had partially separated from the wheel. The Type Certificate Data Sheet for the airplane lists multiple approved wheel-brake assemblies for the aircraft. The wheel assembly found on the airplane is not listed as one of the approved installations, and the wheel assembly was not approved for use with tires larger than size 7.00-6. The accident airplane was equipped with 8.00-6 size tires. The airplane's last inspection, an annual inspection, was performed on March 7, 2002. ## Factual narrative On April 20, 2002, about 1230 mountain daylight time, a tail-wheel equipped Stinson 108-2, N959D, experienced a right main gear collapse while on takeoff roll at the Helena Regional Airport, Helena, Montana. The commercial pilot and the two passengers aboard the airplane were not injured, however, the airplane sustained substantial damage. The Title 14, CFR Part 91personal flight was being operated in visual meteorological conditions, and no flight plan was filed. The pilot reported that he was departing from runway 34, and that shortly after applying power for takeoff, the airplane started to track left of runway centerline. During his attempts to correct the situation, the airplanes right main wheel assembly and right landing gear strut collapsed, resulting in substantial damage to the firewall and right aileron. Post-accident examination of the Cleveland wheel assembly (model 40-113X), and tire (McCreary size 8.00-6), installed on the accident airplane, revealed that the outboard wheel subassembly fractured in multiple locations along the bead seat ring. Multiple fractures were observed in the inboard wheel subassembly, and the brake disc had partially separated from the wheel. The Type Certificate Data Sheet (TCDS), number A-767, for the Univair (Stinson) 108-2, lists multiple approved wheel-brake assemblies for the airplane. The Cleveland 40-113X wheel assembly is not listed as one of the approved installations. A representative from Parker Hannifin Corporation, Aircraft Wheel and Brake Division (Cleveland), also reported that the accident wheel assembly was approved for use with 6.00-6 and 7.00-6 sized tires, but not with 8.00-6 sized tires. Reviews of the maintenance records for the accident airplane indicate that the wheel assembly was installed on August 1, 1991. The records also indicate that the airplane's last inspection, an annual inspection, was performed on March 7, 2002. ## Aircraft - Registration: [N959D](https://openairdocs.org/aircraft/N959D), registered now, S/N 108-2959, built 1949 (OpenAirDocs) - Reported make and model: Stinson 108-2 - Registry model: [Stinson 108-2](https://openairdocs.org/model/stinson-108-2) (registry code 9230406) (OpenAirDocs) - Registry engine: [Franklin 6A4165 series](https://openairdocs.org/engine/franklin-6a4165-series) (registry code 27025, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 2959 - Airframe hours: 1835 - Engines: Lycoming O-360 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Robert J. Benjamin - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 7, 2002, 14 hours before - Departed: HLN, Helena, MT - Destination: HLN, Helena, MT - Airport: HLN, Helena Regional, runway 34, 2,980 × 75 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 57; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; last flight review March 13, 2002; seat: left; flight hours: 561 total, 14 in this make and model, 561 as pilot in command, 14 in the last 90 days, 14 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 48 °F, dew point 14 °F - Altimeter: 29.95 inHg - Observed at: KHLN ## 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 20020420010439A](https://openairdocs.org/incident/20020420010439A), Apr 20, 2002: Univar 1082, Helena, MT, No damage. (-23) The pilot stated that on takeoff roll the aircraft got "squirrely" and he over-corrected, and in the process, the right main landing gear collapsed. He… ## Docket (3 files) The files NTSB released with the investigation on November 18, 2002, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=54569. 364 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 295 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40432513&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Report from Manufacture (item 2, .PDF, 38 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40432514&FileExtension=.PDF&FileName=Report%20from%20Manufacture-Redacted.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 3, .PDF, 31 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40432515&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Redacted.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.