# NTSB ANC10LA081: Stinson 108-2, N9569K, Port Alsworth, AK, August 29, 2010 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 28, 2010, 18:35 local (Aug 29, 2010, 02:35 UTC) - Place: Port Alsworth, AK - Coordinates: 60.199886, -154.280685 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=60.1999&lon=-154.2807&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) - Highest injury: No injuries - Injuries: 4 uninjured - Status: Completed, report May 19, 2011 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA FSDO-03 - NTSB case key (mKey): 77153 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC10LA081 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/77153/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=77153 - Page: https://openairdocs.org/ntsb/ANC10LA081 ## Probable cause The overstress fracture and failure of a main landing gear wheel during landing, resulting in the right wing striking the ground. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: wheel/ski/float](https://openairdocs.org/ntsb-findings/01023246): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Stinson 108-2, 1 case](https://openairdocs.org/ntsb-findings/01023246/cases.md?model=9230406), [All aircraft, 48 cases](https://openairdocs.org/ntsb-findings/01023246/cases.md) - [Landing gear system: wheel/ski/float](https://openairdocs.org/ntsb-findings/01023246): Aircraft › Aircraft systems · Capability exceeded (probable cause); cases with it: [Stinson 108-2, 1 case](https://openairdocs.org/ntsb-findings/01023246/cases.md?model=9230406), [All aircraft, 48 cases](https://openairdocs.org/ntsb-findings/01023246/cases.md) - [Terrain: rough terrain](https://openairdocs.org/ntsb-findings/03021015): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Stinson 108-2, 1 case](https://openairdocs.org/ntsb-findings/03021015/cases.md?model=9230406), [All aircraft, 442 cases](https://openairdocs.org/ntsb-findings/03021015/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: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) (defining event); cases with it: [Stinson 108-2, 2 cases](https://openairdocs.org/ntsb-events/337/sequence.md?model=9230406), [All aircraft, 290 cases](https://openairdocs.org/ntsb-events/337/sequence.md) ## Analysis The pilot was on a personal cross-country flight and had landed at an off-airport site. While taxiing to park, the right wheel broke and the plane tipped on its right wing. The right wing, wing spar, and aileron were damaged when the wing struck the ground. He reported no mechanical problems with the airplane prior to the accident. A postaccident examination of the broken wheel showed the center of the wheel casting adjacent to the inner bearing race had fractured around its circumference, and the casting piece and bearing race had separated from the wheel, allowing the axle to pivot. An examination at the National Transportation Safety Board's materials laboratory revealed features indicative of overstress separation of the flange. No indications of fatigue, corrosion or other preexisting conditions were noted. ## Factual narrative On August 28, 2010, about 1835 Alaska daylight time, a Stinson 108-2 airplane, N9569K, sustained substantial damage during an off airport landing, about 48 miles west of Port Alsworth, Alaska. The airplane was being operated by the pilot as a visual flight rules personal cross-country flight under the provisions of 14 Code of Federal Regulations Part 91, when the accident occurred. The commercial pilot and the two passengers were not injured. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight departed Port Alsworth about 1730. In a written report to the National Transportation Safety Board (NTSB) dated September 6, the pilot reported that he was taking his sons on a camping trip. He reported that after scouting a ridge west of Port Alsworth, he decided to land since it was a familiar tundra landing area that he had used in the past. He said he flew over the landing area three times to gauge wind conditions, and to be sure there were no new obstacles to be avoided in the landing area. After touching down and braking almost to a stop, he said he was taxiing into the area where he planned to park, when the right wheel broke, and the plane tipped on its right wing. He said the right wing, wing spar, and aileron were damaged when the wing struck the ground. On September 2, the NTSB investigator-in-charge (IIC) examined the broken wheel. The wheel had been mounted with 35 inch Alaskan Bush Wheels. The center of the wheel casting adjacent to the inner bearing race had fractured around its circumference, and the casting piece and bearing race had separated from the wheel, allowing the axle to pivot. On February 16, 2011, an examination of the fractured wheel was completed at the National Transportation Safety Board's materials laboratory. The investigation revealed features indicative of overstress separation of the flange. No indications of fatigue, corrosion or other preexisting conditions were noted. ## Aircraft - Registration: [N9569K](https://openairdocs.org/aircraft/N9569K), registered now, S/N 108-2569, built 1947 (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: [Continental IO-360 series](https://openairdocs.org/engine/continental-io-360-series) (registry code 17025, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 108-2569 - Airframe hours: 3106 - Engines: CONT MOTOR IO-360 SER 210 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Glen Alsworth Jr - Registered owner: Moving Up 2 Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 3, 2009 - Departed: AK51, Port Alsworth, AK - Destination: AK51, Port Alsworth, AK ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 33; injuries: none; commercial; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review June 24, 2010; seat: left; flight hours: 4,725 total, 85 in this make and model, 4,684 as pilot in command, 253 in the last 90 days, 86 in the last 30 days, 7 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 230° at 8 knots - Visibility: 20 statute miles - Lowest ceiling: 3,000 ft broken - Temperature: 52 °F, dew point 52 °F - Altimeter: 29.86 inHg - Observed at: PALJ, 48 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 20100828054259A](https://openairdocs.org/incident/20100828054259A), Aug 28, 2010: Stinson 108-2, Port Alsworth, AK, Substantial damage. After landing while taxiing to parking the right main landing gear wheel seperated from the aircraft causing the right wing to contact the ground.… ## Docket (3 files) The files NTSB released with the investigation on March 11, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=77153. 1.7 MB in all. - Materials Laboratory 15 - Factual Report 11-016 (item 1, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40343697&FileExtension=.PDF&FileName=Materials%20Laboratory%2015%20-%20Factual%20Report%2011-016-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 586 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40344887&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Release of Aircraft Wreckage (item 3, .PDF, 66 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40344888&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage-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.