# NTSB CEN13CA187: Champion 7GCAA, N9691S, Oshkosh, WI, February 2, 2013 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: February 2, 2013, 15:30 local (21:30 UTC) - Place: Oshkosh, WI - Coordinates: 43.984443, -88.556663 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.9844&lon=-88.5567&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Defining event: [Taxi-from runway: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report July 29, 2013 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA FSDO Milwaukee - NTSB case key (mKey): 86371 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN13CA187 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/86371/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=86371 - Page: https://openairdocs.org/ntsb/CEN13CA187 ## Probable cause Fatigue cracking and failure of the left wheel strut mount resulting in collapse of the left main landing gear during taxi. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: main landing gear attach sec](https://openairdocs.org/ntsb-findings/01023211): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Champion 7GCAA, 1 case](https://openairdocs.org/ntsb-findings/01023211/cases.md?model=21101N8), [All aircraft, 66 cases](https://openairdocs.org/ntsb-findings/01023211/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Taxi-from runway: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Champion 7GCAA, 1 case](https://openairdocs.org/ntsb-events/094/sequence.md?model=21101N8), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis After performing three touch-and-go landings on a frozen lake, the pilot set up for a full stop landing on the plowed surface of the frozen lake. After a smooth landing, and while taxiing to park, the left wheel strut collapsed. The airplane tipped over onto its left side, resulting in substantial damage to the left wing spar. Examination of the airplane after the accident revealed evidence of fatigue cracking on the failed portion of the left wheel strut mount. The airplane had been flown about 50-75 hours after its last annual inspection with no problems noted by the owner. The pilot stated that he lands on frozen lakes frequently and that the collapse of the landing gear was unexpected. ## Factual narrative After performing three touch-and-go landings on a frozen lake, the pilot set up for a full stop landing on the plowed surface of the frozen lake. After a smooth landing, and while taxiing to park, the left wheel strut collapsed. The airplane tipped over onto its left side, resulting in substantial damage to the left wing spar. Examination of the airplane after the accident revealed evidence of fatigue cracking on the failed portion of the left wheel strut mount. The airplane had been flown about 50-75 hours after its last annual inspection with no problems noted by the owner. The pilot stated that he lands on frozen lakes frequently and that the collapse of the landing gear was unexpected. ## Aircraft - Registration: [N9691S](https://openairdocs.org/deregistered/N9691S-2014-08-21), registration cancelled 2014-08-21, S/N 115, built 1966 (OpenAirDocs) - Reported make and model: CHAMPION 7GCAA - Registry model: [Champion 7GCAA](https://openairdocs.org/model/champion-7gcaa) (registry code 21101N8) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 115 - Airframe hours: 6542 - Engines: LYCOMING 0-320 SERIES 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Keith Mustain - Registered owner: Keith Mustain - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 8, 2012, 60 hours before - Departed: OSH, Oshkosh, WI - Destination: OSH, Oshkosh, WI - Flight plan: VFR - Airport: OSH, Oshkosh ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 55; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review May 20, 2011; seat: front; flight hours: 394 total, 334 in this make and model, 394 as pilot in command, 5 in the last 90 days, 2 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 280° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Observed at: OSH, 7 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 20130202002209A](https://openairdocs.org/incident/20130202002209A), Feb 2, 2013: Champion 7GCAA, Oshkosh, WI, Substantial damage. The pilot stated that he had performed several takeoffs and landings on ice covered lake winnebago. While taxiing at approximately 15 mph after the last… ## Docket (7 files) The files NTSB released with the investigation on July 19, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=86371. 13.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40396210&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Record of Telephone Conversation with Pilot (item 2, .PDF, 38 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40396211&FileExtension=.PDF&FileName=Record%20of%20Telephone%20Conversation%20with%20Pilot-Master.PDF - Record of Telephone Conversation with FSDO Inspector (item 3, .PDF, 39 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40396212&FileExtension=.PDF&FileName=Record%20of%20Telephone%20Conversation%20with%20FSDO%20Inspector-Master.PDF - Photo 1 Landing Area with Airplane in Backround (item 4, .PDF, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40396213&FileExtension=.PDF&FileName=Photo%201%20Landing%20Area%20with%20Airplane%20in%20Backround-Master.PDF - Photo 2 Airplane Showing Left Landing Gear Collapse (item 5, .PDF, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40396214&FileExtension=.PDF&FileName=Photo%202%20Airplane%20Showing%20Left%20Landing%20Gear%20Collapse-Master.PDF - Photo 3 Failed Left Wheel Strut Mount (item 6, .PDF, 2.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40396215&FileExtension=.PDF&FileName=Photo%203%20Failed%20Left%20Wheel%20Strut%20Mount-Master.PDF - Photo 4 Closeup of Failed Left Wheel Strut Mount (item 7, .PDF, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40396216&FileExtension=.PDF&FileName=Photo%204%20Closeup%20of%20Failed%20Left%20Wheel%20Strut%20Mount-Master.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.