# NTSB CEN09LA384: Stinson 108-3, N6939M, Llano, TX, June 24, 2009 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 24, 2009, 11:30 local (16:30 UTC) - Place: Llano, TX - Coordinates: 30.783611, -98.661941 - Nearby events: https://openairdocs.org/map.md?lat=30.7836&lon=-98.6619&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report September 10, 2009 - Report: Approved by Office Director - NTSB office: Central Region - Parties: San Antonion FSDO - NTSB case key (mKey): 74126 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN09LA384 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/74126/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=74126 - Page: https://openairdocs.org/ntsb/CEN09LA384 ## Probable cause The pilot's inability to maintain aircraft control due to the failure of the left main landing gear wheel, which resulted in the separation of the wheel from the aircraft. ## 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 108-3, 2 cases](https://openairdocs.org/ntsb-findings/01023246/cases.md?model=9230408), [All aircraft, 48 cases](https://openairdocs.org/ntsb-findings/01023246/cases.md) - [Performance/control parameters](https://openairdocs.org/ntsb-findings/01062000): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Stinson 108-3, 2 cases](https://openairdocs.org/ntsb-findings/01062000/cases.md?model=9230408), [All aircraft, 1,269 cases](https://openairdocs.org/ntsb-findings/01062000/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: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) (defining event); cases with it: [Stinson 108-3, 2 cases](https://openairdocs.org/ntsb-events/338/sequence.md?model=9230408), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) - [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Stinson 108-3, 13 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=9230408), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis The student pilot was conducting his first solo flight. During the rollout after his third landing, the aircraft began to pull to the left. The pilot attempted to maintain directional control but the left main gear separated, causing the aircraft to nose over onto its back. The left main wheel and brake caliper were located several hundred feet behind the aircraft, along the rollout path. A mechanic who inspected the aircraft after the accident reported that the inner wheel half was broken around the brake disc mounting flange. The mechanic stated that there was no bluing from excessive heat or any signs that the bearings had failed. ## Factual narrative On June 24, 20094, approximately 1130 central daylight time, a Stinson 108-3, N6939M, registered to and operated by a student pilot, was substantially damaged when it nosed over on landing roll at Llano Municipal Airport (AQO), Llano, Texas. Visual meteorological conditions prevailed at the time of the accident. The instructional flight was being conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91 without a flight plan. The student pilot was not injured. The local flight originated from Llano approximately 1120. The student pilot was soloing for the first time. During the third landing rollout, the airplane began to pull to the left. The student pilot attempted to maintain directional control but the left main gear separated, causing the airplane to nose over onto its back. The left main wheel and brake caliper were located several hundred feet behind the airplane, along the rollout path. A mechanic who later inspected the airplane after the accident reported that the inner wheel half was broken around the brake disc mounting flange. The mechanic stated there was no bluing from excessive heat or any signs that the bearings had failed. ## Aircraft - Registration: [N6939M](https://openairdocs.org/aircraft/N6939M), registered now, S/N 108-4939, built 1950 (OpenAirDocs) - Reported make and model: STINSON 108-3 - Registry model: [Stinson 108-3](https://openairdocs.org/model/stinson-108-3) (registry code 9230408) (OpenAirDocs) - Registry engine: [Franklin 6A4165 series](https://openairdocs.org/engine/franklin-6a4165-series) (registry code 27025, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 108-4939 - Engines: Franklin 64A--165-B3 165 hp reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Standard, Normal - Departed: AQO, Llano, TX - Destination: AQO, Llano, TX - Airport: AQO, Llano Municipal, runway 13, 3,240 × 150 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Student pilot; age 36; injuries: none; student; medical: class 3, without waivers/limitations; seat: left; flight hours: 31 total, 31 in this make and model, 1 as pilot in command, 31 in the last 90 days, 31 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 93 °F, dew point 64 °F - Altimeter: 29.97 inHg - Observed at: AQO ## 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 20090624012339A](https://openairdocs.org/incident/20090624012339A), Jun 24, 2009: Univar 1083, Llano, TX, Substantial damage. (-23) On Wednesday, June 24, 2009 at approximately 11:10 am CST, the student pilot was conducting solo touch and goes at aqo lalano municipal airport, Llano,… ## Other investigations on N6939M (1) 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. - [NTSB NYC88LA090](https://openairdocs.org/ntsb/NYC88LA090), Feb 18, 1988: Stinson 108 (N6939M), Oswego, NY, substantial damage ## Docket (6 files) The files NTSB released with the investigation on July 30, 2009, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=74126. 8.8 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 547 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40316226&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Mechanic's Statement (item 2, .PDF, 7.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40316264&FileExtension=.PDF&FileName=Mechanic%27s%20Statement-Redacted.PDF - Weather Reports and Records (item 3, .PDF, 237 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40316230&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-Master.PDF - Photo 1. Overturned N6939M. (item 4, .PDF, 73 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40316262&FileExtension=.PDF&FileName=Photo%201.%20Overturned%20N6939M.-Master.PDF - Photo 2. Inner half of left main wheel Note fracture around brake disc mounting flange. (item 5, .PDF, 562 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40316259&FileExtension=.PDF&FileName=Photo%202.%20Inner%20half%20of%20left%20main%20wheel%20Note%20fracture%20around%20brake%20disc%20mounting%20flange.-Master.PDF - Photo 3. Undamaged bearing races. (item 6, .PDF, 351 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40316263&FileExtension=.PDF&FileName=Photo%203.%20Undamaged%20bearing%20races.-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.