# NTSB WPR21LA064: Stinson 108-3, N6855M, El Monte, CA, November 3, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: November 3, 2020, 12:35 local (20:35 UTC) - Place: El Monte, CA - Coordinates: 34.086009, -118.03484 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.0860&lon=-118.0348&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: FAA - NTSB case key (mKey): 102360 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21LA064 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102360/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102360 - Page: https://openairdocs.org/ntsb/WPR21LA064 ## Probable cause A loss of directional control during the landing roll due to an undetermined failure of the tailwheel assembly. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [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: [Stinson 108-3, 11 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=9230408), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Stinson 108-3, 3 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=9230408), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Stinson 108-3, 12 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=9230408), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) ## Analysis During an instructional flight in the tailwheel-equipped airplane, the airplane veered left. Despite the instructor’s application of corrective control inputs, the airplane did not respond as expected, ultimately resulting in a ground loop and substantial damage to the left wing. Postaccident examination revealed that both of the airplane’s tailwheel steering springs and tension chains were missing. The springs were found on the runway following the accident, separated from each other by about 1,700 ft. Neither of the chains were located. The manufacturer’s instructions called for the spring to connect directly to the tailwheel yoke, and the chain to connect to the steering arm with a connector clip. Evidence suggests that the spring was instead incorrectly connected directly to the steering arm. This reverse installation, while not in compliance with the maintenance instructions, did not appear to functionally affect the operation of the steering system, and therefore without examination of the missing chains or further examination of the tailwheel assembly, the significance of this finding could not be determined. ## Factual narrative On November 03, 2020, about 1235 Pacific daylight time, a Stinson 108-3, N6855M, sustained substantial damage when it was involved in an accident in El Monte, California. The flight instructor and the pilot receiving instruction were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. According to the flight instructor, the purpose of the flight was to provide tailwheel instruction to the private pilot. The pilot receiving instruction performed three full-stop takeoffs and landings from runway 19. During the landing roll following the fourth landing, the airplane began to veer to the left. The instructor assumed the flight controls and applied rudder, but the airplane did not respond. The instructor then applied right brake and the airplane began to turn to the right, but his subsequent application of left rudder produced no response. The airplane continued to turn to the right, and the left wing impacted the ground. The airplane came to rest facing the opposite direction and sustained substantial damage to the left wing and aileron. The airplane was equipped with a Scott 3000 series tailwheel assembly. The design incorporated a swiveling steering arm, that was connected to and controlled by the tailwheel steering yoke through a spring and a tension chain on both the left and right sides. The manufacturer’s instructions called for the spring to be connected directly to the tailwheel yoke, and the chain to be connected to the steering arm with a connector clip. Postaccident examination of the airplane revealed that both of the steering springs and chains had separated from both the tailwheel steering yoke and steering arm assembly and that the tension chain connector clips were connected to the tailwheel steering yoke rather than the steering arm. Both steering springs were located on the runway after the accident. One spring was recovered near the runway 19 centerline about 230 ft beyond the runway threshold, and the second was recovered from the safety area on the left side of the runway about 1,900 ft beyond the threshold. The left and right tension chains were not located. According to the airplane’s maintenance logbooks, the most recent annual inspection was completed 7 flight hours prior to the accident. ## Aircraft - Registration: [N6855M](https://openairdocs.org/deregistered/N6855M-2023-01-14), registration cancelled 2023-01-14, S/N 108-4855, built 1949 (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: 32666 - Year built: 1949 - Airframe hours: 3427 - Engines: Franklin 6A4-165-B3 165 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Mondo Beyondo Thrill Squadron - Registered owner: Mondo Beyondo Thrill Squadron - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 4, 2020 - Destination: Same as departure - Airport: EMT, San Gabriel Valley Airport, runway 19, 3,995 × 75 ft, asphalt - Equipment: ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 57; injuries: none; flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review January 10, 2020; seat: right; restraint: 4-point; flight hours: 5,556.1 total, 23.3 in this make and model, 5,511.8 as pilot in command, 98.4 in the last 90 days, 40.5 in the last 30 days, 1.6 in the last 24 hours - Pilot; age 71; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review July 13, 2020; seat: left; restraint: 4-point; flight hours: 238.4 total, 6.8 in this make and model, 156.8 as pilot in command, 8.2 in the last 90 days, 4.9 in the last 30 days, 0.6 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 3 statute miles - Temperature: 22 °F, dew point 14 °F - Altimeter: 3005.00 inHg - Observed at: KEMT ## 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 20201103020659A](https://openairdocs.org/incident/20201103020659A), Nov 3, 2020: Stinson 108-3, El Monte, CA, Substantial damage. After landing during rollout, the aircraft began an un commanded veer to the left. The instructor pilot took control from the student and attempted to correct… ## Docket (5 files) The files NTSB released with the investigation on July 28, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102360. 3.6 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12246171&FileExtension=pdf&FileName=6120_1_Redacted-Rel.pdf - Manufacturer's installation instructions (item 2, PDF, 1 page, 197 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12259008&FileExtension=pdf&FileName=Installation%20Instructions-Rel.pdf - Annual inspection logbook entries (item 3, PDF, 1 page, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12258998&FileExtension=pdf&FileName=Annual%20Inspection%20Logbook%20Entries_Redacted-Rel.pdf - El monte airport operations general accident report (item 4, PDF, 1 page, 129 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12256366&FileExtension=pdf&FileName=Airport%20Operations%20General%20Accident%20Report-Rel.pdf - Photographs (item 5, PDF, 4 pages, 696 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12259099&FileExtension=pdf&FileName=Photos-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.