# NTSB CEN20LA377: Stinson 108-3, N909C, Coleman, MI, September 1, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: September 1, 2020, 11:00 local (15:00 UTC) - Place: Coleman, MI - Coordinates: 43.756668, -84.58583 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.7567&lon=-84.5858&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA FSDO - NTSB case key (mKey): 101913 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN20LA377 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101913/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101913 - Page: https://openairdocs.org/ntsb/CEN20LA377 ## Probable cause The pilot’s improper installation of the generator drive gear, which resulted in a total loss of engine power. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Ignition system: magneto/distributor](https://openairdocs.org/ntsb-findings/01057414): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Stinson 108-3, 2 cases](https://openairdocs.org/ntsb-findings/01057414/cases.md?model=9230408), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/01057414/cases.md) - [Inspection: post maintenance inspection](https://openairdocs.org/ntsb-findings/02061515): Personnel issues › Task performance · Maintenance personnel; cases with it: [Stinson 108-3, 1 case](https://openairdocs.org/ntsb-findings/02061515/cases.md?model=9230408), [All aircraft, 57 cases](https://openairdocs.org/ntsb-findings/02061515/cases.md) - [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Stinson 108-3, 3 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=9230408), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Aircraft maintenance event](https://openairdocs.org/ntsb-events/040); cases with it: [Stinson 108-3, 2 cases](https://openairdocs.org/ntsb-events/040/sequence.md?model=9230408), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md) - [Prior to flight: Aircraft inspection event](https://openairdocs.org/ntsb-events/050); cases with it: [Stinson 108-3, 2 cases](https://openairdocs.org/ntsb-events/050/sequence.md?model=9230408), [All aircraft, 229 cases](https://openairdocs.org/ntsb-events/050/sequence.md) - [Enroute-cruise: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Stinson 108-3, 1 case](https://openairdocs.org/ntsb-events/340/sequence.md?model=9230408), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Stinson 108-3, 5 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=9230408), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Stinson 108-3, 15 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=9230408), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot had been flying for about 45 minutes when the airplane experienced a total loss of engine power. The pilot performed a forced landing onto a field. The airplane nosed over and sustained substantial damage to the fuselage and empennage. Postaccident examination of the engine revealed that the single generator drive gear for the ignition system had separated into several pieces. The drive gear shaft installation called for a castellated nut with a cotter pin to retain the drive gear, but the cotter pin had not been installed and allowed the nut to back off, which ceased ignition to the engine. The generator was installed by the pilot, who did not hold a mechanic certificate, during his overhaul of the engine. The pilot stated that he performed the overhaul of the engine and installation of the generator under the supervision of a mechanic with an airframe and powerplant ratings. No other mechanical anomalies with the engine were noted. ## Factual narrative On September 1, 2020, at 1100 eastern daylight time, a Stinson 108-3, N909C, was substantially damaged when it was involved in an accident near Coleman, Michigan. The pilot was uninjured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that the airplane had been flying for about 45 minutes before it experienced a total loss of engine power. The pilot then performed a forced landing to a soybean field, where it rolled for about 180 ft and nosed over resulting in substantial damage to the fuselage and empennage. Postaccident examination of the engine, by a Federal Aviation Administration representative, revealed the single generator drive gear for the ignition system had separated into several pieces. The drive gear shaft installation called for a castellated nut with a cotter pin to retain the drive gear, but the cotter pin had not been installed and allowed the nut to back off. The generator was installed by the pilot, who did not hold a mechanic certificate, during his overhaul of the engine. The pilot stated that he performed the overhaul of the engine and installation of the generator under the supervision of a mechanic with an airframe and powerplant ratings. No other mechanical anomalies with the engine were noted. ## Aircraft - Registration: [N909C](https://openairdocs.org/aircraft/N909C), registered now, S/N 108-3909, built 1947 (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: 108-3909 - Year built: 1947 - Airframe hours: 1804 - Engines: Franklin 6A4165 SERIES 165 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Pilot - Airworthiness certificate: Standard, Normal; Standard, Utility - Departed: 53W, Remus, MI - Destination: 53W, Remus, MI ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 70; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review October 29, 2018; seat: left; restraint: 3-point; flight hours: 148 total, 16 in this make and model, 77 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Lowest ceiling: none ## 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 20200901009449A](https://openairdocs.org/incident/20200901009449A), Sep 1, 2020: Stinson 108-3, Coleman, MI, Substantial damage. On September 1, 2020 at 11:45 eastern daylight time (EDT), a Stinson 108-3 aircraft, N909C, registered to [privacy data omitted] and operated by a private… ## Docket (3 files) The files NTSB released with the investigation on June 10, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101913. 1.2 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 926 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13173842&FileExtension=pdf&FileName=ntsb%206120.1%202_Redacted-Rel.pdf - Record of conversation - FAA (item 2, PDF, 1 page, 108 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13184602&FileExtension=pdf&FileName=RECORD%20OF%20CONVERSATION%20Anderson-Rel.pdf - Photo log (item 3, PDF, 1 page, 154 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13185278&FileExtension=pdf&FileName=Photo%20Log-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.