- Date
- September 1, 2020, 11:00 local (15:00 UTC)
- Place
- Coleman, MI
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N909CStinson 108-3
- Defining event
- Enroute-cruise: Powerplant sys/comp malf/fail
- Weather
- Visual (VMC) · Day
- Status
- Completed
- Report
- Approved by Office Director
- Investigation class
- Class 3
- NTSB office
- Central Region
- Parties
- FAA FSDO
- FAA report
- 20200901009449A
- Case key
- 101913
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The pilot’s improper installation of the generator drive gear, which resulted in a total loss of engine power.
Findings · 3
NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.
Sequence of events
The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.
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
- Reported as
- Stinson 108-3
- Category
- Airplane
- Serial number
- 108-3909
- Built
- 1947
- Airframe hours
- 1,804
- Engine
- 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
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 70
- Injuries
- None
- Certificate
- 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
Docket · 3
The files NTSB released with the investigation on June 10, 2022, on NTSB’s docket system: statements, records, photos and specialists’ reports. 1.2 MB in all.
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.