# NTSB DEN89LA082: Stinson 108-2, N150C, Custer, SD, March 7, 1989

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: March 6, 1989, 17:30 local (Mar 7, 1989, 00:30 UTC)
- Place: Custer, SD
- Coordinates: 43.760253, -103.599998 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=43.7603&lon=-103.6000&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report May 22, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 17678
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN89LA082
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17678/pdf
- Page: https://openairdocs.org/ntsb/DEN89LA082

## Probable cause

THE IMPROPER MAINTENANCE BY THE PILOT IN COMMAND/OWNER IN THAT THE MAGNETO DRIVE GEAR RETAINING NUTS WERE NOT SAFETIED WHICH RESULTED IN THEM BACKING OFF, DISCONNECTING THE MAGNETOES AND ONE OF THE GEARS FALLING INTO THE ENGINE.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of engine power(total) - mech failure/malf, takeoff - initial climb
  - ignition system,magneto - not safetied (cause)
  - ignition system,magneto - disengaged (cause)
  - maintenance,installation - improper, pilot in command (cause)
- Forced landing, descent - emergency
- Hard landing, landing - flare/touchdown
  - terrain condition - loose gravel/sandy

## Analysis

THE PRIVATE PLT WAS PERFORMING A FLIGHT FOLLOWING HIS INSTALLATION OF TWO MAGNETOS. A WITNESS AND THE PLT REPORTED THAT ON CLIMB OUT THE ENGINE QUIT. THE PLT SAID HE HEARD SOMETHING BREAK IN THE ENGINE. THE PLT ATTEMPTED TO LAND ON A GRAVEL DRIVEWAY SOUTH OF THE RUNWAY. AT IMPACT, THE MAIN LANDING GEAR COLLAPSED. THE PLANE CAME TO REST AFTER SLIDING 150 FT. A POST ACCIDENT INSPECTION REVEALED THAT BOTH MAGNETOS HAD BEEN INSTALLED WITHOUT COTTER PINS ON THE DRIVE GEAR RETAINING NUTS. THIS RESULTED IN THE NUTS BACKING OFF, DISCONNECTING THE MAGNETOS, AND ONE OF THE GEARS FALLING INTO THE ENGINE, RESULTING IN THE REPORTED STOPPAGE.

## Aircraft

- Registration: N150C (not matched to a registry record)
- Reported make and model: STINSON 108-2
- Category: Airplane
- Serial number: 108-3150
- Airframe hours: 1356
- Engines: FRANKLIN 6A4-165-B3 165 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: James R. Winter
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, January 27, 1989, 3 hours before
- Departed: SD01, CUSTER, SD
- Destination: SD01
- Airport: SD01, Custer County

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 54; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 600 total, 600 as pilot in command, 40 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 25 statute miles
- Lowest ceiling: none
- Temperature: 50 °F

## 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 19890306003129A](https://openairdocs.org/incident/19890306003129A), Mar 6, 1989: Univar 1082, Custer, SD, Substantial damage. Engine failed on climbout. Crash landed. Installed magnetos without drive gear safety pins. A nut fell into engine.

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.

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