CEN17LA057 · Stinson 108-3
Stinson 108-3 · Accident: system/component malfunction/failure (non-power) during takeoff
From Lowell City Airport (24C) to Ionia County Airport (Y70)
Event
- NTSB case
- CEN17LA057
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Stinson 108-3
- Aircraft type
- Stinson 108
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N812C
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Lowell City Airport (24C), Lowell, MITo Ionia County Airport (Y70), Ionia, MI
- Aircraft age
- About 69 years (built 1947)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Takeoff
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- System/component malfunction/failure (non-power)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft oper/perf/capability
- Aircraft › Aircraft systems
- Aircraft › Fluids/miscellaneous hardware
- Personnel issues › Task performance
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The private pilot reported that, shortly after takeoff from a snow-covered runway, he heard a "thump" and saw that the left main landing ski tip had rotated up, past vertical, and was in contact with the left wing strut. He was unable to reposition the left ski into a normal position. Upon landing, the ski separated from the axle, the left gear leg dug into the snow, and the airplane rapidly decelerated before it nosed over.
As designed, the main landing skis are supported by two 5/32-in braided steel cables and bungee/shock cords. Both ends of the steel cables terminate with a thimble-eye and a compressed/swaged nicopress sleeve. On the accident airplane, the forward and aft support cables had pulled through their respective nicopress sleeves where the cables attached to the left ski's tip and tail. The nicopress sleeves for the left ski tip and tail attachments were not located during the investigation. However, a postaccident examination of the remaining nicopress sleeves established that they were likely improperly formed with a 3/16-in swage tool instead of a properly-sized 5/32-in tool. As a result, the steel support cables were able to pull through the inadequately-formed nicopress sleeves during the accident flight. It is likely that the aft support cable pulled through its nicopress sleeve during takeoff, which allowed the ski to rotate into a vertical position. The forward support cable likely pulled through its nicopress sleeve when the left ski separated from the axle during the subsequent landing.
The pilot reported that the airplane was typically equipped with snow skis during the winter. He purchased the main landing skis in used condition, with an undocumented service history, from an individual about 8 years before the accident. The forward and aft support cables were already fabricated and installed on the skis when they were purchased. Additionally, the pilot reported that the support cables had not been repaired or replaced since he owned the skis. The pilot, who was also an aviation mechanic, installed the main landing skis for the winter snow season 2 days before the accident. The accident occurred during the first flight since the skis were installed for the season.
Probable cause
A failure of the aft support cable on the left main landing ski due to an inadequately formed nicopress sleeve, which allowed the ski to rotate into a vertical position shortly after liftoff, and its unavoidable separation during the subsequent landing.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN17LA057
- Event ID
- 20161219X04338
- Case number
- CEN17LA057
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 65fe07e0531be509c7d02af20b6431203c5d764413e4731f7661178c6229dc73; retrieved 2026-09-16T04:54:06.411Z.