70 North Cessna TU206 accident
Cessna TU206 · Accident: powerplant system/component malfunction/failure en route
From Badami Airport (AK78) to Deadhorse Airport (SCC)
Event
- NTSB case
- ANC14LA085
- 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
- Charter & commuter
- 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
Cessna TU206
- Aircraft type
- Cessna 206
- 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
- N206J
- Operator
- 70 North
- Onboard fatalities
- Unknown
- Route
- From Badami Airport (AK78), DEADHORSE, AKTo Deadhorse Airport (SCC), DEADHORSE, AK
- Aircraft age
- About 47 years (built 1967)
- 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 135: Air Taxi & Commuter
- 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
- En route
- 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
- Powerplant system/component malfunction/failure
- 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 power plant
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The commercial pilot was conducting an on-demand air taxi commuter flight. The pilot reported that, during cruise flight, the engine began vibrating violently and lost power and that the throttle and propeller controls were unresponsive. The cockpit subsequently filled with smoke. The pilot conducted a forced landing to the nearest and driest tundra patch, during which the airplane nosed over.
Examination of the engine revealed a large hole on the top left side of the crankcase near the No. 2 cylinder. The No. 2 connecting rod had separated from the crankshaft connecting rod journal. The No. 2 main bearing support mating surfaces exhibited fretting damage. The No. 2 main bearing had shed material from its forward side and had shifted. Measurements of the breakaway torque on the cylinder through bolts indicated that the torque on the Nos. 2 and 3 cylinder through bolts was below the engine manufacturer's specification. It is likely that the insufficient torque on the Nos. 2 and 3 cylinder through bolts resulted in the fretting damage and the No. 2 main bearing shifting and interrupted the oil flow to the No. 2 connecting rod bearing. The interruption of oil flow resulted in the bearing becoming starved of oil and overheating and the subsequent separation of the connecting rod from the crankshaft.
A review of maintenance records revealed that the No. 1 cylinder was replaced about 403 flight hours before the accident, which would have required the removal and installation of hardware on the Nos. 1, 2, and 3 cylinder through bolts. It is likely that insufficient torque was applied to the through bolts during the replacement of the No. 1 cylinder.
Probable cause
The application of insufficient torque to the engine cylinder through bolts during the replacement of the No. 1 cylinder, which resulted in the displacement of the No. 2 bearing, oil starvation, and a catastrophic engine failure.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ANC14LA085
- Event ID
- 20140922X52015
- Case number
- ANC14LA085
- 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. 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: 98e520cc65892788ce2c6439907d0cd5345dd6ef8ea8c76fa52701814fb4d44f; retrieved 2026-09-16T01:47:01.706Z.