SP Aircraft Cessna T210N accident
Cessna T210N · Accident: loss of engine power en route
From Slate Creek Airport (1S7) to Boise Air Terminal/Gowen Field (BOI)
Event
- NTSB case
- SEA00LA173
- 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
- 0
- 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 T210N
- Aircraft type
- Cessna 210
- 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
- N6993N
- Operator
- SP Aircraft
- Onboard fatalities
- Unknown
- Route
- From Slate Creek Airport (1S7), SLATE CREEK, IDTo Boise Air Terminal/Gowen Field (BOI), Boise, ID
- Aircraft age
- Not recorded
- 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 · cruise
- First occurrenceThe 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
- Loss of engine 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
- Company maintenance personnel › Maintenance, overhaul, major, improper
- Engine assembly, crankshaft › Fatigue
- Engine assembly, crankshaft › Fractured
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
While in cruise flight, the turbocharged aircraft's manifold pressure began to drop. Although the engine continued to run smoothly, the pilot elected to divert to an alternate airport in order to check things out. When the aircraft was about four miles from the alternate airport, the engine began to run rough, and ultimately ceased producing power. Although the pilot was able to touch down in an open field short of the airport, during the landing roll, the nose wheel encountered an area that had been softened by irrigation, and the aircraft nosed over. During the investigation it was determined that the crankshaft failed due to fatigue crack initiation in the number two main journal cheek. Further inspection revealed that a sealant had been applied to the mating faces of the main bearing saddles the last time the engine was overhauled. Application of this sealant, which is not called for in the engine overhaul manual, lead to a loss of proper crankcase clamping pressure in the area of the main bearing saddle through-bolts. Loss of this pressure resulted in bearing shift and scoring of the crankshaft journal.
Probable cause
the fatigue failure of the crankshaft due to improper overhaul procedures. Factors include a soft area in the field where the forced landing took place.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA00LA173
- Event ID
- 20001212X21877
- Case number
- SEA00LA173
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (5)
- 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: 8ad4bf41af3e42606d0fd090b6a93f4fb481e8239463fbf679a41abf1522f9fd; retrieved 2026-09-18T16:27:25.718Z.
- The NTSB's operator name is blank for N6993N; the operator shown is the name the NTSB records it doing business as.