ANC01IA058 · Cessna 207
Cessna 207 · Incident: total loss of engine power (mechanical failure) en route
From Platinum Airport (PTU) to Bethel Airport (BET)
Event
- NTSB case
- ANC01IA058
- 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
- Incident
- 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
Cessna 207
- Aircraft type
- Cessna 207
- 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
- N917AC
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Platinum Airport (PTU), PLATINUM, AKTo Bethel Airport (BET), Bethel, AK
- 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 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
- En route · descent
- 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
- Total loss of engine power (mechanical failure)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Minor
Cause areas
- Engine assembly, crankshaft › Fractured
- Lubricating system, oil port/passage, internal › Flow restricted
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The certificated commercial pilot reported that during a flight earlier on the day of the incident, he had difficulty controlling the propeller rpm, so he elected to make a precautionary landing. The pilot related that after a mechanic replaced the propeller governor, the airplane's engine and governor appeared to be operating normally, so they began their flight back to the operator's base. He said that about 10 minutes after departure, while in cruise, level flight, he noted a light sheen of oil forming on the windshield, and he elected to make a precautionary landing on a remote beach. As he retarded the throttle to start the descent, the propeller rpm increased for about 20 seconds, followed by the propeller detaching from the engine. He said that he was able to glide the airplane to the beach, and land without further incident. The airplane was equipped with a Teledyne Continental Motors (TCM) IO-520-F engine. The propeller and engine crankshaft flange were eventually recovered, and sent to the NTSB metallurgical laboratory for examination. A Safety Board metallurgist examined the fractured crankshaft flange, and reported that his initial visual examination revealed a fatigue fracture, originating from a heat check site. A postincident investigation revealed that the engine crankshaft had been replaced by TCM, 94.3 hours before the crankshaft separation. An engine log book notation, entered by TCM, indicated that the reason for removal was: "...for compliance with CSB 99-3A." According to a representative from TCM's in-house analytical laboratory the crankshaft was a remanufactured part that reportedly was ground undersize, and re-nitrided at TCM. In the presence of an NTSB Investigator, the engine was disassembled. The investigator noted a significant amount of heat discoloration, with modest circumferential scoring of two forward most bearings, just aft of the fractured propeller shaft, indicating a localized loss of lubrication. He added that the oil transfer collar assembly was fractured in one location.
Probable cause
An in-flight fracture of the engine crankshaft during descent, precipitated by restricted oil flow through an internal engine oil passage/port.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ANC01IA058
- Event ID
- 20010605X01080
- Case number
- ANC01IA058
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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: local date, investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2001-05-18.
- API snapshot SHA-256: 1e7216dfa86b5a0d9d8a60122c7b5dc9e7c90958226e0b7bd1b8682f0e456049; retrieved 2026-09-22T11:57:17.529Z.