Probable cause
A total loss of engine power due to detonation/preignition damage of the No. 2 cylinder and piston for reasons that could not be determined.
NTSB analysis
The pilot reported that shortly after takeoff, as he began to configure the airplane for cruise flight, the engine began to run rough and lose power, and he elected to immediately return to the airport. The engine subsequently lost total power and the pilot performed a forced landing on tundra-covered terrain, during which the airplane sustained substantial damage.
Examination revealed that the No. 2 piston was eroded on the bottom side, and a hole was burned through. The No. 2 piston and cylinder head were mechanically damaged by loose piston ring debris. Closer examination of the No. 2 cylinder head revealed re-solidified molten metal around the bottom Heli-Coil tang notch. All damage discovered was consistent with a pre-ignition/detonation event; however, the cause of the pre-ignition and/or detonation could not be determined based on the available information.
Text from the NTSB. Open the NTSB docket for ANC18LA064 for the full record.
Event
- Date
- Aug 7, 2018
- Type
- Accident
- Place
- Iliamna, Alaska
- Nearest airport
- Iliamna Airport (PAIL)
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Cessna 207
- N-number
- N7379U
- Category
- Airplane
- Year built
- 1978
- Damage
- Substantial
- Operating rule
- Part 135 (charter and commuter)
From the NTSB aviation accident database: N-registered aircraft, events since 2008, data through Oct 28, 2026. The file is published monthly, so the latest weeks are incomplete and recent records can change. The official source is the NTSB aviation investigation search. CheckAero is independent and not affiliated with the NTSB.