CESSNA 206 near King Salmon, AK — 2024-06-07
- Date
- 2024-06-07
- Location
- King Salmon, AK, USA
- Aircraft
- CESSNA 206
- Registration
- N756CL
- Category
- Airplane
- Highest injury
- None
- Fatalities
- 0
- Phase of flight
- Initial climb
Probable cause
A partial loss of engine power due to detonation/preignition of the No. 1 cylinder for reasons that could not be determined.
NTSB narrative
The pilot reported that, shortly after takeoff, he observed high engine oil temperature and began to turn back to the airport. The engine began losing power, and the pilot performed a forced landing in the tundra, which resulted in substantial damage to the horizontal stabilizer and elevator. Examination of the engine revealed that the No. 1 piston was eroded down to the steel ring lands and scuff marks were observed on the side of the piston skirt. The No. 1 cylinder upper and lower spark plugs had molten aluminum deposits covering the electrodes and insulators. The crankshaft rod journals exhibited evidence of foreign material contamination in the oil. The Nos. 2 and 5 crankshaft rod journals had severe thermal discoloration. All connecting rod bearings exhibited abnormal wear. Connecting rod bearings No. 2 and 5 were severely damaged. The observed damage was consistent with a detonation/pre-ignition event; however, the reasons for the detonation/pre-ignition could not be determined based on the available information.
Analysis
- Primary failure mode
- Engine power loss
- First missed decision gate
- Pilot could have performed a more thorough preflight engine check.
NTSB coding
Evidence available
- Photos
- 6 docket documents