Pilot Debrief

Cessna 207 near Iliamna, AK — 2018-08-07

Final reportANC18LA064
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Date
2018-08-07
Location
Iliamna, AK, USA
Airport
PAIL
Aircraft
Cessna 207
Registration
N7379U
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Initial climb

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 narrative

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.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have aborted the flight after initial engine roughness.

NTSB coding

Evidence available

  • Photos
  • 5 docket documents
View NTSB final reportView NTSB docket

Docket documents5

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