STINSON 108

Ninilchik, AK — July 13, 2023

Event Information

DateJuly 13, 2023
Event TypeACC
NTSB NumberANC23LA051
Event ID20230717192643
LocationNinilchik, AK
CountryUSA
Coordinates60.03361, -151.65077
AirportNINILCHIK
Highest InjuryNONE

Aircraft

MakeSTINSON
Model108
CategoryAIR
FAR Part091
Aircraft DamageSUBS

Conditions

Light ConditionDAYL
WeatherVMC

Injuries

Fatal0
Serious0
Minor0
None1
Total Injured0

Event Location

Probable Cause

A partial loss of engine power due to failure of the No. 1 cylinder intake valve head.

Full Narrative

On July 12, 2023, about 1624 Alaska daylight time, a Stinson 108 airplane, N97719, was substantially damaged when it was involved in an accident near Ninilchik, Alaska. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. 

The pilot stated he departed Homer Airport (HOM) destined for Anchorage, Alaska. A few miles northwest of the Ninilchik Airport (NIN) he noticed a loss of engine power and the oil pressure decreasing. The pilot determined he was too far from the NIN airport to return so he elected to perform a forced landing to a road. During the landing roll the right wingtip struck a traffic sign, which resulted in substantial damage to the right wing.
 
Postaccident examination of the engine revealed the No. 1 cylinder was fractured from the engine and remained partially attached by exhaust tubes and the intake manifold. The intake valve head and stem was fractured about an inch from the interior base of the valve. The piston and intake valve were destroyed by the internal forces in the engine and the fragments were not located.
The pilot reported the engine had a total time of 626 hours at the time of the accident. The last annual inspection was completed 12 months before the accident at an engine total time of 556.4 hours. The engine logbook showed the manufacturer’s recommended time between overhaul is 1,200 hours.

About This NTSB Record

This aviation event was investigated by the National Transportation Safety Board (NTSB). NTSB investigates all U.S. civil aviation accidents to determine probable cause and issue safety recommendations to prevent future accidents.

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