Probable Cause: A loss of engine performance due to carbon fouling of three spark plugs that, when combined with the airplane’s high gross weight condition, resulted in a collision with trees and terrain.
NTSB Report
Plane Not Flown for 25 Years Makes Forced Landing When Insect Nest Clogs Fuel Vent Line
Probable Cause: A total loss of engine power due to fuel starvation as a result of a fuel vent line that was clogged by an insect nest.