The Cessna L19 pilot reported that, during post-flight maintenance, he left the oil filler cap off.
During takeoff, he realized that the oil filler cap was not installed. He noticed a decrease in oil pressure and made a precautionary landing at an airport in Kennett, Missouri.
During landing, the plane landed hard, bounced, and the landing gear collapsed. The airplane skidded off the right side of the runway and ground looped to the right. The left wing hit the ground before the airplane stopped.
The airplane sustained substantial damage.
The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.
Probable Cause: The pilot’s failure to install the engine oil filler cap before the first flight of the day; his subsequent failure to conduct a preflight check before the accident flight, which resulted in his failure to note that the cap was not installed; and his improper landing flare during a precautionary landing, which resulted in a bounced landing and ground loop.
This September 2019 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.