Dehavilland DHC-2 MK.I N218RD accident near Oak Island, Minnesota

Probable cause

The failure of an O-ring in the landing gear system, which resulted in the inadvertent extension of the main wheel in the amphibious float. Contributing to the accident was the pilot’s decision to depart with a known hydraulic leak in the landing gear system.

NTSB analysis

Before the flight, the pilot added hydraulic fluid to the reservoir due to a known leak in the airplane’s amphibious float landing gear system. At some point during the flight, the left rear wheel extended and protruded from the float. The pilot was unaware of the wheel position and landed on the water near his residence. During the water landing, the wheel contacted the water, and the airplane’s nose and propeller assembly immediately went into the water. The pilot and passengers exited the airplane, and the airplane subsequently flipped over. During the accident sequence, one passenger sustained vertebrae fractures, and the airplane sustained minor damage.

Due to the remote accident location, the airplane was not examined; however, the pilot provided photos of the landing gear system problem area and a short video demonstrating the leak in the system. According to the pilot, the leak was the result of a failed O-ring in the lower hydraulic fitting on the jack assembly.

Text from the NTSB. Open the NTSB docket for CEN21LA244 for the full record.