20240101000519I

(Statement from pilot)

Upon entering the pattern, I tried to lower the landing gear and upon checking the gear indicator light I observed that the nose gear was indicating that it was not down. I headed back to Santa Rosa. Upon contacting the tower, I informed them that I wanted to do a fly by and have them confirm the gear. After the low pass and the tower confirming that the nose gear was still up, I climbed above the airport and did some troubleshooting (cycled gear, tried dump valve, did high g pull ups) all with no success. The tower went ahead and declared an emergency for me and had the fire trucks waiting on runway 02. I next tried a relatively hard touch and go hoping to dislodge the nose gear but without success. I then went around the pattern and performed a nose gear up landing. After touchdown I kept the nose up as long as I could before the nose dropped to the runway and we skidded to a stop.

Background: prior to the incident, on December 23, 2023, I completed the installation of a new machined nose wheel fork with shimmy damper. Velocity airplanes have had many documented cases of nose wheel shimmy events that result in the landing gear leg or cast aluminum fork failing. The original nose fork required tightening the bellville washers so that it took approximately 15 lbf to rotate the fork and prevent shimmy. The new fork assembly with damper requires minimal force to turn the plane when taxiing. After installation of the new fork assembly, the gear was cycled without incident and a test flight was performed verifying proper function.

Findings: after having the airplane removed from the runway and returned to my hanger, I observed a small mark on the side of the nose gear fork. I then put the plane on jacks and cycled the gear. I observed that the nose fork assembly can rotate slightly in both directions within the wheel well. When the fork rotates to the right and the gear is lowered, the edge of the fork can catch on the corner of the tray that supports the backup battery. (See images below)

Conclusion: with the installation of the new nose gear fork assembly, it is believed that the fork assembly rotated in the wheel well. This rotation probably resulted from the free castering of the nose fork along with the angular momentum of the spinning nose wheel. Once the fork had rotated it became locked against the battery tray preventing extension of the landing gear. To eliminate the issue the battery tray will be modified to remove the corner that the fork was catching on.