I had a real world flying experience yesterday and I wanted some of your world class advice or insight. I was flying the Diamond DA-20 C-1 as I have done dozens of times. The whole flight was normal and everything went great right up until I touched down. The mains tocued down softly and as the nose came down, the whole aircraft started to shake violently. Enough that I thought things inside were going to break off. I figured maybe it was a blown tire. So thinking that things were fine before the nose went down, I went back to the way things were and pulled back to get pressure off the nose wheel. I didn't let on to my passenger (mom as a matter of fact!) that I was concerned about anything and I kept the plane under control. I taxied off the active and got to a nearby spot on the ramp. The tires were fine. My dad who was watching near by said that when he saw us touch town the, nosewheel began to shimmy and he could hear it from quite a distance away. Do you have any idea what could have caused that? And was getting pressure off the nose a good thing to do? I've always been taught if you do something and it has a negative result, put things back the way they were.
CAP flyer is correct. I've not flown the Katana and am not familiar with the nosewheel design but my guess would be a shimmy dampner. This was a real problem on Cessnas used for training, especially 150's and 172's back when. The solution when this happens is to get the flaps up, raise the nosewheel a bit to take the pressure off Use a bit of power if you need it and have the room, then ease the nose down gently using subtle rudder pressure for directional control.