Strong vibration in the cockpit during takeoff right before and during rotation

[JCMP]

I am new to this forum, just got a DA62 at the beginning of the year.

During my last two takeoffs I have been feeling a very strong vibration inside the cockpit coming from the front gear (as if the runway is full of small bumps) right before rotation. As soon as I reach 70-75 knots and the plane wants to start to fly, the strong vibration begins a progressively becomes stronger until I rotate usually at 85-90 knots. Right after rotation the vibration hits it maximum level and continues for a few seconds once I am flying, then stops.


During landing, if I land with the mains and hold the nose gear up until I slow down and then drop it I don’t feel the vibration, but If I land on the mains and immediately the front tire touches the ground with speed, I feel the same vibration until I slow down.

Tire pressure is ok, everything on the front gear looks fine and tight. There is not a flat spot on the wheels.

Please help! Any advise would be much appreciated!

[Rich]

First guess would be the nose-wheel is out of balance or worn nose gear bearings. Cheap to correct. Next would be something else worn/loose in the nose-gear strut, actuators, etc. Not so cheap.

[pisymbol]

Sounds like wheel bearings to me. What happens after you rotate and hit the brakes briefly?

[JCMP]

Thank you Rich and pisymbol, nothing seems loose or worn in the nose gear. Vibration is gone before I have the time to press the brakes and retract gear. Next take off will pay close attention to it.

This morning I will take it to the mechanic so he can use jacks and lift the nose wheel to asses the problem.

Will keep you posted.

Appreciate your help!

[Colin]

There are no brakes on the nose wheel, are there? Or maybe that is an upgrade from the DA42 to DA62?

[JCMP]

That’s correct Colin, no brake on the front wheel.

Problem solved finally! The counterweight inside the tire was loose, I believe it’s a manufacturer defect. That little thing was creating an unbalance on the tire generating a very strong vibration at fast speed on the runway.

I replace the tire for a new one and problem solved!

Thanks a lot to everybody for the help!