Mike S
Senior Curmudgeon
For some time now I have experienced the dreaded "shopping cart shimmy" upon landing.
This has been quite intermittent, maybe once in every 10 or so landings.
Most of us have heard or read about the problem, and I would guess that a few of the nosedragger folks may have experienced it.
When this first happened to me, I checked the nose wheel breakout and found it to be a bit light so I snugged up the nut one flat. Seemed to take care of the problem.
When it happened again, I checked the breakout and it seemed to still be good, so I looked at the tire inflation, roundness balance etc. Ended up adding a few PSI, and all seemed fine again------
Now, I need to say that this has only manifested itself on landing roll out after I let the nose wheel down. Classic scenario.
Well, yesterday I had the shakes again, but this time it was while still rolling along with the nose wheel off the runway ---- riding on the mains only as per the recommended technique from Vans. We had 3 on board, so there was a bit of an aft CG shift, and I could keep the nose off just a bit longer, instead of my normal two up landing profile.
Turns out it was a main wheel that was causing the vibration, not the nose wheel.
This time the vibration did did not just shake for a moment and go away, it shook like a wet dog, and then the plane made an instant bee line for the right side of the runway---- Luckily I missed the landing light that was there.
A neighbor who happened to see the entire sequence unfold said the right wheel pant was shaking as I was landing. And then it came loose and tucked under the wheel.
Lets see, one side of the plane rolling happily along, and the other side with a wheel pant jammed under the wheel skidding along-----no wonder we headed off to the dirt.
Luckily I got the plane under control prior to any secondary issues from the swerve-----even kept it mostly on the pavement.
Here is what was left of the wheel pant after going back to pick up the pieces.
And no, there is not a big chunk of fiberglass not in the photo, there is a lot of fiberglass dust still on the runway from being ground into a fine powder under the wheel. Notice the scuffed areas adjacent to the big hole in the nose.
Here is the bracket where the pant used to be attached-------anyone who had built a 10 can attest to the fact that this piece of metal is tough, and not easily bent.
They say confession is good for the soul, and I believe that.
Confession however is not going to fix the plane, that is going to take time work and $$$, which is the entire point of this thread-------dont get tunnel vision when you have something going on that does not seem right.
Perhaps this confession will keep someone else from having a similar problem, or even worse..............
I focused on the nose wheel, as I knew it had to be the problem-----after all, I had read about it many times, and the problem only happened when I let the nose back down on roll out.
In retrospect, I am pretty sure the main wheel was the issue all along, and that the shimmy was speed related, and due to the fact we almost always fly with only the two of us, the speed range just happened to be below where I could keep the nose wheel off------the addition of the third person allowed the plane to stay on the mains only, until the speed dropped down to shimmy range this time.
And just to make matters worse, this happened on the last flight before I planned to start my "annual" inspection prior to OSH.
For those who are thinking that I should have checked the wheel pant for being loose as a part of the preflight------I do, and it was not loose. In fact, the bracket is still mounted tightly.
I hope others can learn from my mistake-----------if you dont find the problem where you "know" it to be, dont get tunnel vision, start looking somewhere else.
Take care, fly safe.
This has been quite intermittent, maybe once in every 10 or so landings.
Most of us have heard or read about the problem, and I would guess that a few of the nosedragger folks may have experienced it.
When this first happened to me, I checked the nose wheel breakout and found it to be a bit light so I snugged up the nut one flat. Seemed to take care of the problem.
When it happened again, I checked the breakout and it seemed to still be good, so I looked at the tire inflation, roundness balance etc. Ended up adding a few PSI, and all seemed fine again------
Now, I need to say that this has only manifested itself on landing roll out after I let the nose wheel down. Classic scenario.
Well, yesterday I had the shakes again, but this time it was while still rolling along with the nose wheel off the runway ---- riding on the mains only as per the recommended technique from Vans. We had 3 on board, so there was a bit of an aft CG shift, and I could keep the nose off just a bit longer, instead of my normal two up landing profile.
Turns out it was a main wheel that was causing the vibration, not the nose wheel.
This time the vibration did did not just shake for a moment and go away, it shook like a wet dog, and then the plane made an instant bee line for the right side of the runway---- Luckily I missed the landing light that was there.
A neighbor who happened to see the entire sequence unfold said the right wheel pant was shaking as I was landing. And then it came loose and tucked under the wheel.
Lets see, one side of the plane rolling happily along, and the other side with a wheel pant jammed under the wheel skidding along-----no wonder we headed off to the dirt.
Luckily I got the plane under control prior to any secondary issues from the swerve-----even kept it mostly on the pavement.
Here is what was left of the wheel pant after going back to pick up the pieces.
And no, there is not a big chunk of fiberglass not in the photo, there is a lot of fiberglass dust still on the runway from being ground into a fine powder under the wheel. Notice the scuffed areas adjacent to the big hole in the nose.
Here is the bracket where the pant used to be attached-------anyone who had built a 10 can attest to the fact that this piece of metal is tough, and not easily bent.
They say confession is good for the soul, and I believe that.
Confession however is not going to fix the plane, that is going to take time work and $$$, which is the entire point of this thread-------dont get tunnel vision when you have something going on that does not seem right.
Perhaps this confession will keep someone else from having a similar problem, or even worse..............
I focused on the nose wheel, as I knew it had to be the problem-----after all, I had read about it many times, and the problem only happened when I let the nose back down on roll out.
In retrospect, I am pretty sure the main wheel was the issue all along, and that the shimmy was speed related, and due to the fact we almost always fly with only the two of us, the speed range just happened to be below where I could keep the nose wheel off------the addition of the third person allowed the plane to stay on the mains only, until the speed dropped down to shimmy range this time.
And just to make matters worse, this happened on the last flight before I planned to start my "annual" inspection prior to OSH.
For those who are thinking that I should have checked the wheel pant for being loose as a part of the preflight------I do, and it was not loose. In fact, the bracket is still mounted tightly.
I hope others can learn from my mistake-----------if you dont find the problem where you "know" it to be, dont get tunnel vision, start looking somewhere else.
Take care, fly safe.
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