Nose Gear Shimmy

Yesterday, after a routine landing with a moderate cross-wind (7-8 knots) I had a pretty severe nose wheel shimmy, which lasted until I turned off the runway. (The tower controller could see the shimmy taking place.) I later noticed that there was some black residue on the underside of the fairing behind the tire, which I think was from the tire going through a “hyper-wear” during the shimmy. Any experience with this?

I flew one of the prototype ac then it had 950 hours on it and that did the same thing.Man was it bad.The factory pilot said many do this.In fact the one I flew was the highest timed sr on earth.It flew better than any of that type I flew.

Upon further inspection, the residue on the bottom of the fairing is grease. Any idea where this came from?

Yesterday, after a routine landing with a moderate cross-wind (7-8 knots) I had a pretty severe nose wheel shimmy, which lasted until I turned off the runway. (The tower controller could see the shimmy taking place.) I later noticed that there was some black residue on the underside of the fairing behind the tire, which I think was from the tire going through a “hyper-wear” during the shimmy. Any experience with this?

Yesterday, after a routine landing with a moderate cross-wind (7-8 knots) I had a pretty severe nose wheel shimmy, which lasted until I turned off the runway. (The tower controller could see the shimmy taking place.) I later noticed that there was some black residue on the underside of the fairing behind the tire, which I think was from the tire going through a “hyper-wear” during the shimmy. Any experience with this?

Andy,

Was this an SR20 or SR22? I am sure that you know this but… a ‘soft field’ landing and ground technique is very helpful in reducing the effects of acute shimmy, reducing the tire ‘hyper-wear’ and keeping the fillings in your teeth!
Very low tire pressure can cause moderate shimmy. FWIW:Although I am not sure that it applies to the SR__'s free castering nose wheel structure, the nose wheel structure of the 172SP’s at the FBO that I rent from had nose wheel shimmy problems. The shimmy dampener had fluid leaks and the worn nose wheel shims had to be replaced.

I’ve experienced this shimmy. People, even a quarter mile away, can see the wheel swivel in an uncontrollable oscillation. It was frustrating because changing technique made no difference. The shimmy actually increases in severity as the plane slows, so it’s not too noticable during a touch&go and worst while slowing until almost stopped.

The problem was a loose fastener (bolt or nut, I don’t remember) on the strut, at the top (I think). There was a related service bulletin that also required checking the wheel bearing. Once we got things properly torqued the shimmy went away completely. Even a terrible landing didn’t matter!

It’s not your technique. Have the strut checked. It will only get worse if you don’t.

Kirk

Yesterday, after a routine landing with a moderate cross-wind (7-8 knots) I had a pretty severe nose wheel shimmy, which lasted until I turned off the runway. (The tower controller could see the shimmy taking place.) I later noticed that there was some black residue on the underside of the fairing behind the tire, which I think was from the tire going through a “hyper-wear” during the shimmy. Any experience with this?

This is another example of how useful, helpful, and safety-enhancing this forum is. Thanks for the help!

Andy

Yesterday, after a routine landing with a moderate cross-wind (7-8 knots) I had a pretty severe nose wheel shimmy, which lasted until I turned off the runway. (The tower controller could see the shimmy taking place.) I later noticed that there was some black residue on the underside of the fairing behind the tire, which I think was from the tire going through a “hyper-wear” during the shimmy. Any experience with this?

Yesterday, after a routine landing with a moderate cross-wind (7-8 knots) I had a pretty severe nose wheel shimmy, which lasted until I turned off the runway. (The tower controller could see the shimmy taking place.) I later noticed that there was some black residue on the underside of the fairing behind the tire, which I think was from the tire going through a “hyper-wear” during the shimmy. Any experience with this?

I have had this on a couple of occasions and it is very frightening.

It lasts until you are almost stationary.

Each time it was when I landed back after taking it for 100 hour check.

The recomended pressure to move the nosewheel in the maintenance manual is 10-15lbs. When I got mine checked by the shop at my home field it was 12lbs so they tightened mine to 15lbs. This was O.K. for a few landings then I suddenly got the shimmy again. I then rang the Cirrus dealer who did my service and he told me they allways set them at 20lbs which we then did to mine and so far no problems.

Why I twice came back from them with it set well below this I am not sure.

Robin

There is also an SB for the bolts holding on the nose gear–apparently they tend to be undertorqued, and fit a little bit loosely through the holes as well. The fix is to replace the bolts with slightly larger ones, and retorque them; if the holes show wear, they are drilled out to a larger size and bushings are added.

I’ve personally only experienced nosewheel shimmy in my SR22 once, after touching down in a crosswind while not being quite aligned with the centerline. (The POH warns about this.)

The Cirrus planes have the same landing gear arrangement the Grumman Tiger has. Having had one of those for years, I can give some advice (not withstanding the SB which should be checked) these types of gear are prone to doing this and you can effectively manage it. This arrangement gives excellent ground handling, is simple - but it does need to be watched.

1.Keep the sidepull for the gear to rotate at the upper end of the tension spec. Maybe a few pounds over to allow for wear, whch accumulates quickly.

  1. It is most likely to occur during a crosswind landing. The reason, the wheel cocks into the wind. It also can be aggravated by the pilot if you have any drift going on as you let the gear down.

  2. If it happens after all that the best way I have found to stop it is to lift the front wheel off the ground again with elevator (assuming you still have some elevator authority) or at least to get some weight off the wheel and let it settle down. Above all do not panic and stomp on the brakes, that just seems make it worse as the weight of the plane is shifted on to the front wheel more but the forces are still there.

It has not happened in the 22.

Roger

N706CD, SR 22

Yesterday, after a routine landing with a moderate cross-wind (7-8 knots) I had a pretty severe nose wheel shimmy, which lasted until I turned off the runway. (The tower controller could see the shimmy taking place.) I later noticed that there was some black residue on the underside of the fairing behind the tire, which I think was from the tire going through a “hyper-wear” during the shimmy. Any experience with this?

there is a brief description of the bolt, torque and adjustment for the nosewheel in the POH, training or service manual…i forgot where i read about the possible need for adjustment.

Don

]>>Yesterday, after a routine landing with a moderate cross-wind (7-8 knots) I had a pretty severe nose wheel shimmy, which lasted until I turned off the runway. (The tower controller could see the shimmy taking place.) I later noticed that there was some black residue on the underside of the fairing behind the tire, which I think was from the tire going through a “hyper-wear” during the shimmy. Any experience with this?

Andy,

Was this an SR20 or SR22? I am sure that you know this but… a ‘soft field’ landing and ground technique is very helpful in reducing the effects of acute shimmy, reducing the tire ‘hyper-wear’ and keeping the fillings in your teeth!
Very low tire pressure can cause moderate shimmy. FWIW:Although I am not sure that it applies to the SR__'s free castering nose wheel structure, the nose wheel structure of the 172SP’s at the FBO that I rent from had nose wheel shimmy problems. The shimmy dampener had fluid leaks and the worn nose wheel shims had to be replaced.

Hello Kirk,

Thanks for the help. I don’t have a nose wheel shimmy but I sure like to know which bolt to torque to improve the landing. Thanks in advance.

Have a great Cirrus landing day.

Woor

I’ve experienced this shimmy. People, even a quarter mile away, can see the wheel swivel in an uncontrollable oscillation. It was frustrating because changing technique made no difference. The shimmy actually increases in severity as the plane slows, so it’s not too noticable during a touch&go and worst while slowing until almost stopped.

The problem was a loose fastener (bolt or nut, I don’t remember) on the strut, at the top (I think). There was a related service bulletin that also required checking the wheel bearing. Once we got things properly torqued the shimmy went away completely. Even a terrible landing didn’t matter!

It’s not your technique. Have the strut checked. It will only get worse if you don’t.

Kirk

Yesterday, after a routine landing with a moderate cross-wind (7-8 knots) I had a pretty severe nose wheel shimmy, which lasted until I turned off the runway. (The tower controller could see the shimmy taking place.) I later noticed that there was some black residue on the underside of the fairing behind the tire, which I think was from the tire going through a “hyper-wear” during the shimmy. Any experience with this?

Holy smokes am I glad to see this thread. I am training in a 20 and have had some really nice landings get squirrely on me as I slow down to exit the runway. Once you start to veer, it’s tough to center up with out overcorrecting (think shopping cart) and before you know it you look like a drunk penguin from about 55-25 kts in the roll. I haven’t come close to swerving off the runway or anything, but there are some style points and ego dings I want to get rid of.

Come to think of it, this has not happened during touch and go landings or in soft field. I also noticed this did not happen during a flaps up landing (higher speed maybe?)

I will try soft field technique for several landings tomorrow and see if that fixes the issue.

Thanks guys

Get the nose gear tension adjusted before you break something.

+1 to what has been said and let me add that the G5s with the tubeless tires and Barringer wheels are experiencing a resonance vibration on takeoff in the nose gear. My 22 has had the torque adjusted as well as adjusting the strut and the vibration is less, but still there. I understand Cirrus engineers are all over this and my plane is in for its 50hour so I will report after I get her back. The shimmy will happen on crosswind landings as described if you are “drifting” some and for the reasons stated in this thread, but I think it is worse if your landing speed is high. If you can get to 80kts ish over the numbers and do a by-the-book landing with no side drift, it won’t happen. I think the whole idea is if the nose wheel is canted into the wind and you land a bit fast with some drift, bad shimmy is likely. I do all I can to keep nose wheel off the runway as long as possible in these conditions and that seems to help.

Bill,
By the axle definition you will not be able to increase wheel bearing tension. Caster tension is critical. Balancing the nose tire-wheel assembly is a huge help; if the tire has some damage to the plies or casing, this may NOT be detectable unless the tire is under load .
R
J

Thanks Jim – SC is looking at it again now and I will pass this on.

I’m flying from a fleet of well maintained but extremely high time planes. I don’t know which bird I am boarding until I get the keys. I’ll write it up for maintenance to take a look if/when this happens again. Weather and work have kept me down for the past 2 weeks and I am itching to get back at it.

Not to be a “ball-buster” but I had this identical problem just 3 weeks ago.

Low TP in the nose Was the culprit. I felt a stupid to say the least. Apparently, the warmer months contribute to more air loss than winter and requires more frequent checking. The tire looked absolutely fine from afar and close up. My local A&P explained that any added drag from LP will cause a shimmy. Seems logical.

I believe that a nose tire that is worn flat in the center of it’s tread (i.e. no longer “D” shaped on cross-section) can contribute to shimmy as well.

The nose tire, I think, needs to contact the runway near the center of it’s tread to remain lined-up with direction of travel. If first contact is lateral of the center, it can create a twisting force that kicks the nose wheel out to one side and initiates the shimmy.

Low tire pressure could probably have the same effect.

.

I chased a shimmy problem for a month and it came down to an out of balance new Goodyear Flight Custom III. Took about 1.5 oz of stick on weights to cure. Shimmy gone. Smooth as silk now. This is after adjusting fork tension to 28lbs, proper air pressure, checking wheel pant bracket for tightness, making sure the axel bolt was adjusted properly-all the usual suspects.