I am based out of Key West International where there is a 15-knot direct crosswind most of the winter. I land my SR22 as recommended, crabbing on final and straightening it out just before touch down. Still, I often end up with a horrendous shimmy on the ground roll. The UND Aerospace instructor who trained me here says this is normal with a castering nosewheel in a crosswind. Normal or not, I don’t like it, and it is cracking the nosewheel pant. Any advice? I have 600 hours in Cessnas prior to the SR22 so I understand there will be a transition time.
Jeffrey Cardenas
Jeffrey,
Are you holding the nosewheel off the ground as long as possible?
I’ve landed in lots of crosswinds at 15 knots or higher and have never noticed shimmy.
The one and only time I have experienced a relatively minor shimmy is when I was practicing a “no-flap” landing – I came in faster than normal, and flatter than normal. So the nosewheel touched the ground at a higher speed than it normally would (oops!), and it caused some shimmy.
If that’s not the issue, then maybe your service center should check the torque of the nosewheel. I was starting to get a real slight shimmy (more like a vibration) in my nosewheel a few months ago, took it to the shop, and now it’s all better again.
Steve
Jeff,
Have your shop check the nosewheel sidepull spec. It is pretty broad, something like 15 to 21 lbs… (don’t quote me, its something like that). Have the shop set the sidepull a tad over the spec because after a few landings it will relax to the upper end of the spec. BTW, that is permissible (according to the factory service center here anyway) if you have to to get the cotter pin it the castalated nut. My plane will lightly shimmey when it gets down to the lower end of the spec and will not shimmey in crosswids at or above the max demonstrated crosswind component if set as described. I have worked on these before, but on the Cirrus under warranty I have let them do it, so thats why the numbers are approximate.
That tension from the bellview washers is what serves as a shimmey damper on Cirrus airplanes. I used to own a Grumman Tiger and it has the same system and the same tendancies. Same fix too. Touch the nose down gently at a low speed. Also when it shimmeys, lift the nosewheel off the ground if you still have elevator authority. If it wont lift, it will at least unload the gear and that helps tremendously. That slow/stops it, but stepping on the brakes hard only aggravates it. My experience anyway, your milage may vary. But when operated and adjusted as above, I NEVER experience shimmey.
In reply to:
I land my SR22 as recommended, crabbing on final and straightening it out just before touch down.
Jeffrey,
Personally, I prefer to get rid of the crab at around half-mile final, and forward slip from there, so that I land with the upwind main touching first and the fore-aft axis of the airplane in line with the runway centerline. Plenty of time to set it up, no last-minute anything to be done just before touchdown, and a predicably good result each time.
Some pretty decent crosswind landings done; no shimmy problems. Mine’s a '20.
Mike.
I just recently had the same problem. I routinely land at Boca with a crosswind, in fact a week ago Tuesday was the worst, 90 degree 15 kts, no problems. However on Friday doing touch and goes at Pompano that shimmy came back and popped the 2 screw holes that had been repaired 40+ hours ago. I got a similar response from the St Augustine service center about adjusting the nose wheel.
All good suggestions! Also, make sure your nose wheel is fully inflated.
Jeff, I have to agree with Roger, In our fleet we check the nose wheel side pull tension any time a pilot reports any shimmy at all. I have found that it does loosen up every so often. In addition to having the tension reset, you should have the belville washers and thrust washer removed and cleaned with alcohol. Dirt, grime, and oil get in between those washers and act as a lubricant. They must be clean and dry. This extra step only takes a few extra minutes since they have to pull the cotter pin anyway to tighten the nut. In my experience, ignoring a shimmy gives you about three more flights before the rear half of the nose fairing departs the aircraft on landing. I also recommend installing stainless dimpled washers under the heads of all screws on the nose wheel fairing in order to spread the loan and stop the screws from pulling through.
I’ll second Mike’s comments (except that I would describe the slip as a sideslip rather than a forward slip, since the slip is into the crosswind - but what the heck - a slip is a slip!) Holding the nosewheel off until the speed has bled off certainly makes for smoother landings. I would suggest that yawing the plane just before touchdown could make the nosewheel swing, so stabilizing the approach well beforehand should minimize any nosewheel funniness.
In reply to:
…I would describe the slip as a sideslip rather than a forward slip, since the slip is into the crosswind…
Clyde,
You’re quite right! Thanks…
Mike.
Clyde, Mike
What you suggest about crosswind landing makes sense. I was just wondering if it conflicts with the POH which says under crosswind landings “Crab into the wind until in ground effect… Avoid prolonged slips”
Why does it say this - because slips could lead to fuel not draining properly into the fuel lines and fuel starvation. Any other reason?
Cheers Tony
BTW Clyde - Nice, quick work on the fly-in. I will get back to you when I check with Liz whether it will be 1 or 2 of us.
In reply to:
Why does it say this - because slips could lead to fuel not draining properly into the fuel lines and fuel starvation. Any other reason?
Tony,
No other reason I know of.
I have a couple of comments on “prolonged slips”:
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Not sure what they mean by “prolonged” - by slipping for the last 1/2 mile at final approach speeds in my '20, I’m doing it for less than 30 seconds;
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I experimented with this at altitude when I did my “run a tank dry” experiment, when my left tank had > 20 gallons and my right tank had ~ 5 gallons remaining. I found that I could starve the engine of fuel if I slipped so that the right wing was as low as I could get it with full rudder deflection at 100 kts, but it took about two minutes to happen. I could not “unport” the left (fairly full) tank with sideslip after three minutes of slipping with that wing low.
So… when I slip on final approach, I make sure I have the “high” tank selected, and I’m confident that a fuel problem is most unlikely. I do try to switch to the appropriate tank long before turning final, though!
Mike.
Good points Mike.
As you recall the fuel system on both the '22 and '20 have header/collector tanks inboard of the mains. I believe that they hold either 3 or 5 gallons, but either way, they would be somewhat difficult to unport. But that would be a function of time in uncoordinated or otherwise unusual flight attitudes and the power setting/fuel flow.
Marty