Yikes!  I went flying yesterday, and had a rather unique experience.  I rented a Cessna 172 to take up for a short cross-coutry hop for an hour or so, just to build up some time.  So I went to the airport and got the keys and AD's for the airplane, and did all my preflight checks and everything looked just fine.  The only thing I noticed was the nosewheel  looked like it was extened out too far, like someone was pushing down on the back of the airplane.  But this was a usual occurance when people tie the tail down too tight and the nosewheel doesn't settle back down when you untie it.  So I finished the preflight checks and taxied out and lined up at the end of the runway to take off.  I started my take-off roll, and everything was fine until I hit ~45 kts.  Suddenly the nosewheel started to chatter and shake the entire airplane, so I nudged the yoke back and lifted the nosewheel off the ground, which stopped the chatter, but by then I was at flying speed, so I continued with the take-off, and right when my back wheels left the runway, the airplane yawed to the left like I had jumped on the left rudder pedal.  When this happened, the nose jumped left and I rolled to the left because of the yaw, which was rather frightening 30ft above the runway.  So I jumped on the right rudder pedal to straighten back out and luckily everything went back to normal and I was able to climb out and stay in the pattern to come back and land.  I landed with the nosewheel off the ground for as long as I could keep it there, and luckily it dropped down below the chatter speed, and I went and parked it because I had had enough excitement for one trip.  The mechanics said it was probably the 'nosewheel shimmy damper' that was broken, which would explain all the nosewheel chattering, probably caused by a rough landing in the flight before (I wish those people would have maybe mentioned it or something ).  What I think happened was the nosewheel was off turned to the side when I lifted-off, and that caused the yaw, in addition to a bit of a crosswind.  I know it wasn't just the wind itself (unless it was an especially wicked gust), because I've flown in much worse winds than the wind yesterday.  Looking back I probably should have aborted the landing when the chattering started, hindsight is 20/20, but I'm happy with the way I handled it.  Oh well, it happens, and I'm still here to fly another day.

Edited:  Thanks Doug, I called it a chatter damper and it's a shimmy damper.

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Is there a way to check something like that without charging down the runway to see if it's broken.  One of the first times I went flying after I got my PPL, the flaps didn't work, so every time since then I've cycled the flaps before flying to check them, but there's no way to check a shimmy damper or something like it, is there?

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That's not on your preflight checklist? (just wondering)

Well, I suppose it's good to hear you're still with us Mobius   As Doug said, especially in aviation, live and learn.

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Interesting.  On our checklists its flip on the master, check the gauges, test the annunciator panel and put down the flaps.  Well, now you know

Yep, with our checklists, the only thing you do before preflight is flip the battery side of the master to check the fuel level the guages read so you can double check the if the fuel level guage reading and actual levels in the tank are the same.  Right after start-up though we check that the alternator is good, that all the guages are set and checked for correctness, and all the radios, nav. equipment, and transponder are set correctly and tested, and that's pretty much it.  Just curious, when do you guys test the flaps?  I always do it right after checking that the instruments are set, and right before the run-up, but it sounds like you guys are doing it before starting the engine.

And yeah, with that gust of wind, HERE is the weather history from yesterday, and right after I went flying is when the only gust of wind was recorded in that history.  The only other time I've had a gust that would even be close to that one would be when the new airport was being built a couple of years ago and we had to use the taxiway as the active, and one day there was a steady direct crosswind out of the south (runway is 28 ) and because the taxiway is so close to the FBO building, which is about 100 feet south of the taxiway, the wind was blocked right until the point where you were supposed to touch-down, so everyone would come in with x-wind correction, until the last minute when the wind was blocked, and to stay on the 30 ft wide runway, you had to straighten back out, then be ready to put that correction back in to touchdown.  On that day, I landed right before the building stopped, so right after touchdown that gust hit me and weather-vaned me into the wind, and I was about 3 feet from going off the left side of the runway, but I kept it on, and watched as the three people landing right behind me did the exact same thing.  The guy landing right behind me even asked me how my landing went (jokingly) so right after he landed and did the exact same thing, I had to return the favor.

Been there (nosewheel shimmy and uncommanded yaw); done that; got the soiled underwear,

The shimmy damper is basically a wee shock absorber, mounted usually on the right side of the gear leg, angled more or less horizontally so that it absorbs some of the energy produced by the nosewheel fork flexing or just shimmying for whatever reason.
Sounds like yours was stuck in the extended position (which would tend to force the nosewheel- and the rudder, because they're linked- to the left.
I was thinking at first that the over-extended strut was the culprit, but the damper is mounted on the upper part of that unit, so I'm not sure what happened to your damper, except that she's-a-no-good.

The usual left-turning tendency of a Cessna at high power but low airspeed just made it worse.

When anything at all seems amiss with the nosegear, it's best to not even taxi until someone looks at it, and if the maintenance guy shrugs, try a high-speed taxi test before commiting to takeoff.
And yes, don't tie the plane down in such a way that the strut is extended. That's not good for it.

I could be wrong about all this in your case, but I had a similar experience due to what I described above.


Here's an interesting article about the newfangled Lord dampers, which use neither gas nor fluid to do their thing; pretty cool idea!!

http://www.designnews.com/article/CA152921.html

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Taking my first lesson is still on my to-do list so please take my comments with a grain of salt.  I would suspect that you could be overly cautous with the "go ask someone" approach.  You could end up never getting off the ground.  After all,  you said it wasn't unusual to find a Cessna with an extended nose gear, and who knows how many other things could keep you on the ground at every walk around.  Aleron cables just slightly mis-colored, an ever so slight binding in the elevator, oil in the motor doesn't taste right, I'm sure the list is endless.  It's only in hindsight that you've noticed the nose wheel symptoms as problematic, and that means there probably was no apparent problem prior to flight, just some normal sounds and such.

Not that I'd recommend abandoning caution.  Healthy caution keeps pilots alive.  Heck, I visually look at my car's tires before driving and that's a vehicle that stays on the ground!

Also, you were at takeoff speed with a plane that you were confident would fly but didn't have confidence in the nose gear.  Why would you have reason to suspect the nose gear problems would sort themselves while in flight?  What better position would you be in after flight than you were in just prior?

I guess on landing you'd have a little more runway, and maybe be a little lighter but that's about it.  You'd be going a little faster at touchdown probably, potentially not be at an optimal (nose up) attitude, etc.  I think that your chances would have been better aborting the takeoff.

But that's hindsight.  And it's a complex decision to make in a split second.

We live and learn... and if we remember what we've learned, we live longer.

I've had some astonishing surprises while preflighting airplanes... the shimmy-damper thing is hard to detect sometimes; I found out about that the same way Mobius did.
There's nothing wrong with asking for advice- hell, if a wiser head thinks the plane's not fit to fly, why chance it? Which is more important: fly today, no matter what happens, or try to ensure that the next flight is trouble-free?

A good example: I have always been thorough with my preflight, but two critical things stick out in my memory...
first was the time my instructor decided to do his own inspection after I did, and discovered an aileron balance weight was missing. Might not have done any harm, but if it did...! Man, that would suck! Flutter; jamming. anyone? No? Me neither! I canceled my flight.
The other thing was when I was about to start up for a solo flight, and one of the CFIs ran out onto the ramp and told me to kill it. "did they fix that tube?" he asked... I didn't know what the hell he was talking about. turns out the brake fluid tube on one side had been badly crimped from hard landings (the main gear fairing was pressing down on it). I thought it looked OK, but he said "put your hand under there and feel it". I did, and my blood ran cold. It wasn't split yet, but it was close. Too close for my liking, as well as his. Another cancellation.

Now you can always pick me out on the ramp because I'm the guy who's fingering every nook and cranny of the plane...