C-150 nose wheel shimy ?

[Throtlemonkey]

How can I stop it, ive tried all different pressure in the oleo different oil viscosity's in the smimy "dampener", all to no avail the bloody thing still shakes, I'm sure this can't be good for the engine mounts the instruments or my back. Also has the effect of frightening first time flyers.

Can anyone help ?

[Kermit 180]

We had this problem with a few of our 152's. The only solution that worked was to get the nose strut, oleo and shimmy dampener rebuilt.

Kermie :(

[Hudson]

Nose wheel shimmy in the C150/152 seems a perennial problem. Suggest you join the Cessna Pilot Association via their website. Known as CPA. Cost you around US$55 a year but well worth it for excellent advice. Once joined then pose your question re nose wheel shimmy. CPA will immediately give you a comprehensive list of step-by step maintenance fixes to give to your maintenance organisation. Or go into their archives and locate the shimmy fix that way.

Meanwhile make sure that you rotate at the correct speed stated in the manufacturer's Pilot Operating Handbook, and avoid touching down too fast. To be quite blunt about it, you should not be flying the aircraft if you know that nose wheel shimmy is going to occur. The aircraft is actually un-airworthy until you rectify the situation.

You can also cause serious damage to various components including engine mounts. Then in a few months time, some poor blighter may have the engine fall off - all because the owner could not be bothered to spend the money to fix the problem.

I suggest that once you have the defect looked at, that you flight test it first before taking up fare paying students. There are serious legal ramifications involved if a student gets scared fartless with the shimmering and a'shakin, and goes you for stress and trauma. It would be easy money for him, particularly if his lawyer could prove that your aircraft has had a history of the problem yet you have continued to fly it for hire and reward.

[kabz]

Arrrgghhhh. Nose wheel shimmy. On one of my first tngs, the nosewheel of the 172 I was flying went into a mad shimmy. I really badly wanted to shut the engine down and stop as, not knowing what was happening, I imagined the prop was about to come off.

However, I looked at my instructor, and he said keep going. On takeoff, the shimmy mercifully stopped. Phew.

I believe one of our students encountered bad shimmy on a first solo, and ran it off the runway as a result in panic. Scarey. Not sure if I quite believe this was the whole story, as could shimmy really make the plane that uncontrollable ??

[Low_and_Slow]

For nose-wheel shimmy, servicing the shimmy dampner is generally only fixing the symptom, not the problem. I'd try the following:

1) check all the steering components are tight. They loosen up and can end up with a good deal of shimmy inducing play.

2) Replace the tire, paying special attention to the red dot on the tire and line on the tube, followed by a spin balancing (if you don't have the machine, a local motorcycle place might be able to help with this).


-me

[cudgy_funt]

All ive been told is to pull back on the control column to reduce the weight on the nosewheel. Miht not be the best course of action from readin previous posts, but it does work.

[P.Pilcher]

I've had the problem many times from the instructor's point of view - Eventually the maintainance organisation will twig to it. If the shimmy damper is not worn and all oil levels and air pressures are correct, the oleo has to be re shimmed to make it stiffer to turn. This crude method works a treat and has no effect on the ground nosewheel steering. The problem is frightening however as when it gets really bad, no amount of up elevator during the landing roll will cure it.

[Trash Hauler]

Alluded to already but I will add my 2 cents worth.

The damper will only work if all the other parts are OK. Play in the attach bolts, bushings etc particularly on the torque links will cause most of the shimmy problems even with a good tyre. Remember these wheels don't get balanced like an auto wheel.

Cheers

:eek:

[Hudson]

I know one bright spark of a Grade One Australian CFI that would drop the nose wheel tyre pressure to 15PSI and said that stopped the nose wheel shimmy in his C150. He said it was cheaper than repairs to the system. My flying school refused to cross-hire his aircraft after that.

[Snakum]

A local flight school where I worked weekends had a 152 that shimmied pretty badly after an overhaul. The strut components, oils, and tire were all gone over with a fine-tooth comb, with no luck dampening the shake. It was so bad every take-off was a soft-field :o)

I was told by a respected local wrench that if, during replacement of the engine after overhaul, the motor mounts and other assorted bracketing get tweaked a little too much and not uniformly torqued this can cause severe shimmy that appears to be unrelated to the nose wheel components. Is there an inexpensive way to check the mounts and bracketing?

Snakum