Remember awhile back in my infamous 185 thread when I complained of awful (I mean really really bad) ground handling and tons of tailwheel shimmy? Take a look at this!





That to me and my mechs look like a messed up tail spring that should be replaced. Harry seems to think it can bent back into shape. I'm a bit sketched out about that and have no problem with finding a replacement. So far it looks like my options are a replacement 1" spring or an upgraded 1.125" spring. If I were to upgrade to the 1.125" spring, I'd consider getting the ABI kit as its less spendy than the TLGW kit. The thing that bothers me is that their spring has increased arch to help with shimmy. It looks as if my spring was bent to help remedy the shimmy, but it just made everything worse. If it were to be replaced with the ABI spring, wouldn't I just run into the same issue again but now be a few thousand dollars lighter? Open for opinions.

I'm curious is the Tony fellow who told you not to worry about it and fly it (on your FB thread) your mechanic? Or is he the guy who "fixed" this plane for you the first time?
On the spring, I'm not sure how that bend would cause shimmy, unless its bent sideways as well. It has put the geometry of the TW where it should be. Not saying I'd be comfortable with the bend though. I'd replace it with the 1.125 version and be confident you won't have a failure, especially with the loud bang you heard back there on one if your flights...

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Your tailwheel bolts are different colors.

A1Skinner wrote:I'm curious is the Tony fellow who told you not to worry about it and fly it (on your FB thread) your mechanic? Or is he the guy who "fixed" this plane for you the first time?
On the spring, I'm not sure how that bend would cause shimmy, unless its bent sideways as well. It has put the geometry of the TW where it should be. Not saying I'd be comfortable with the bend though. I'd replace it with the 1.125 version and be confident you won't have a failure, especially with the loud bang you heard back there on one if your flights...

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There were way too many Tonys involved! Tony G (from FB) is the guy who set the whole thing up. He only spent a month working on it though. The spring looks to be straight with no twist, however it feels weird where the bend is. Hard to describe it. Completely forgot about that bang back there! I'll be sure to look for any clues when I do SEL 55-01 which is when I'll replace the tailspring.

asa wrote:Your tailwheel bolts are different colors.

Only temporary until I can get a tie down right back there!

+1 for replacing it, regardless of whether it fixes the ground handling.

I have leaf springs on the 170, and I replace them every 500 hours, though they show no damage. On one hand it's a waste of money, but on the other it's fantastically cheap in comparison to having one break, especially in the bush.

That bend in your tail spring is completely in the wrong direction. According to ABW the “axis” of the tailwheel being the bolt that everything pivots on needs to be as close to perpendicular to the ground as possible to avoid shimmey. Maybe you can turn that tail spring 180 degrees to upside down from what it is now. I would think the bolt holes would line up. From the looks of your pics, it seems as though that may make the axis perpendicular to the ground. Is it possible the tailspring was intended to be installed that way and it is currently installed incorrectly? Also make sure the pivot is snug to the point of just less than not being able to steer it while taxing and keep your tailwheel tire pressure as low as possible.

49_sedan wrote:That bend in your tail spring is completely in the wrong direction. According to ABW the “axis” of the tailwheel being the bolt that everything pivots on needs to be as close to perpendicular to the ground as possible to avoid shimmey. Maybe you can turn that tail spring 180 degrees to upside down from what it is now. I would think the bolt holes would line up. From the looks of your pics, it seems as though that may make the axis perpendicular to the ground. Is it possible the tailspring was intended to be installed that way and it is currently installed incorrectly? Also make sure the pivot is snug to the point of just less than not being able to steer it while taxing and keep your tailwheel tire pressure as low as possible.

Not sure if this is a joke, but if not, you have it backwards

http://www.airframesalaska.com/v/vspfil ... ention.pdf
https://backcountrypilot.org/forum/inte ... shimmy-687
https://backcountrypilot.org/forum/180- ... ching-9349

X2. You want positive castor, that way when you are loaded at GW you are still a bit positive or neutral. You never want to he negative. If he flips the spring around it would be almost always negative, making shimmy even worse.

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I was thinking that it is to much positive and that flipping it around might make it closer to neutral while still being on the positive side. I may be wrong though especially with loading being taken into consideration.

I think you have missed that the tubular tailwheel spring on a skywagon has about a 20 degree bend in it where it comes out of the tail cone. Upside down would immediately be obvious. You can see what it looks like on the Alaska Bushwheel or Landing Gear web site.

Tim

Yes I was under the impression that it was straight other than the small bend at the wheel end(at least in this case)

Probably stating the obvious here, but you should replace that tail spring ASAP. That's a pretty major non-original bend which probably required a lot of heat to make, likely leading to metallurgical badness right at the point of greatest stress on the spring.

pilotryan wrote: Remember awhile back in my infamous 185 thread when I complained of awful (I mean really really bad) ground handling and tons of tailwheel shimmy? Take a look at this!....

Do you still have the shimmy going on?
There can be other causes of tailwheel shimmy besides the angle of the dangle.
1) check t/w axle, the nut's gotta be just right-- not too tight, not too loose.
2) check kingpin nut (the one that holds the fork on)--
ditto re "juuust right". I usually tighten this one as tight as I can, get back it off about 3 flats and try it.
IToo tight and it's hard to steer, too loose and it shimmies.
And not every time-- sometimes the shimmy onkly shows up when you have a lot of weight on the tail.
Unlike the axle nut, it usually takes some trial-and-error to get the kingpin just right.

I agree with OR180's "badness" assessment, that spring looks pretty iffy to me.
Re upgrading to a bigger spring-
Landing Gear Works sells new springs, both 1" and 1-1-1/8" are $2625.
If you go bigger, you'll need a new tailwheel assembly: $4-5K at LGW.
Dunno if they sell just the head--they do offer a "overhaul" of the head for $1100,
but I dunno if they'd include boring it out for the larger spring as part of that.

If you do go bigger, and I'm sure you will, this would be the time to upgrade to a BBW -
or maybe the LGW set-up that uses a 500x5 tire.

https://tlgw.aero/

49_sedan wrote:Yes I was under the impression that it was straight other than the small bend at the wheel end(at least in this case)

That's ok. Never having peered up into the guts of the Skywagon nether region, I would also assume it's a straight tube.

Best lesson is to not makes public guesses on matters not intimately known. But who can stick to that credo? We all do it here, all the time. It's fun but then someone comes along and tells you you're wrong and you go crack open a beer and try to forget about BCP for a few hours.

https://anchorage.craigslist.org/avo/d/ ... 68826.html

Gary

Sorry 49_Sedan, I didn't mean to imply that you should know what the spring looks like, and the photo definitely doesn't show that part of the spring. Each of us knows more about the aircraft we own than other aircraft and I am sure you know things about a Sedan I don't even have the slightest idea about. That is what makes this community so valuable, if you ask, someone probably knows. Actually the spring is fatter in the middle and tapers to both ends. The bend in the middle is just aft of where the saddle that attaches the spring to the aft bulkhead attaches to the spring, so it is actually near the forward end of the tailcone. A undamaged or not modified spring has no bend where the tailwheel head attaches. I know a couple of guys that have broken tailwheel springs on skywagons in the same place as where the bend is shown on Ryan's. One had his break while pushing the airplane back into the hangar. If it were mine I wouldn't fly the airplane till it was replaced and if necessary would only taxi very slowly.

Tim

PA1195 wrote: https://anchorage.craigslist.org/avo/d/ ... 68826.html

Is there an outfit that does some sort of NDT on these stingers-- eddy-current, magnaflux, whatever?
The price on that one ($400) is sure attractive vs new ($2600), but it might have (probably has?) a gazillion hard hours on it.

Zzz wrote:Best lesson is to not makes public guesses on matters not intimately known. But who can stick to that credo? We all do it here, all the time. It's fun but then someone comes along and tells you you're wrong and you go crack open a beer and try to forget about BCP for a few hours.

I keep learning this one the hard way. Getting better at not doing it though!

Tailspring will be replaced in the spring. Definitely gonna grab the wide fork and 400x4 glider tire when I do it. The airplane might look a little dumb with a YUUGE tail wheel and tiny tires up front. Guess it’ll just be begging for bushwheelz.

Hotrod180, in addition to NDT testing the holes through the spring require inspection. One of the things that happen to these springs is that the two holes through the spring where the saddle attaches wear resulting in the tailwheel rocking side to side around the axis of the spring which leads to shimmy.

Tim

hotrod180 wrote:……Landing Gear Works sells new springs, both 1" and 1-1-1/8" are $2625.
If you go bigger, you'll need a new tailwheel assembly: $4-5K at LGW.....

Airframe Alaska offers C180/185 tailsprings (no size listed) at a somewhat lower price than TLGW -- $2,195.

http://www.airframesalaska.com/Cessna-1 ... 2152-2.htm

FWIW a wide fork kit for the 3400 lists at $1,145 with a baby BW--
no price shown for the kit with a 400x4 tire but I believe it's $300-350 cheaper.