Thorp Air Command - T18.net

So, this morning I thought I would do some flyin. I did my usual preflight which does include a close look at the skins. I taxied out, did my run up and proceeded to try to turn her into the wind an all I got was a wubba, wubba, wubba and the tail lifted! Flat tire! So this is my third flat in three years with the thorp. I’ve gone through both tubes and tires so an aged tube shouldn’t be a problem. No signs of F.O.D., no torn valve stems. I run 30 PSI. New tubes.

The only thing of any note is that all three have been on the right side. The right gear leg does have a slight misalignment issue as the right inside tread does wear faster and necessitates tire rotation.
This is my first flat under steam and it has made me figure if I get a flat during the landing/takeoff cycle it’s probably going to get expensive and I’d rather not leave it to the whim of unreliable rubbers.

So my question is WTF? Three tubes in three years? That isn’t normal is it? What am I doing wrong?

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http://www.dixiefriedfabrication.com/

Lou, have you inspected the tube to see where the leak/hole is. I suspect that you have burr on the wheel halves or loose crossbolts .Something is "working" the tube. Ruff place or FOD inside tire . Three flats on the same tire is a lot. I have never had a flat on my Thorp in 20 years except when I pinched the tube when putting a new tire on

My thought also...some type of "burr" inside the rim ? Is the hole always in the same place ? When you talk about tire rotation , exactly what do you do ?

Definitely not normal, Lou. I just recently changed out my tires & tubes for only the 3rd time in 24 years. I have averaged around 600 hours on a set of Goodyears, & could have run them longer but I'm pretty conservative.

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

OPP’s has a dolly and the guy’s helped me push it back to the hanger, approximately 2000 feet and about 100 degrees out. I was able to swap out the tube, make my run to AC spruce and score a burger. Ac Spruce has a smoking hot new parts runner.
Anywho, due to the fact that the inside of the right tire wears much faster than the rest I have to swap sides with the tires maybe every six months, so some were around 50 hrs. So, if you’re doing the math I’m buying new tires once a year (or so) I’m better at “goinflying” than I am at keeping logs.
As I just finished my annual, the previous flat/new tube (and tire) went over to the left side. So, todays flat was in a different tire than the last one.
Today’s flat was caused by a tiny hole in the “sidewall” of the tube. I could not find anything wrong/inside the tire. I can’t find anything wrong with the wheel. The tube is dated 08 but was put into use about a year ago.

The last flat I had was about two months ago. I found a quarter size area on the side of the tube that was perforated with super tiny holes. As I could not find a thing wrong with the tire I wrote it off as a bad tube, but now I’m starting to get a little pissed.

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http://www.dixiefriedfabrication.com/

600 hours!!! I’ve got 136 hours out of the cheapy tires. The Goodyear’s have 102 hrs, better landings, fewer touch & go’s and they are about toast.

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http://www.dixiefriedfabrication.com/

Buy good tubes. I use Michelins and the bonus is you only air them about once a year. You tire wear problem is wheel alignment. Shim stock is cheap. I get all I need out of one beer can. Underinflation and bad alignment can build up a lot of heat during taxi. One degree out of track (toe out) drags your tire one foot sideways for every sixty feet you taxi.

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Bob Highley
N711SH
SN 835
KLAL

You might try to correct the misalignment with shims if possible. The airplane should handle better & the tires will last longer too.
I've heard that the Desser retreads are really long lasting and affordable. Don't know what tubes you've been using, but I haven't been impressed with the "Leak-Guard" tubes I got from Desser to go with my Goodyear tires this last time. Quality control seemed poor - the valve stems were out of alignment & different between the 2 tubes. It was a pain in the a..! I should have gotten the Goodyear butyl tubes. I'll see how these do over time. Your multiple tiny perforations sound like a possible manufacturing defect. Either that, or you've got some weird rubber-eating microbes in your air supply!

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

Oops... I guess Bob was posting a reply just before me. Michellins are good.

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

I got my tires and tubes from Dresser . The "Leak Guard" tubes were stamped "Made in Mexico ." I have not had any problems with the tires or tubes . My tires wear evenly on both sides . I did read some where that there may be a problem with the tubes (leaks) made in Mexico during certain years ? Don't hold me to this , do your own research .

My current tires and tubes came from Van's, they had the least expensive price. I don't know the brand of the tubes but I've only had to add air once a year there bouts. Been really happy with them. I have about 200 flight hours on this set.

Is there a write up on how to do a tire alignment some where?

inquiring minds want to know.

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Bruce Finney
N18JF T-18C #262
Yelm, WA USA

Could be diaper rash. Do you use talcum powder when you put the tubes in?
Sounds like you definitely need an alignment. You won't regret doing it as it will probably handle a lot better and you won't have to use as many of your expert piloting skills.

Bernie Fried
N18XS

Alignment...yes . There is a write up in the NL's and I think there is one in a "Tiger Tales" issue ? I must have been lucky with the gear that came with my project as I didn't need one . Both tires wear very evenly .

NL #48 main gear alignment , by Dr. Shinn . NL#74 Ground Handling by Dave Eby . "Taming the Tiger's Tail" Checking toe In/Out . Check Camber and tail wheel alignment . Dan is this where you got the idea to "tilt" your tail wheel vertical axel forward ?

To reiterate what Bernie said......baby powder!.....generously.....and check burs on wheel parts.

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)