Good source for tubes?

[FastEddieB]

When Half Fast and I went to fly my Sky Arrow the other day, the right tire was very low.

 

Since I had just done an annual, and had the wheels apart, I guess I have to assume a MIF - Maintenance Induced Failure, though it's hard to see how. Very hard to pinch the tube between the wheel halves with some air in the tube. Did not seem to be leaking out of the valve, and even if it was I would think the o-ring on the valve cap would prevent air leakage there.

 

In any case, we pulled the tube and no damage was obvious. Inflated it and submersed it in a bathroom sink and no bubbles. Went ahead and reinstalled it and flew, and at least over that time span it held pressure.

 

But of course, I won't know for sure until I head back to the hangar in a day or so. Figure it can't hurt to go ahead and buy a tube (5.00x5) just in case.

 

Checked Desser Tire first. Anyone found a cheap, reliable source for tubes, other than them, and what brand have you guys settled on? Standard angled stem, BTW.

 

Thanks!

[Tom Baker]

Aero Classic Leak Guard. If you order just one tube you will likely have to pay shipping. I buy from Aircraft Spruce as a dealer, and I also buy from their FBO wholesale division. Desser has always had the lowest price on tires and tubes. Where I order from depends on what else I need at the time, and if I can place a large enough order to get free shipping.

[FlyingMonkey]

I always use leakguard tubes, and put some air in the tubes before (carefully) putting the wheels together.  I've done this maybe a dozen times, and I did pinch a tube anyway once and have to do the whole thing again.  It happens.   

 

In this case it sounds like maybe some grit in the valve, or something else?  

 

Definitely use the Leakguard tubes, they are great.  I have to order them from Desser, they are the only place I've found that has them for my little roller skate 400x6 tires.  The 600x6 tundra sized tires and tubes have more supplier options.

[FastEddieB]

Thanks for all the advice. I have two Aero Classic "Leakguard" tubes on the way from Desser.

 

And its a good thing. Went to the hangar this afternoon, and the right tire was noticeably bulging again after just two days.

 

Will look at the old tube more closely and update when I determine from where the air is escaping.

 

 

As an aside, the tire on the right is the Air Trak that the Sky Arrow came with, in 2010 after 210 hours:

 

 

Below is the Desser Monster retread now, after about 230 hours:

 

 

I think its fair to say they wear like iron!

 

Reminder, these are my 5.00x5 main gear tires. Not sure if in a larger size they're approved for a CT or not.

 

Again, thanks all for the help!

[FastEddieB]

Update...

 

Brought the tube home and finally found the leak.

 

Look at the bubbles along the seam to the left of the valve stem:

 

 

Curious is that there seems to be no sign of "insult" to that area once dried off:

 

 

So it remains a mystery. My working assumption is that a 6-year-old tube just failed along a seam from nothing other than removing and reinstalling it. Maybe the rubber is getting tired. Maybe a defect that just showed up now. Open to any other theories.

 

I will check the inside of the tire at the same position for anything suspect, but again, I don't see anything close to a puncture or slice.

 

Got the tubes I ordered Friday from Desser today. Probably tomorrow will get out to the hangar to throw one in. I'm going to leave the left one alone for now, but definitely swap it out next annual - if it goes that long.

[Anticept]

Tubes just fail after a while. The stem junction is the weak point and that's usually where I see it.

[FastEddieB]

The stem junction was the first place we checked - this is on an adjacent seam.

 

As a data point, this is a "Leakguard" tube, installed with the "Monster" retreads in 2010 and always talc'd.

 

Three asides...

 

1) I expected some tire talc from Desser - maybe they only ship it with tires, not tubes, or maybe they just don't provide it for free anymore. I've managed just fine in the past with Baby Powder, so that's what I'll be using this time.

 

2) I can see the bind mechanics can find themselves in. If I had paid for this annual and had a flat tire a few days later, it would be natural to blame the shop*. When, as best I can tell, technique had little or nothing to do with this failure. Anticept and others - is this something you have to deal with on a semi-regular basis?

 

3) Again, this was a six-year-old tube. Should they be replaced on a regular basis like the ROTAX rubber parts? If so, is every 5 years a reasonable guideline?

 

 

*"Post hoc, ergo propter hoc" - a very common logical fallacy.

[Anticept]

Baby powder might has a little oil in it, which doesn't play well with rubber. It's such a small amount though that it's likely inconsequential.

 

1- Yes, desser usually they ship the talk with tires.

 

2- Not over tires, no. Most people are understanding though. Those that aren't are not worth keeping anyways. They are the types that will throw you under the bus the first chance they get, and I've seen it done already on a different issue when they tried to get their way by involving the FSDO.

 

3- There are tubes on some aircraft that have lasted far longer. I'd say there isn't enough data to say that you should.

 

http://www.aircraftspruce.com/catalog/lgpages/tiretalc.php

[FastEddieB]

This should be the final follow-up...

 

1) The Sky Arrow is easy to jack up, with "naked" gear legs - though I guess that's another thing that adds to the drag and slows it down:

 

 

2) The wheel/tire/tube combo renders it nearly impossible to pinch the tube with just a little air in it:

 

 

3) Here's how the "Beemer Balancer" works - fits into a sock and all you need is somewhere to hang the string from:

 

 

More than one other mechanic has told me 6 years on a tube should be no issue - many tubes go far longer than that. Will probably still replace the left tube next annual if not sooner as the Most Conservative Action - just in case both were from a bad batch made with a weak seam. And I am calling Desser tomorrow to report what seems to be a defect in that one tube.