Frequent Inner Tube Failures

[FlyingMonkey]

Makes perfect sense for your Alaska scenario!

[Ed Cesnalis]

I've used it in my CT, and it was a no-hassle solution.

[FlyingMonkey]

I've used it in my CT, and it was a no-hassle solution.

 

Cool...maybe I'll pack one in the emergency maintenance kit.

[procharger]

I have the Tundra tires and have removed both for inspection, 90 degree valve stems, the holes in the rims are larger than the stems ,I saw a lot of wear on the stem itself the metal part had worn a lot from vibration I guess???

[procharger]

FD should allow screws in the rims for bead lock like drag cars?

[Doug G.]

If you look at the rating printed on the Desser 4x6.00 tire you will find that it is rated for a70mph max. about 61kts.

[FastEddieB]

If you look at the rating printed on the Desser 4x6.00 tire you will find that it is rated for a70mph max. about 61kts.

 

Good catch!

[Ian]

....Also, air temperature has a factor on still tires. When it gets cold, air condenses as we all know and the tire pressure will drop. When it warms, air expands and so does tire pressure. .....

 

You're right of course that temperature has an effect on tyre pressure, though not that much

 

The gas equation PV=nRT shows that for a constant volume then pressure is directly proportional to temperature, but the key is that you are counting temperature from 0 degrees Kelvin (absolute Zero)

 

So if say your ambient at ground level is 20 Deg C (293 deg K) (sorry but the rest of the world doesn't use Fahrenheit any more ) and you climb to where it is say 10 Deg C (283 deg K) then the difference in pressure in %age terms will be (293-283)/293 * 100 = ~3.4%

 

Then using that if you take off with a pressure of 35psi, that will reduce to ~34psi for that 10 degree drop in temperature.

Of course the issue is that we are likely to be at altitude for some time with a relatively quick descent which is unlikely to give the tyres chance to warm back to ambient so your landing pressure is virtually always going to be less than your T/O pressure hence Roger's advice of making sure your tyres are correctly inflated is extremely good.

[Steven]

It would be interesting to take a survey to find out just how often inner tubes are failing, on average. As I posted initially, I've experienced 3 tube failures in the past 2 years and the tubes were 1, 3 and 4 years old at time of failure.

 

My prior plane was a Cessna Skyhawk and through 5 years I did NOT experience a single inner tube or tire failure.

 

My experience represents just a tiny statistical sample, but it certainly seems from the posts on this subject that the frequency of inner tube failures is very high in the CTLS and presumably other LSA's.

 

I do perhaps 50 miles of taxiing per year, so the average mileage on my failed inner tubes was a mere 133 miles !

 

Can you imagine if car tires would routinely fail after 133 miles of use ??? Long distance commuters would need tire changes on a daily basis ! Utterly unacceptable and quite a joke really.

 

Yes, car tires and aircraft tires are subject to different types of stresses (especially the instantaneous acceleration at aircraft touchdown), but I can't help but be perplexed by the seeming low quality and deficiency of LSA aircraft tubes. A CTLS costs 10x as much as an average car, yet the tire tubes fail at a 500x greater frequency if measured in terms of mileage. I'd gladly pay $1000 for 3 tubes guaranteed to last 10 years and it would still represent less than1% the cost of the plane.

[FlyingMonkey]

 

I do perhaps 50 miles of taxiing per year, so the average mileage on my failed inner tubes was a mere 133 miles !

 

Can you imagine if car tires would routinely fail after 133 miles of use ??? Long distance commuters would need tire changes on a daily basis ! Utterly unacceptable and quite a joke really.

 

Yes, car tires and aircraft tires are subject to different types of stresses (especially the instantaneous acceleration at aircraft touchdown), but I can't help but be perplexed by the seeming low quality and deficiency of LSA aircraft tubes. A CTLS costs 10x as much as an average car, yet the tire tubes fail at a 500x greater frequency if measured in terms of mileage. I'd gladly pay $1000 for 3 tubes guaranteed to last 10 years and it would still represent less than1% the cost of the plane.

 

They are designed for entirely different things. Car tires are steel belted radial construction, which is optimized for high speed cruising. Aircraft tires use fabric belts and thinner treads. This saves weight, but has a large impact on wear and handling. Honestly, if you ran an aircraft tire on the ground at 70mph continuously, I bet you would not make half of the 133 miles you referenced; they are just not designed for that kind of operation. They are designed for taxiing around at 15-30mph and having short periods (usually a minute or less) of 60-80mph long enough to get an airplane off the ground or back down and slowed to that slower taxi speed.

 

As for the difference between your CT tires and the Cessna tires, that is a valid question I don't know the answer to. It sounds like there is something in your configuration causing problems, either pinched tubes, low pressure, thin tubes, or something else.

[Tom Baker]

I have had tube failures before, but I don't think I have had one since I switched to the Aero Classic 4.00x6 tires and tubes from Desser.

[Jim Meade]

I have had tube failures before, but I don't think I have had one since I switched to the Aero Classic 4.00x6 tires and tubes from Desser.

 

+1

[Steven]

They are designed for entirely different things. Car tires are steel belted radial construction, which is optimized for high speed cruising. Aircraft tires use fabric belts and thinner treads. This saves weight, but has a large impact on wear and handling. Honestly, if you ran an aircraft tire on the ground at 70mph continuously, I bet you would not make half of the 133 miles you referenced; they are just not designed for that kind of operation. They are designed for taxiing around at 15-30mph and having short periods (usually a minute or less) of 60-80mph long enough to get an airplane off the ground or back down and slowed to that slower taxi speed.

 

As for the difference between your CT tires and the Cessna tires, that is a valid question I don't know the answer to. It sounds like there is something in your configuration causing problems, either pinched tubes, low pressure, thin tubes, or something else.

 

The issue from my perspective is much too high a failure rate in the CTLS / LSA aircraft inner tubes. Granted, aircraft tires and auto tires are very different, but the failure rate should be MUCH LESS for an aircraft tire/tube than for an auto tire, yet the OPPOSITE is true. I'd be pretty disgusted with my auto tires if I had experienced 3 flats in just 2 years. I'd be replacing them with the best tires I could buy !

 

It seems to me that the LSA aircraft tubes are cheap and deficiently designed. They DON'T do the job. The tires are fine .... they don't fail .... it's the tubes that fail.

 

I would point out again that a new CTLS costs $160,000+, 10x what an average car costs, and it's a big shame to have unworthy tire tubes on such an expensive vehicle.

[Roger Lee]

The failures I have seen usually come from runway or taxiway debris or low tire pressure resulting in a stressed stem. I have seen a few that were slightly pinched when assembled, but hadn't breached the whole tube surface. Then a little low on air and the pinched tube tears in the pinched spot.

For me (just my opinion from what I have seen and heard) I would say the #1 issue has been low tire pressure from not checking often enough then taxiway debris. Use good tires like the Monster treads with extra rubber and Leak Guard tubes and taxiway debris goes away.

 

If you use the cheap standard tubes that will leak down and only use 29 psi as in the book then once it looses 5-10 psi your in for a flat. By using the better thicker tubes (i.e. Michelin Air Stops or Leak Guard tubes) and using 35 psi your leak down and loss of 5 psi isn't near as likely to put you in a bad spot. I see too many tires in for annual with pressures of 15-20 psi in the front and 25 for the mains.

[FastEddieB]

 

 

The issue from my perspective is much too high a failure rate in the CTLS / LSA aircraft inner tubes.

 

It seems to me that the LSA aircraft tubes are cheap and deficiently designed. They DON'T do the job. The tires are fine .... they don't fail .... it's the tubes that fail.

 

I would point out again that a new CTLS costs $160,000+, 10x what an average car costs, and it's a big shame to have unworthy tire tubes on such an expensive vehicle.

 

For perspective...

 

...Cirrus owners have the same problems, in a plane that is now close to $800k.

 

Those pilots seem to lean to Michelin AirStop tubes. The Goodyear tubes seem to be very sketchy in quality and prone to failure.

[Roger Lee]

Hi Steven,

 

many MFG's in an industry don't always know what's out there and some times the end user ends up knowing more in a specific area like our tires and tubes. As a retired MFG I will also say that sometimes you have to draw a line at how much you're going to put into something for the end user or it will cost twice as much and you could never sell the product.

As an example I used to Mfg dive compressors and used Honda engines. A couple of guys wanted me to make the engines out of stainless steel. So my product would have gone from a total cost of $2500 to well over $10K. Would it have been better , yes, but I would never have sold a single unit. So cost control in Mfg does come into play.

 

That said I'm with you on the tire issue. For me I would like to have seen all 6.00-6 tires for the mains and 4.00-6 front tires all with heavy duty tubes because they tend to be better than the small tires for performance and reliability and you have a much better selection of quality choice, but adding these also cuts into our usable weight. There are darn few places that have or Mfg 4.00-4 and 4.00-6 tires and if demand drops they could discontinue and put many in a bind.

[Dan Kent]

Are there any tires available for the CTLS that don't require an inner tube ? It sounds like the slippage between the tube and tire is often the cause of a tube failure, particularly at the valve stem which gets increasing sideways pressure. That was the point of failure in my first flat, but I don't know about the others.

 

FWIW my plane uses tubeless tires on the mains (haven't checked the nose wheel). The mechanic did use a tire dressing when he changed my tires, but these are 15x6.00x6" tires. There is an "o" ring in the middle of the wheel (that he also put the tire dressing on) and then mated the 2 halves and put air into them (I had about 130 hours and 200+ landings on the original OEM tires). I was doing my flight training with the originals and obviously had some ugly landings on them but never had any issue with the tires. I wasn't sure they could make another year, so I asked him to change them out at my annual.

 

I check the air pressure about once a month but my wheel pants have a hole in them to line the stemsand an extender was provided to screw into the stem, so it only take probably 15 minutes to check and add air each month.

 

I think this company made my wheels as they look identical except mine are plain aluminum. BTW I contacted this company and they now have a Chicago office.

 

Here's their French brochure, and here's their Chicago email address: us.sales@beringer-aero-usa.com

catPlaneUS.pdf

[FastEddieB]

As I mentioned elsewhere, the Sky Arrow now comes with Beringer's instead of Marc Ignego's:

 

 

 

Did not realize they might be tubeless.

[Dan Kent]

Here's the 2013 catalogue.

catPlaneUS 2013.pdf

[Steven]

The failures I have seen usually come from runway or taxiway debris or low tire pressure resulting in a stressed stem. I have seen a few that were slightly pinched when assembled, but hadn't breached the whole tube surface. Then a little low on air and the pinched tube tears in the pinched spot.

For me (just my opinion from what I have seen and heard) I would say the #1 issue has been low tire pressure from not checking often enough then taxiway debris. Use good tires like the Monster treads with extra rubber and Leak Guard tubes and taxiway debris goes away.

 

If you use the cheap standard tubes that will leak down and only use 29 psi as in the book then once it looses 5-10 psi your in for a flat. By using the better thicker tubes (i.e. Michelin Air Stops or Leak Guard tubes) and using 35 psi your leak down and loss of 5 psi isn't near as likely to put you in a bad spot. I see too many tires in for annual with pressures of 15-20 psi in the front and 25 for the mains.

 

Thanks Roger - I'll be using the leak guard tubes and will pump the new tires to 35 lbs and check the air pressure regularly. Hopefully that will solve the problem.

[Roger Lee]

I think you'll be happy doing it this way and the ugly dreams of flat tires on the runway will pass.

[opticsguy]

quick tip from a guy who has changed many a racing bicycle tire.

 

After installing a new tube, or re-inflating a wheel that has gone flat over a year of non-use, pump the tire up to about 5 psi, let the air out. Do it again. Then go to half of the recommended pressure and let the air out again. Then pump up to normal pressure.

 

This helps remove the kinks/folds and seats the tube the way it wants to be under pressure. Sometimes you can hear the tube move when letting the air out. That is stress you don't want under high pressure.

[Tom Baker]

Those pressures will be fine with tundra tires.

[Roger Lee]

Tom's right that 35 is okay with the tundra (6.00-6) tires or any of the FD tires. FD had a SL out years ago that gave permission up to 35 psi because that is where they did their drop test. 35 works in the tundra, but because the tundra can carry more weight, at least for me, it tends to be a stiff ride. That's why I usually fill customer 6.00-6's and mine to about 27 psi. ( you may prefer a different pressure) The nice thing about the larger wheels is since they can carry more weight and tend to be a little stiffer they can get quite low in pressure before the tire wants to turn on the wheel. I would wager a bet that on a Matco main wheel and a tundra tire could see at least 10 psi before I started to sweat. (don't try and go there just for fun) Many have even said when they had a flat it was almost like it wasn't there. Same thing with the 4.00-6 8 plys. They are so stiff flats aren't usually an issue during a landing. The 4.00-6 4 or 6 ply will crush down and want to pull harder to that flat side. Personally I think FD could have cut cost and inventory by only using the 6.00-6 in the US. Other countries with the 450 Kg limit would have added too much weight since FD was trying to shave every little pound.

That's one thing is is very different with our planes verses much heavier GA aircraft. If they get a flat there is enough weight to crush the tire to the rim and cause issues (damage and control). Our planes are so light that many times the wheel never touches the ground and have seen a few CT's taxi in on flat tires.

 

 

My preference (yours my differ) for pressures are small tire 4.00-4 or 4.00-6 6 ply is 35 psi.

Tundra 6.00-6 mains 27 psi and the front 4.00-6 is 35 psi like the mains on the smaller wheeled CT.

 

Pick your poison (psi)

[Doug G.]

Another little old time gas station trick is to inflate the tire partially and bounce it a few times on the floor rotating it each time to even out the inner tube, then inflate it the rest of the way.