Frequent Inner Tube Failures

[paul m]

I am looking for recommendations on equipment I should have to check tire pressure and top up the psi. I thought I remember a thread on this topic but can't find it. I have tundra tires and I'm looking for easy solutions that don't require removing or cutting the fairing. Can you recommend stuff like tire pressure gauges, flexible hoses and fittings, electric vs foot pump etc vs air compressor, etc? Thanks in advance

[Roger Lee]

Hi Paul,

 

Best to cut the wheel pant. Any thing else is a pain. There is an LOA and it only takes a couple of minutes to do both. Nothing really works as far as tools.

 

If you want some verbal help just give me a call.

[paul m]

Thanks Roger. How big a pump do I need? Wlll a portable 12v one be sufficient? or a foot pump? I'd rather not buy an air compressor.

[FlyingMonkey]

Paul, I found a 12V pump sufficient, but very slow to get pressure in the tires. I went to an 120V AC-powered pump from Pep Boys in the hangar and it pumps up very quickly, I have to watch carefully to not over inflate.

[Anticept]

A bike pump is more than enough, but it will take a while to pump up a tire. Upside, you can keep it in an emergency kit if you end up with a flat tire off field.

 

Also, here's a good link that people should read when it comes to tires. There's a huge amount of misinformation about them out there; for example, weather checking, aka dry rot, is actually acceptable until it becomes severe.

 

Page 9-9, paragraph 9-13 onwards

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/list/AC%2043.13-1B/$FILE/Chapter%2009-10.pdf

[S3flyer]

I've used a bike pump for years and only takes a few pumps to top off the tire.

[Anticept]

I've used a bike pump for years and only takes a few pumps to top off the tire.

 

I meant from zero

[paul m]

Do you need any special fittings to get the end of a typical bike pump under the fairing onto the nozzle? Do you suggest an inline gauge?

[S3flyer]

I use this for both my road bike and plane: http://www.performancebike.com/bikes/Product_10052_10551_1147593_-1_400165__400165

[paul m]

Thanks Dave

[Anticept]

I use tundras and we were having the same problem with tubes popping. 35 was wearing the tubes too fast. We found 32 to be a nice balance for a flight school environment, and our friends at airtime aviation do the same. Personally i would recommend 32.

[Roger Lee]

Hey guys,

 

30-35 psi for the smaller 4.00-6 & 4.00-4 tires are okay because they support around 800 lbs each, but the 6.00-6 (tundra) at anything over 30 is too much. Even 30 psi in the 6.00-6 is a pretty stiff tire. Those tires can support over 1700 lbs. each. Most of us only use around 24-28 psi for tundra tires. I personally use 26 and I fly MUCH heavier than either of you. Pressured up that high with these heavy tires gives no cushion on poor landings because the tires are so stiff. They won't wear or track as well either. Try a lower pressure and I think you'll be happier.

[Anticept]

Hi Roger!

 

We had three wheel rims split filling at 29 psi, a cracked rim developing when it was caught, and multiple flat tires, one of which led to an accident, all over a two year period. We've always been using 6.00-6 @ 29 psi. When we started using 32 psi over a year ago, these problems stopped. Also, I run a flight school, we've had light loads, max gross loads, and everything in between, landing in grass strips and asphalt. She's got 2021 hours on her now. I don't think you can claim you've flown heavier than me without raising eyebrows (and even then I suspect that she's flown over max gross a couple times too ) .

 

I am open to suggestions as to the causes, but we've been very successful with 32.

[Doug G.]

$39 -20% Harbor Freight pancake compressor.

[Anticept]

GA aircraft tires should still be inflated to the manual or LOA description (see LOA section for the authorization for higher inflation), even during the winter. A/C tires aren't in constant use, and don't heat up like car tires do.

[Roger Lee]

Hi Anticept,

 

1465-1475

 

The only wheels I have seen split is the cheaper Marc Engegno Italian wheels. Do you have these wheels?

They are stamped out thin aluminum. Too much pressure, too little pressure with too many hard and or side loads will crack these wheels. My bet is more side loading than you really know. I have seen 3 and know of 3-4 others. The metal is so thin that tire pressure alone causes these to flex. I discovered this back in 2007. If you want to start keeping wheels from cracking go to the Matco's. Cut out of solid stock and much heavier aluminum. Then a little lower pressure or a little higher pressure with a side load during a landing won't be as troublesome.

Install the Matco's, with Leakguard tubes and 6.00-6 Monster treads (tread almost 3 times thicker) and you'll never have to worry because they'll be darn near bullet proof. Install the Matco front wheel and this will help eliminate most of the tire slippage unless it gets excessively low and then that's the owners fault.

 

The reason many tires go flat especially the front one is from too low a pressure that allows the tire to turn on the wheel and this pulls the stem. This happens during taxi more often than not or when the tire touches down and goes from zero to mach 2 in a second.

[FredG]

I run between 30 and 32 psi in my 6.00x6 tundra tires (I fill to 32 psi and when down to 30 I pump them back to 32). I currently have Desser Monster tires and Leakguard tubes.

 

I don't know how anyone can say that "Most of us only use around 24-28 psi for tundra tires" without actually doing a survey of tundra tire owners. Has that been done? Roger, is that "most of us" in Arizona or nationally?

 

In 1900 landings on my 2006 CTsw, I have had one main gear OEM Marc wheel split (partial circumference split, didn't affect taxi, noticed on routine inspection). I have experienced no flats due to tube or tire failure. My plane tracks fine at 32 psi and my Desser Monster tires are wearing very slowly.

 

Is it possible that 28 psi would lessen the load on the wheel (and have prevented the wheel failure)? Maybe. Would 28 psi increase risk of tube failure? Maybe.

 

Your mileage may vary.

[Roger Lee]

All of the 6.00-6 wheels that come through here are around 26 psi. Some a pound or two higher some a pound or two lower. I haven't seen anyone come through here with 30 psi or above in a 6.00--6. It's because they were designed to handle so much more weight than the 4.00-6 that they don't need it. On a hard landing it will also have a little give and help the suspension. I have had my monster treads like this for 6 years and others here as well. I recommend to everyone that calls from all over the world with a CT and 6.00-6 that they try around 26 +/-psi. These tires can support the plane all the way down to 8-10 psi without any issues because I have seen a few come in for inspection that low and they can support that weight because they were designed to support 1700 plus lbs for each tire so our weight spread out over all three tires is no big deal.Technically one tire can support our gross weight and then some. So the side walls are stiff enough to handle all that weight so that should be an indicator you don't need a lot of pressure when spread out over multiple tires. I'm not saying you can't use 30+ psi in the 6.00-6 it just isn't necessary and gives in to a hard ride and less help to the suspension since CTSW have a little weaker leg to start with. CTLS 's still smash and crack gear legs too so a little help may make the difference between no problem or waiting months for a new leg.

i don't always believe what an MFG says and follow it blindly it has to have some science and common sense behind it. So yes you can put whatever you want in the tires even 50 psi or 15 psi, but getting the most out of the tire in wear, traction and suspension helps.

Low pressure in a 6.00-6 is far less likely to spin a tire on a wheel than the 4.00-6 and even more so verses the 4.00-4 nose wheel. 6.00-6 tires seem to be more popular out west for some reason so I get to see lots of them during the year and I have been using Monster tread tires from Desser long before any CT ever saw one. I used them on my last plane too.

 

With my Matco wheels (less flex and I have never seen a Matco split only the Marc wheels) , Monster tread 6.00-6 6 ply tires and Leakguard tubes I only put in 1-2 psi of air every 6 months.

 

While we are discussing and debating, go out and try different pressures. I did this back in 2007 from 16 psi up to 32 psi and settled in on 26. It won't hurt to experiment a little.

[Roger Lee]

Hi Fred,

 

Do an experiment then get back to us. Drop your pressure to 26-27 psi for a couple of months and see what you think. It won't cause any tube issues. It will also help put a little more tread on the ground so the guys that are wearing on the outside edges from too much camber may get some help.

[Anticept]

Hi roger!

 

I have thought about switching to matcos, because the italian wheels really are so damn thin. Here's the accident report: http://dms.ntsb.gov/aviation/AccidentReports/cby350u5a0feawaqkqokk5451/B11072013120000.pdf

 

Matco conversion runs about a thousand right?

[Roger Lee]

Hi Anticept,

 

Yes on the price. A little less for parts, but then you have labor which should be about 2.5-4 hrs depending if it s an SW or LS and how fast the mechanic is. All the split rims have been the Marc wheels and the wheel diameter changes with pressure which causes the disc to bind on the pins.

[Jim]

I have Marc wheels, Airstop tubes, monster retreads and 26-27 psi. About a thousand landings, over half student landings with zero issues.

[FredG]

Roger, fair enough. I will drop to 30 psi for a while and then to 28 psi and report on my experience.

 

Also, does the wheel diameter change with pressure or the wheel width? Hard to see how pressure would affect the diameter to any appreciable degree. I can see, given their construction, how pressure might affect their width as well as the angle of the pins on which the disc floats.

[Anticept]

Hi Anticept,

 

Yes on the price. A little less for parts, but then you have labor which should be about 2.5-4 hrs depending if it s an SW or LS and how fast the mechanic is. All the split rims have been the Marc wheels and the wheel diameter changes with pressure which causes the disc to bind on the pins.

 

I am the mechanic

[Roger Lee]

Hi Anticept,

 

Sounds like labor is free. If you do decide to go that way give me a call and I'll give you some tips and tricks.

 

Hi Fred,

 

Try 26-27 first. That's what we use.

 

Because of the thin stamped metal, pressure seems to affect diameter and width. I don't have any numbers and don't know which is worse because it has been 6 years, but I have played with it on a bench and added and reduced air pressure and the disc is affected.