Frequent Inner Tube Failures

[Steven]

I don't know whether it's bad luck, low quality inner tubes or their limited life expectancy, but I experienced my 3rd inner tube failure in 2 years upon landing at Westchester Airport Saturday evening. It came at an awkward time because the flat tire happened on my landing roll out and forced a large Jetblue passenger jet touching down about a minute behind me to go around from about 50 feet altitude as he neared the runway threshold. The main runway then had to be shut down for about 10 minutes as airport operations checked for tire or other debris (there was none - it was just a flat tire, not a blow out).

Airport operations then put a trolley under the flat tire and we walked the plane about 1/3 mile to its tie down.

No harm done, but I sure don't want to disrupt HPN airport operations again ! The landing was soft and good - only late in the roll out did the flat left main tire pull the aircraft to the left followed by the characteristic thump thump thump of a roll severely hobbled by a totally flat tire.

I did have some forewarning before flying out of Lake Placid - I had to request some air for the tire which appeared about 1/2 to 1 inch low. It looked fine after the mechanic brought it to 29 lbs, and I didn't give it another thought, attributing the low pressure to routine air loss. I vaguely recall experiencing a surprising right crosswind on my takeoff roll, so in hindsight, if memory serves, that may have been a rapidly softening left tire which then retained some limited pressure while in the air.

I need a proactive solution to avoid a recurrence of this problem - either accept that these tubes have a high rate of failure after a year of use and replace them at every annual inspection .... or find a high quality inner tube with a reliable long life expectancy. I don't understand why they fail with such limited mileage (perhaps 40 miles of taxiing per year ?), but the facts are the facts. The inner tube that just failed had been replaced in a June 2012 servicing and inspection. (the first 2 failures occurred while in tie down - harmless, but still a nuisance - at least those tubes were 3 to 4 year old originals).

I've ordered an Aero Classic tire and double thickness inner tube from Desser, express delivery. Maybe the double thickness will help ? Already had a spare tube in the plane, but not a tire which may have been damaged.

Are these any good ?

http://www.desser.com/store/products/400%252d6-%2813%7B47%7D500%252d6%29-AERO-CLASSIC-%22LEAKGUARD%22-BUTYL-AIRCRAFT-GRADE-INNER-TUBE.html

http://www.desser.com/store/products/400%252d6-6-PLY-AERO-CLASSIC-TIRE-TT%7B47%7DTUBELESS-%2814-X-4%29.html

Any other recommendations or proactive solutions ? Are the frequency of my inner tube failures normal and to be expected ? Car tires rarely fail in my experience even with 500 to 1000 times the mileage of my aircraft tires. What's the problem with my CTLS tubes and tires ??? It's a shame to have a $160,000 aircraft with unworthy tires.

[Roger Lee]

Hi Steven,

 

Make sure you use those heavy duty "Leak Guard" tubes from Desser you had posted. Keep 35 psi in the tires and not 29 psi. 35 psi is approved. If you use 29 psi and the pressure drops a little then when that tire grabs the runway at 100+ mph it will cause the tire to turn on the wheel and pull or tear the stem. I use 35 psi for all three tires for the guys with the small 4.00-6 tires. I use 35 psi in all front tires and if you have the 6.00-6 tires 25-27 works fairly well because they have a higher weight rating. Flats usually come from thorns or low tire pressure.

[FredG]

Steven, do you have Tundra option tires or standard tires?

[Steven]

I have standard tires ..... the ones referenced in my original post, except that now I'll go to the double thickness tubes.

[Steven]

Hi Steven,

 

Make sure you use those heavy duty "Leak Guard" tubes from Desser you had posted. Keep 35 psi in the tires and not 29 psi. 35 psi is approved. If you use 29 psi and the pressure drops a little then when that tire grabs the runway at 100+ mph it will cause the tire to turn on the wheel and pull or tear the stem. I use 35 psi for all three tires for the guys with the small 4.00-6 tires. I use 35 psi in all front tires and if you have the 6.00-6 tires 25-27 works fairly well because they have a higher weight rating. Flats usually come from thorns or low tire pressure.

 

Maybe too much tire talc ? Could excess talc powder cause slippage ? Or is the opposite true ?

[CT4ME]

Also, it's possible to pinch the tubes between the wheel halves, which can result in a slow leak or complete failure. Slow leak would lead to the low pressure situation Roger mentioned above, and a likely future problem.

tim

[Steven]

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.

[Jim Meade]

Who is landing at 100 mph?

FWIW, I have (suggested by another forum member) a fully assembled and inflated main and nose spare. When I'm going into a place I want no hassle and I have the space and weight, I throw one or both of them in.

[CT4ME]

'Like the idea of having those spares... But how am I going to explain to my wife I no longer have the capacity bring her along? :blink:

Tim

[Roger Lee]

Who is landing at 100 mph? Your tires are. They are small and spin hard on landing. Then if someone adds some braking on top of that and it is easy to slowly turn a tire over time.

 

Steven,

 

The only reasons people here have had flats is only one of three. Low tire pressure (most common by far), thorns and then as Tim stated a partially pinched tube that may not even start to leak for a month, but if the tube moves then it starts top leak.

 

If you just use the heavy duty Leak Guard tubes and keep the tire pressure up to 35 psi and don't let it get down in the 20's you won't have any issues. Talc won't have any bearing. It's the tire that turns which turns the tube which pulls on the stem or tears the tube because it was pinched just not leaking at that point.

 

Trust me on this one.

Just keep a closer eye on your tire pressures and the Leak Guard tubes will help stop as much air leak down over the cheap thinner tubes. I just checked my tires they only leak down 1 psi in 6 months, but I use the better materials.

[FredG]

Roger, yes, the tires are small and, yes, landing is hard on them. But, they don't land or roll at 100 mph unless the airplane is landing at 100 mph. I have no disagreement with your recommendations for tire maintenance.

[FastEddieB]

Who is landing at 100 mph? Your tires are.

 

I know there are pilots here, including Roger, who advocate landing with a bit of margin over the stall. Roger, I think, has settled into about 3-5k over the stall under normal conditions.

 

But 100 mph is 87k.

 

I'll repeat Jim's question...is anyone actually landing (touching down) at 87k? That would be about double the stall speed of a CT, even landing without flaps.

 

But Rogers's overall point is well taken - the tires are, in fact, pretty tiny for the speeds they must cope with. Still, the designers specified them as adequate for their function, so they should generally work without going flat on a regular basis.

 

I've had 3 total flats in just under 400 hours in my Sky Arrow (with 500x5 mains and standard tubes and a tiny wheelbarrow-type nosewheel):

 

1) Nealy flat main after being parked on grass overnight. Proximate cause may have been an oversized (600x6) tube installed at the factory, or a paper label left on the tube which abraded it, or a combination of the two.

 

2) Flat main while sitting in the hangar. Valve stem slightly loose on that one.

 

3) Flat nosewheel tire after normal (<45k) touchdown. Hole in tube from unknown cause.

 

I did literally just add about 5 lbs all around (to 35 lbs [from 29] main and 27 [from 22] nose), based on both Rogers's recommendation and the specs on the new Sky Arrow. Have not yet flown with the new pressures yet, but do not expect any subjective difference in feel - will report if there are any.

[Roger Lee]

None of this was my point. It was only hypothetical number to show tires turn from zero to whatever speed you want to pick in an instant and because of that are subject to turning on the wheel more so than other types of wheeled vehicles we use.. Air speed does not correlate equally to tire rotation speed. We are talking about tire speed and not air speed.

 

The tires we have are just fine for our application. The biggest problem across the board is getting pilots to check the tire pressure more often. Do that and use a good heavy duty tube and most all your problems should disappear. I know the cheap tubes are about $12 and the heavy duty tubes are close to $40, but in this case it's worth the extra money.

 

If checking your tire pressure is a PITA because of the wheel pants hanging too low and this makes you check them less often then trim the wheel pants up so it will make it easier.

[Ed Cesnalis]

If you land fast ( 100 mph ) then you would have enough energy to pull up steep to several hundred feet AGL, the reaction to your controls would be very precise and you wouldn't have to worry about a gust ruining your alignment or drifting you off of the runway.

 

So you took a lot of risk and it worked out you are on the runway at 100mph or whatever high speed.

 

Now you have to slow down, and soon your controls will be mushy but your energy will be high enough that a gust can ruin your alignment or drift you off of the runway. You took the risk but the payoff didn't last, you still had the wheels on the ground with mushy controls and enough lift being produced where a gust can change everything. In addition you have the risk of a flat at 100mph, ...etc.

[Roger Lee]

I'm sorry I ever used 100 mph.

 

Forget air speed here, think tire speed. this tire problem has nothing to do with air speed.

 

 

I'm not that much into math, but I'm sure one of you guys can tell us how fast a 4.00-6 tire turns when touching down at 50 knots.

[Ed Cesnalis]

The tire is traveling at 100mph and the math will give you its RPM.

[Tom Baker]

Roger, the tire tread would be covering the ground at a rate equal to ground speed. At 55 mile per hour our wheels would be turning about 1200 RPM if I did my math right, so they would go from zero RPM to 1200 RPM in a very short time at touch down.

[FastEddieB]

Roger, the tire tread would be covering the ground at a rate equal to ground speed. At 55 mile per hour our wheels would be turning about 1200 RPM if I did my math right, so they would go from zero RPM to 1200 RPM in a very short time at touch down.

 

I was about to post something similar.

 

The speed of the rubber touching the ground should be the groundspeed of the airplane, regardless of wheel diameter.

 

But, of course the smaller wheel will spin much faster, but that's a different matter.

 

Worth mentioning is that a wheel touching down at 100 mph has FOUR TIMES the kinetic energy of one touching down at 50 mph.

[Ed Cesnalis]

...Worth mentioning is that a wheel touching down at 100 mph has FOUR TIMES the kinetic energy of one touching down at 50 mph.

 

As well as the airplane its fastened too.

[FlyingMonkey]

I think the important take away here is that momentum and inertia on the tire/wheel interface during touchdown is very high, and if inflation is inadequate then the force can be enough to rotate the tire on the wheel, leading to slow or fast deflation.

[Roger Lee]

Thank You Andy.

[Ed Cesnalis]

I think the important take away here is that momentum and inertia on the tire/wheel interface during touchdown is very high, and if inflation is inadequate then the force can be enough to rotate the tire on the wheel, leading to slow or fast deflation.

 

For me an important point is that flats are common and high speed landing induced. A flat is an inconvenience but a loss of control from the fast landing / flat tire scenario is a serious, life and property threatening risk.

[sandpiper]

I have always carried a can of that tire inflator in a can. I have never had to use it in over 30 years of having one, but it will prevent you from being stranded unless you have a major tire problem.

 

Probably will need to junk the tube when you get home but it will get you out of an inconvenient situation.

[FlyingMonkey]

John, can't that fix-a-flat foam cause a serious tire imbalance as it cakes up unevenly inside the tube? I guess if you are only planning one more takeoff/landing cycle off the tube it doesn't matter much.

[sandpiper]

My original reason for carrying it was so I wouldn't get caught in remote Alaska areas where help might not be easily available and temperatures can be severe. Many of the landing areas were rough enough that you wouldn't feel any balance problems until in the air then a little brake would solve the problem. You might feel it back at home plate.

 

Anyway, never have had to use it so can't answer your question other than to say it is for emergencies.