[N427EF]

A bit of background:
I have never had a flat tire on an airplane and this one hit me by surprise.
Last condition inspection in January of this year, I installed a new nose wheel tire and a new tube. At almost 700 hours of service without needing anything not even air, I decided to be pro active and replace something that wasn't broken.
About 50 hours into the new tire, we taxied back after a lunch fly out and came to rest in front of my hangar with a completely flat front tire.
In order to push the RV-10 into the hangar, I had to inflate it but we barely made it past the hangar door before it was completely flat again.
Removing the wheel and tire revealed a cut as seen in the picture and I cannot figure out how this happened. I do not make short cuts, the tire and tube was properly installed with plenty of talcum powder and the location of the cut does not appear to be the result of a pinch or other installation error. What have I missed here?? the tube and tire have been sitting in my hangar for at least a couple of years. The only thing I can think of is the folded tube aging and suffering heat damage. Is this a possible explanation?
The tubes are whatever Van's sells along with the tire.

 

[Janekom]

Very strange. I cannot see any folding of any sorts.

What comes to mind is that maybe you have accidentally cut the the tube when you have opened the plastic bag? Long shot

Also depending on it's age, it can be a spot where it has perished.

Where did you keep it in your hangar? Someone has taught me that tires and tubes should be stored in a dark place where they cannot get any light or sunlight. A quick google search points to this as well.

 

[gasman]

Looks like you got an amazing tube the first time, and a dud the second time.
I would say you are even up with us that need to add air every 6 months....

 

[N427EF]

I am guilty of storing this tube/tire set for too long and failing to inflate it a bit as recommended.
The tube was stored in a box in its original packaging (folded) since 2019.
The hangar of course gets as hot as a toaster oven in summer and even in dark storage could develop the beginning of a cut along the fold lines. After a year of use the folds are no longer visible but it seems reasonable to assume.

I don't use knifes or other tools to open tube bags, just fingernails.

Anyway, thanks for the suggestions I was hoping someone would see something "obvious" that I may have missed.

 

[vasrv7a]

I am guilty of storing this tube/tire set for too long and failing to inflate it a bit as recommended.
The tube was stored in a box in its original packaging (folded) since 2019.
The hangar of course gets as hot as a toaster oven in summer and even in dark storage could develop the beginning of a cut along the fold lines. After a year of use the folds are no longer visible but it seems reasonable to assume.

I don't use knifes or other tools to open tube bags, just fingernails.

Anyway, thanks for the suggestions I was hoping someone would see something "obvious" that I may have missed.

I might suggest one other direction with respect to the nose wheel... If there is an available Beringer tubeless nose wheel for the RV-10 I would recommend switching to a tubeless tire. About 8 years ago I switched my RV-7A nose wheel to a Beringer tubeless nose wheel and tire... Best thing I ever did, I no longer have to worry about or deal with tube damage or tire deflation. A pricer solution... but seems to be much more reliable. Good luck.

 

[N427EF]

Thank you for the suggestion and installing a tubless Beringer wheel has crossed my mind.
The reason for this thread is to find out how a tube can split along the side as indicated in the picture? The tire appears to be in excellent shape, tire inflation may have been a bit low, possibly but I cannot think of any other cause for this slit other than the ones mentioned.
We have also taken a closer look at the rest of the tube and found a host of similar cracks.
I did not expect a lot of " traction on this thread " kind of a boring subject but nevertheless, an answer to the problem could easily save someone else's day.
I am considering sending it back to Michelin for a close up look.
Not looking for money or refunds, just an explanation so this sort of thing can be avoided in the future.

 

[lawrence]

flat tire

"a closer look at the rest of the tube and found a host of similar cracks"
probably the compound, to make the tube, was changed at some time during its production run. a common practice by tire manufacturer's.
do not buy same make and model again.
the tubeless tire solution mentioned
may be best solution.a tubeless tire will hold air long after it develops surface cracks. my experince,yours may vary.

 

[Desert Rat]

I believe you, but when you zoom in on that picture, it sure looks like a puncture that then split. See how it has a jagged edge in the middle of the split? Are you absolutely sure you don't have. corresponding hole in the tire, like from a piece of safety wire or something?

It will be interesting to hear if you get to the root cause.

 

[AlexPeterson]

SNIP
The reason for this thread is to find out how a tube can split along the side as indicated in the picture? SNIP

The failure looks exactly like what many have seen on the nosewheel tubes on 6-9's, including the 2 or 3 flats I had.

My own theory (and I had 2 or 3 flats in the first year or two) is that the repeated flexing of the tire/tube wall causes some cumulative relative sliding motion between the two. This stretches the tube beyond its limit in certain locations. I do not have a theory of the mechanism of this, it is based only on observation.

I know that you used talc, but put a crazy amount of it in, spreading it on both the tire and tube.

 

[Norman CYYJ]

Inspect the inside of the tire very carefully. I had a similar flat a few years ago and the cause was a cut in the tube caused by a piece of cord protruding from the tire. The tire was not properly inspected. Could be the same problem. In my case there was around 230 hours on the tire when the cord finally cut through the tube.

 

[vasrv7a]

Thank you for the suggestion and installing a tubless Beringer wheel has crossed my mind.
The reason for this thread is to find out how a tube can split along the side as indicated in the picture? The tire appears to be in excellent shape, tire inflation may have been a bit low, possibly but I cannot think of any other cause for this slit other than the ones mentioned.
We have also taken a closer look at the rest of the tube and found a host of similar cracks.
I did not expect a lot of " traction on this thread " kind of a boring subject but nevertheless, an answer to the problem could easily save someone else's day.
I am considering sending it back to Michelin for a close up look.
Not looking for money or refunds, just an explanation so this sort of thing can be avoided in the future.

I understand... keep in mind that from what I've learned about general aviation tires over the 45+ years that I've been flying... Flat aircraft tires are generally and almost exclusively the result of tube failure, not problem tires or tire/tube punctures. Punctures from debris on taxiways and runways are rare, and regardless of the reason for your tube failure, you can never be sure of what's causing a failure... folds in the tube, age, abrasion from something inside the tire, etc. and therefore ongoing vigilance will always be required. I chose to eliminate the possibility of a nose wheel tube failure by switching to tubeless. And if the cost to change the main tires of my RV-7A wasn't so prohibitive, I would change my main tires to tubeless.

 

[N427EF]

Thanks

I appreciate all the suggestions and insights.

I will take another very close look at the tire.

The Beringer tubeless wheel looks good and I am giving it some thought.
Of course I already have a new tube and tire on order.
My axle is a Matco with lockable spacer and shimmy hasn't been a common issue and neither have I ever had a flat tire in 40 plus years of flying.
Time to rethink some things.

 

[lr172]

I see what appears to be a defect just up from the center of the tear on right side. Guessing this weakened the rubber and eventually caused the tear. Unclear if this is a mfg defect or damage.

 

[N427EF]

Manufacturing defect?

I promised an update and here is what we found.
First off, I thoroughly inspected the tire, both visually and with a bore scope.
The visual inspection included a fine thread cloth used to clean optics and one that surely would have torn had the inside of the tire had any sort of roughness
or sharp object poking out toward the inside. The tire seems to be in good shape.
The tube however, under very close examination reveals these pokemarks as seen in the picture. They are more like chunks missing and they are all around the sides about the same elevation as the tear that cause the flat.
What do you think?
I am considering sending this back to the manufacturer.
As an aside, I ordered a tube from Vans as they had shown "in stock" but have yet to receive a shipping/tracking email, that was almost 2 weeks ago.
Being short on patience, I ordered another from Spruce that should arrive this week. I'll keep Vans as a spare when it does arrive. Those 2 orders totaled three hundred fifty dollars worth of inner tubes.

 

[rvbuilder2002]

Tube damage in the sidewall area is usually cause by insufficient lubrication and/or under inflation.

Run the tire low on air and lack of lubrication (talc) becomes a much more serious issue.

A lot of people think they use a lot of talc but statistics indicate otherwise.

When I install a new tire and tube I keep rotating to coat every square inch inside and then keep adding talc until no more will stick anywhere on the interior surface.... then shake out the excess.

Then I lightly inflate the tube (just enough to get it to take its full shape, but not enough to stretch it dimensionally) and then coat the entire outside of the tube until no more will stick.

Then I de-air the tube and insert it into the tire.

If I do it this way, when I remove the tube from a tire that is being replaced, the surface of the tube still has talc on it.

Lots of talc wont prevent pinch damage on severely under inflated tires though (this seems particularly true on the small sized nose wheel tire).... become familiar with what a properly inflated nose tire looks like and check it at every pre-flight. If you don't know what to look for, then check the pressure regularly.

 

[AlexPeterson]

Tube damage in the sidewall area is usually cause by insufficient lubrication and/or under inflation.

Run the tire low on air and lack of lubrication (talc) becomes a much more serious issue.

A lot of people think they use a lot of talc but statistics indicate otherwise.

When I install a new tire and tube I keep rotating to coat every square inch inside and then keep adding talc until no more will stick anywhere on the interior surface.... then shake out the excess.

Then I lightly inflate the tube (just enough to get it to take its full shape, but not enough to stretch it dimensionally) and then coat the entire outside of the tube until no more will stick.

Then I de-air the tube and insert it into the tire.

If I do it this way, when I remove the tube from a tire that is being replaced, the surface of the tube still has talc on it.

Lots of talc wont prevent pinch damage on severely under inflated tires though (this seems particularly true on the small sized nose wheel tire).... become familiar with what a properly inflated nose tire looks like and check it at every pre-flight. If you don't know what to look for, then check the pressure regularly.

Scott nails it here. Everything will be white with talc when you get done. And, as he wrote, it will still be evident when you disassemble a year or three later.

 

[lr172]

I promised an update and here is what we found.
First off, I thoroughly inspected the tire, both visually and with a bore scope.
The visual inspection included a fine thread cloth used to clean optics and one that surely would have torn had the inside of the tire had any sort of roughness
or sharp object poking out toward the inside. The tire seems to be in good shape.
The tube however, under very close examination reveals these pokemarks as seen in the picture. They are more like chunks missing and they are all around the sides about the same elevation as the tear that cause the flat.
What do you think?
I am considering sending this back to the manufacturer.
As an aside, I ordered a tube from Vans as they had shown "in stock" but have yet to receive a shipping/tracking email, that was almost 2 weeks ago.
Being short on patience, I ordered another from Spruce that should arrive this week. I'll keep Vans as a spare when it does arrive. Those 2 orders totaled three hundred fifty dollars worth of inner tubes.

Those are manufacturing defects. based upon the jagged shape of the depression, it appears that debris of some sort was stuck to the mold when they made that tube. The depression leaves the rubber very thin in that spot and can't handle the pressure and movement. Probably last run of the day on Friday. just like engine building, cleanliness counts. If you go back to original pic, you can see the depression on the right side at the center of the tear.

 

[jliltd]

I didn't catch the make and model of the damaged inner tube. Should I hazard a guess that it is a Leak Guard?