Tyre inner tubes

[BigEndBob]

What the hell goes on with tyre inner tubes. Had now about five deflations and flats in 12 months, club aircraft.
This would be on a Piper Tomahawk 5 inch wheels.
Both mains and nose.
Even had at least 2-3 on Warrior.
Are there some bad brands out there or dodgy batches going around.
If it was one bad wheel i could understand something wrong with that wheel.

[Maoraigh1]

Things on the surface? E.G. wire from brushing a hard runway in winter. It's removed by a magnet, but bits might remain at edge of grass, if light aircraft taxi onto grass.

[visibility3miles]

I’m told that the inner tube in the tire/tyre in the nose gear can rot out because the front tire gets such little impact and abrasion relative to the mains that it can get past its sell date since the nose wheel doesn’t get changed out as often as the mains.

I also remember being scolded by my flight instructor, when learning to fly, to not to turn the nose wheel unless you were moving, as that can scrub off some of the rubber at a single spot and reduce its useful life.
————
I landed at an airport once, enjoyed the local area with friends, then returned to find a flat nose wheel. Fortunately, there was a an FBO able to do repairs. They pumped up the front tire, only to watch it go flat again fifteen minutes later. They were able to replace the inner tube, or maybe the front tire too. I forget which, as it was a club plane, so I didn’t have to pay for it out of pocket.

I do know if I had it pumped up then took off immediately, it would have been flat again before I landed, which would have pushed my skills beyond what I had any interest in pursuing. My friends thought it was part of the adventure, especially the part where the mechanics leaned on the tail to lift the nose off the ground so the could repair the flat.

I have no idea why the mains would go flat. How long has it been since they underwent maintenace?

[BigEndBob]

Front might be 5 months since replace. Nothing in the tread, nearly new tyre.
No tyre has ever been found to have been damaged,
They just deflate for no good reason, then tube is ruined.
Sometimes i leave on Sunday, come back to work Tuesday, flat.
Most go flat just after turning off landing. This last tyre i checked pressure 3 days ago. Set at 38psi.
But have seen table that suggested as high as 50 psi.

[visibility3miles]

When I was in elementary school, some jerks used to let the air out of my bicycle tires on purpose just to be mean.

Seems highly unlikely in an aviation context, but maybe video surveillance wouldn’t be a bad idea.

Get in touch with the manufacturer and see if they have any ideas.

[BigEndBob]

When I was in elementary school, some jerks used to let the air out of my bicycle tires on purpose just to be mean.

Seems highly unlikely in an aviation context, but maybe video surveillance wouldn’t be a bad idea.

Get in touch with the manufacturer and see if they have any ideas.
Well that's my next port of call. I need to find what brands/supplier maintenance have been using for inner tubes.
It's getting expensive over a grand in 12 months on tyres/tubes plus fitting.

[Fl1ingfrog]

I’m told that the tire/tyre in the nose gear can rot out because the front tire gets such little impact relative to the mains

I wish that was true, aircraft tyres rarely last long enough to rot. Unfortunately the nose wheel takes a hammering at most flying clubs/schools and the nosewheel tyre changes and undercarriage repairs are the witness.

They just deflate for no good reason, then tube is ruined. Most go flat just after turning off landing.

Poor cross-wind technique and sideways landing owing to parallax are both guilty as well as from landing too fast. Tyres are required to go from a zero speed to a speed that is equal to that of most vehicle highway cruise speeds but in an instant. Operators from grass airfields report much better life from tyres in comparison to tarmac operations. Unnecessary and over zealous braking on grass will bite you but on tarmac it can be the all too common technique, especially when in order to take the early turnoff.

Directly steered nose wheels of the Piper range are a problem because the nose wheel can be aligned sideways from rudder input during the touchdown even if for no aerodynamic reason. The Tomahawks is infamous owing to this problem. The nosewheel assembly is attached to the forward section of the engine frame and requires regular expensive repairs especially those used for training. The sideways position of the nosewheel isn't confined to the landing but also the take-off. The Tomahawk requires quite a high speed before the high tailplane is capable of lifting the nosewheel weight. During the long period whilst the necessary speed is gained the tyre will be scuffing throughout a crosswind take-off.

[BFSGrad]

No tyre has ever been found to have been damaged,
They just deflate for no good reason, then tube is ruined.
What is the failure mode of the tube? Puncture? Faulty valve?

[visibility3miles]

I was taught to bank the plane into the landing, so the upwind wing is low and the nose wheel and plane is pointed straight down the runway.

It does mean cross controls with rudder pushed one way and ailerons the other, which may be a no-no in some circles, but if done just before touchdown at low speed it keeps you pointed straight down the runway.

One main touches down first, but the plane isn’t at an angle to the runway when you touch down.

[visibility3miles]

Directly steered nose wheels of the Piper range are a problem because the nose wheel can be aligned sideways on touchdown but for no aerodynamic reason. The Tomahawks is infamous owing to this problem. The nosewheel assembly is attached to the forward section of the engine frame and requires regular expensive repairs to those used for training .

Sounds like a design flaw. The plane where I had the front tire go flat was a Piper Warrior II.

Perhaps a better designed cowling would help keep the nose wheel better oriented upon landing???

It was a club plane, but you had to be a fully certified pilot to join. No students, and most people flew the Cessnas. I learned to fly elsewhere on Tomahawks, then Warriors, so I was one of the few that used the Warrior on a regular basis.

I think I knew how to make decent landings by then…

P.S., I learned to fly in California, where planes bake in the sun at least nine or ten months out of twelve.

[Bend alot]

What the hell goes on with tyre inner tubes. Had now about five deflations and flats in 12 months, club aircraft.
This would be on a Piper Tomahawk 5 inch wheels.
Both mains and nose.
Even had at least 2-3 on Warrior.
Are there some bad brands out there or dodgy batches going around.
If it was one bad wheel i could understand something wrong with that wheel.


If you do not use a good dose of talcum or baby powder on the tube and in the tyre - expect deflations.

[megan]

From GoodyearIt is recommended that tubes not be reused; they can grow as much as 25% in service. Reusing them can result in folded, pinched tubes which can fail or create an imbalance. Ensure that any manufacturing stickers on the tire innerliner are removed to prevent damage to the tube.

Michelin advice on tube installation.Inflate to the recommended pressure, deflate, then reinflate to assure a proper fit of the tube inside the tire. This procedure helps remove any wrinkles in the tube and helps prevent pinching the tube under the toe of the bead. it helps eliminate the possibility of one section of the tube stretching more than the rest and thinning out in that area. Further, it assists in the removal of air that might be trapped between the inner tube and the tire. let stand for 12-24 hours to compensate for tire growth and to allow any air trapped between the tube and the tire to escape. After placing in service, check pressure before each flight and for several days, adjusting pressure as necessary, until the tire stabilizes.Both include Before installing tube, dust the tube and inside of tire with tire talc or soapstone.

[JuicyLucy]

Get the club to replace all the inner tubes!
I had a similar problem some years ago on my aircraft - random deflations.
Turned out to be all the inner tubes had been on for about 20 years, not replaced when the tyres had been.
All had minor leaks which only showed up now and again. Changed the lot and not had a problem since…..

[B2N2]

Is it the same person or the same shop replacing the tubes? :suspect:

[BigEndBob]

Is it the same person or the same shop replacing the tubes? :suspect:
Well yes, i'm going to watch what they do next time, perhaps i go armed with a packet of talc and ask them to give the tubes a liberal coating.
I don't remember seeing a tyre with any talc marks on. Might make it easier for the creep mark paint to stay on.
Something odd is going on.

Most times tubes can't be checked for leaks as they don't survive being taxied on flat, but i'm going to follow the fix on this tyre, see what goes on.

[BigEndBob]

Get the club to replace all the inner tubes!
I had a similar problem some years ago on my aircraft - random deflations.
Turned out to be all the inner tubes had been on for about 20 years, not replaced when the tyres had been.
All had minor leaks which only showed up now and again. Changed the lot and not had a problem since…..
All the tubes have been fitted last 12 months and new tyres.

[BigEndBob]

Sounds like a design flaw. The plane where I had the front tire go flat was a Piper Warrior II.

Perhaps a better designed cowling would help keep the nose wheel better oriented upon landing???

It was a club plane, but you had to be a fully certified pilot to join. No students, and most people flew the Cessnas. I learned to fly elsewhere on Tomahawks, then Warriors, so I was one of the few that used the Warrior on a regular basis.

I think I knew how to make decent landings by then…

P.S., I learned to fly in California, where planes bake in the sun at least nine or ten months out of twelve.
One problem with Tomahawks, no nose shimmy damper, just Piper penny pinching.

[MrAverage]

Bob!

We had exactly this problem about 3 years ago, as did other operators at our airfield (including our CAMO that had about 5 a/c at the time). All were eventually changed for expensive but top quality tubes and tyres, including our most fabulous Tomahawk (it really is exceptional).
Normal service was resumed instantly.

[xraydice]

What is the failure mode of the tube? Puncture? Faulty valve?
I would have this at the top of my list of suspects, Have had unexplained flats , a new valve and all good.

[stevef]

The yellow metal valve caps act as a secondary seal if the valves themselves are leaking. Plastic caps only keep the dust out.
I remember from a long time back that some cheap inner tubes weren't up to the job. I can't remember the country of origin.

[propnut]

Valve caps are designated "primary seal" in engineering exams

[stevef]

I'd be genuinely interested to see where that's written, propnut. There's nothing about it in the UK CAA Civil Aircraft Inspection Procedures. What they do state, is when tyres are being leak-checked after mounting on the wheels, the cap is not to be installed to allow the valve core serviceability to be proved. No mention of ever routinely checking the yellow 'primary' installed caps with leak detector spray. It would obviously be a waste of time if the valve core is working properly so how could it tested for serviceability? I've never seen caps being specifically called up for any maintenance other than general visual inspection. Considering some tyres are inflated to 200 psi it's hard to follow that a 'primary' seal wouldn't warrant any kind of function check ever.
This subject came up on Pprune about ten years ago and it turned into quite an entertaining thread.
See here: https://www.pprune.org/engineers-technicians/440309-valve-cap-missing.html?highlight=valve+cap+primary+seal

[jimjim1]

This subject came up on Pprune about ten years ago and it turned into quite an entertaining thread.
See here: https://www.pprune.org/engineers-technicians/440309-valve-cap-missing.html?highlight=valve+cap+primary+seal
Link didn't work for me. Quote it, presto, abracadabra, she goes good.

More edit: Now original post works for me too?!?!

[mossie1960]

MICHELIN AIRSTOP is what we have changed too after similar experiences on an RV-4 and RV-8 (so 5.00 x 5) wheels. It's a real PitA when there is a flat on these things - many screws to get the wheel pant off and if you try and drag it along with a flat it tends to damage the pant anyway.

We now bite the bullet and change the tube with every tyre change. This time (just done a tyre change) one of the tubes had been "welded" to the tyre at one spot. Carefull inspection makes me think that the tyre at some point had been locked (or scuffed - it is a taildragger :} ) and things got a bit hot..

You can feel the difference between the cheaper tubes and the Airstops. You do pay for it though, but we think it's worth the cost against the absolute b*ggeration of getting a flat.