Nose loses PSI faster than mains

ArrowFlyer86

ArrowFlyer86

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The Little Arrow That Could
I've been diligent about checking tire pressure ever since a nose-wheel tube went flat in September and stranded me overnight off home base.

In doing this I've noticed my brand new nose tire loses pressure faster than my mains.

While I might only lose 2psi in my mains between checks (LH/RH seem to always match), it's common I'll lose 8psi in my nose gear over the same time. The nose has a brand new tube installed in September, mains are same make but 1 year old.
Only idea was wondering if it was measurement error on my behalf... The smaller volume of the nose tire being more impacted by that couple seconds of HISSSSSS where it bleeds air out while I'm connecting/disconnecting the inflater each time. But that's just a WAG.

Any thoughts from the crowd? :)
 
First guess would be valve having a slow leak. Some soapy water would show if that is the problem. It can be tightened if that is the case
 
I know I am opening a big can of worms but...My tires and struts hold nitrogen much longer then compressed air.
I also have noticed my wife's and I bike tires stay up longer with nitrogen than with compressed air. I don't think I am imagining it.
Like said soapy water is what to use to check for leaks.
 
Hang 4 said:
First guess would be valve having a slow leak. Some soapy water would show if that is the problem. It can be tightened if that is the case
Click to expand...
Gary Ward said:
I know I am opening a big can of worms but...My tires and struts hold nitrogen much longer then compressed air.
I also have noticed my wife's and I bike tires stay up longer with nitrogen than with compressed air. I don't think I am imagining it.
Like said soapy water is what to use to check for leaks.
Click to expand...
Thanks guys. I'll use soapy water and see if there's anything noticeable.

I'm using compressed air not n2 for the tires.
A few months ago I looked at getting a nitro bottle from airgas so I could use N2 (and so I could add to my struts, when needed). But with the tank cost, the regulator, the adapter to actually fill up the tires... Juice wasn't worth the squeeze on that one. I think it was like $600 for the most basic solution. Compare that to a $50 air compressor :)
 
Lindberg said:
Is the air the same temperature every time you're checking it?
Click to expand...
Yeah, it's in a climate controlled t-hangar. And I only check it when I'm arriving at the hangar and it's been sitting overnight. So I think it's at a near constant temp.
 
Stan’s No Tubes and Orange Seal are in all of my airplane tires and I have both on my shelf in the hangar. Look on-line or at a local bicycle shop. My 35” Bushwheels ($4700 for the pair) had Orange Seal injected before they got valve cores and air.
 
I have an electric unicycle KS14D. I was having a terrible time with it losing pressure and changed the 14 x 2.125 tube twice. I found the new tubes had leaks along the seams of the tube. I used a can of Fix-A-Flat. Problem solved.
 
Bell206 said:
Could be several reasons. But first I'd service the tire to max pressure then mix some Dawn and water and spray the whole tire. If you have wheel fairing installed take it off. For example have seen very slow leaks at the tire awl vents.
Click to expand...
Appreciate it, I'll give that a whirl today
 
Michelin airstop tubes greatly reduce leakage. There are also leakguard tubes which perform better than standard tubes, but the Michelins are the best, IMO.

You may have one type of tube in the mains and a different one in the nosewheel.
 
ArrowFlyer86 said:
Thanks guys. I'll use soapy water and see if there's anything noticeable.

I'm using compressed air not n2 for the tires.
A few months ago I looked at getting a nitro bottle from airgas so I could use N2 (and so I could add to my struts, when needed). But with the tank cost, the regulator, the adapter to actually fill up the tires... Juice wasn't worth the squeeze on that one. I think it was like $600 for the most basic solution. Compare that to a $50 air compressor :)
Click to expand...
Yea I know that stuff is expensive. Over the years I have used nitrous oxide in race cars and CO2 for beer taps.
I have 8 nitrous tanks that got swapped out after every run. I ran 2 of them side by side in the nose of a dragster. Not using nitrous any more so I converted a couple of those tanks to nitrogen by installing a nitrogen valve.
We send tanks out for hydro test since we fill CO2 at work so the tanks are kept in test.
Then we use large nitrogen tanks at our bulk plant for emergency shut offs. I refill my small tanks with a trans fill hose from the large tanks.
Pretty much the same way I refilled my nitrous tanks from the mother tank only it was liquid gas with the mother tank inverted to flow liquid . Nitrogen is a gas, high pressure gas. So I don't have take it somewhere to refill it.
14513c6d-318a-4cf9-85c9-11c795919f1e.jpg



We also used these small CO2 tanks that got switched out every run to shift the transmission. That is a trans fill hose.
595b972c-3c34-4514-af14-7bc4b1292999.jpg

How I shifted the transmission.
9f5a4bef-a41b-45be-ac8e-f0e661b700cd.jpg
 
Last edited:
I keep a nitrogen bottle in the hangar for my shocks. No need to put it in tires. Solve the porosity issue and the pressure won’t bleed out.
 
kyleb said:
Michelin airstop tubes greatly reduce leakage. There are also leakguard tubes which perform better than standard tubes, but the Michelins are the best, IMO.

You may have one type of tube in the mains and a different one in the nosewheel.
Click to expand...
I have LeakGuard on all 3.
The former nose tube (also leakguard), got a pinhole leak and ran flat in september. The FBO only had leakguard tubes as an option if I wanted to get out that day. So that's what I got :)

Gary Ward said:
Yea I know that stuff is expensive. Over the years I have used nitrous oxide in race cars and CO2 for beer taps. I have 8 nitrous tanks that got swapped out after every run. I ran 2 of them side by side in the nose of a dragster. Not using nitrous any more so I converted a couple of those tanks to nitrogen by installing a nitrogen valve. We send tanks out for hydro test since we fill CO2 at work so the tanks are kept in test.
Then we use large nitrogen tanks at our bulk plant for emergency shut offs. I refill my small tanks with a trans fill hose from the large tanks. Pretty much the same way I refilled my nitrous tanks from the mother tank. So I don't have take it somewhere to refill it.
14513c6d-318a-4cf9-85c9-11c795919f1e.jpg



We also used these small CO2 tanks that got switched out every run to shift the transmission. That is a trans fill hose.
595b972c-3c34-4514-af14-7bc4b1292999.jpg

How I shifted the transmission.
9f5a4bef-a41b-45be-ac8e-f0e661b700cd.jpg
Click to expand...
Given the other photos you've posted of your hangar and tools, this surprises me very little :)
You've got a much, much more advanced workshop and tooling setup than me with my 1-2 small tool boxes with wrenches and screwdrivers. I think my most "advanced" tool is a torque wrench :p
 
ArrowFlyer86 said:
I've been diligent about checking tire pressure ever since a nose-wheel tube went flat in September and stranded me overnight off home base.

In doing this I've noticed my brand new nose tire loses pressure faster than my mains.

While I might only lose 2psi in my mains between checks (LH/RH seem to always match), it's common I'll lose 8psi in my nose gear over the same time. The nose has a brand new tube installed in September, mains are same make but 1 year old.
Only idea was wondering if it was measurement error on my behalf... The smaller volume of the nose tire being more impacted by that couple seconds of HISSSSSS where it bleeds air out while I'm connecting/disconnecting the inflater each time. But that's just a WAG.

Any thoughts from the crowd? :)
Click to expand...
You should consider temperature changes.
Also if you do the soap check make sure to check the valve stem.
 
ArrowFlyer86 said:
While I might only lose 2psi in my mains between checks (LH/RH seem to always match), it's common I'll lose 8psi in my nose gear over the same time.
Click to expand...
First off, how often do you check?
 
Stewartb said:
Stan’s No Tubes and Orange Seal are in all of my airplane tires and I have both on my shelf in the hangar. Look on-line or at a local bicycle shop. My 35” Bushwheels ($4700 for the pair) had Orange Seal injected before they got valve cores and air.
Click to expand...
Which version do you use, Regular or Endurance, and how much? Am I correct to assume the following process? The valve core is removed, the goop squirted in, valve core replaced, tire inflated, and go taxi fast.
 
First thing is to stop using an inflator kit to check pressure. Use a stab only type gauge. The only time we hook an inflator up to a tire is to actually inflate it. All daily tire checks are done with a stab gauge. I can stab a nose tire for about 10 days of checks before I need to bring the pressure up on it. Our nose tires run 270 or 300 psig nominal, depending on A/C model.
 
Craig said:
First thing is to stop using an inflator kit to check pressure. Use a stab only type gauge. The only time we hook an inflator up to a tire is to actually inflate it. All daily tire checks are done with a stab gauge. I can stab a nose tire for about 10 days of checks before I need to bring the pressure up on it. Our nose tires run 270 or 300 psig nominal, depending on A/C model.
Click to expand...
Sounds like an easy first step to take, thanks! Any specific ones you'd recommend or are they all pretty much the same accuracy?
 
ArrowFlyer86 said:
Sounds like an easy first step to take, thanks! Any specific ones you'd recommend or are they all pretty much the same accuracy?
Click to expand...
Ours are Mil-Spec Miltons, but they go to 750 psig. Milton, Longacre or Intercomp are all high quality. We've gone to all digital at work and are phasing out the analog and stem type gauges. I wouldn't drop the coin on any of them being above around 50-75$, as you don't need that kind of accuracy and repeatability. If you like analog dial only, there are a number of them that are not at that price level. Just remember, dropping an analog dial gauge, even a foot to a hard surface can knock it out of calibration.
 
Domenick said:
Which version do you use, Regular or Endurance, and how much? Am I correct to assume the following process? The valve core is removed, the goop squirted in, valve core replaced, tire inflated, and go taxi fast.
Click to expand...
That’s the procedure. Stan’s uses a syringe to inject, Orange Seal has an injector tip on the bottle. I’ve ised both. The Orange Seal I have is the non-freezing type but I don’t think it matters if you inject it in warm temps. I did mine in the hangar and spun the tires for a couple of minutes. No air adjustments needed since, and that was 6 years ago. Longer on the Cessna with Stan’s.
 
ArrowFlyer86 said:
Only idea was wondering if it was measurement error on my behalf... The smaller volume of the nose tire being more impacted by that couple seconds of HISSSSSS where it bleeds air out while I'm connecting/disconnecting the inflater each time. But that's just a WAG.
Click to expand...

So then double thd pressure check period and see if the pressure loss is halved :D
 
455 Bravo Uniform said:
So then double thd pressure check period and see if the pressure loss is halved :D
Click to expand...

But would it be halved? :oops:
Or I could...
1) Inflate tires to appropriate pressure, then disconnect.
2) Immediately reconnect inflater and check the pressure
3) Any difference btw inflation pressure and the new pressure could be chocked up to the loss from unplugging/plugging it back onto the tire valve.

*chin scratch...

Craig said:
Ours are Mil-Spec Miltons, but they go to 750 psig. Milton, Longacre or Intercomp are all high quality. We've gone to all digital at work and are phasing out the analog and stem type gauges. I wouldn't drop the coin on any of them being above around 50-75$, as you don't need that kind of accuracy and repeatability. If you like analog dial only, there are a number of them that are not at that price level. Just remember, dropping an analog dial gauge, even a foot to a hard surface can knock it out of calibration.
Click to expand...
Thanks for the rec. I'll get a reasonable quality one and stop using the inflater gauge as my only means of checking pressure.

Still going to do the soapy water test today and see what that looks like. Will report back.
 
I’ve had bad luck with tires, now my rule is don’t touch it, and once you got a decent tube in, seems to last much longer. Those valve stems are sensitive, better to not touch it, especially when not at your home airport, and carry spares in the baggage compartment.
 
mandm said:
I’ve had bad luck with tires, now my rule is don’t touch it, and once you got a decent tube in, seems to last much longer. Those valve stems are sensitive, better to not touch it, especially when not at your home airport, and carry spares in the baggage compartment.
Click to expand...
There might be some wisdom to that approach. I never used to touch my old tubes/tires and they lasted >3.5y (~550h+), and I inflated them maybe 1x in-between annuals?
But after my newer tires were installed and the nose tube ran flat last fall (after <1yr in service), the A&P consensus seemed to be that people not paying attention to tire inflation is a problem. So I started paying attn to it. And that's when I've noticed that the nose loses pressure quicker.

Anywho! Taking plane over to A&P in an hour to get N2 for the struts, will do the soapy water test in the hangar before hand and also get A&P opinion on the inflation issue. Will report back after.
 
Last new tube I had doing this was corrected by tightening the schrader valve. A SLOW two week leak.
 
Don’t think mine would have showed either, and it didn’t feel like it tightened, but the slow leak stopped.
 
Arrow: For an information data point on servicing tires...We typically over inflate by 5-20 psig, then remove the inflator rig. We then give it up to 10 minutes before going back and checking with our digital gauges. By that time, the pressures have generally settled down and if they are above the limit, we bleed them down to with spec. Consider though, we operate with tire pressures between 210 psig and 310 psig, depending on tire and aircraft model and service.
 
Gary Ward said:
I know I am opening a big can of worms but...My tires and struts hold nitrogen much longer then compressed air.
I also have noticed my wife's and I bike tires stay up longer with nitrogen than with compressed air. I don't think I am imagining it.
Like said soapy water is what to use to check for leaks.
Click to expand...
nitrogen molecules are larger than 'air' so if you use 100% nitrogen there is no oxygen to seep out of the rubber tire and lose psi. some N2 will still seep out but at a much reduced rate
 
According to WebElements, O2 (double bonded) is slightly bigger than N2 (triple bonded).
There are multiple ways to determine molecular size. Remember, these are oblong so they have two axes. The numbers below are the long axis, and I believe pm is pico-meters.
N2 109.76 pm
O2 120.74 pm

There are other ways to measure molecular size. All seem to show O2 slightly larger than N2.

HOWEVER, at these scales molecular size is irrelevant. Size is not the only determinant of permeability. Reactivity is a bigger factor. The operative characteristic of whether N2 or air leaks faster through the tire material is specific permeability of the gas through the material.

WebElements Periodic Table » Oxygen » radii of atoms and ions

www.webelements.com www.webelements.com

WebElements Periodic Table » Nitrogen » radii of atoms and ions

www.webelements.com www.webelements.com

I leave permeability as a search exercise for others.
 
Craig said:
Arrow: For an information data point on servicing tires...We typically over inflate by 5-20 psig, then remove the inflator rig. We then give it up to 10 minutes before going back and checking with our digital gauges. By that time, the pressures have generally settled down and if they are above the limit, we bleed them down to with spec. Consider though, we operate with tire pressures between 210 psig and 310 psig, depending on tire and aircraft model and service.
Click to expand...
Bought a digital air pressure gauge that I don't have to screw on (I believe that's what you meant by "stab" gauge?). I just press it against the valve and it takes a near-instant reading with minimal air loss.
Yesterday before my flight I overinflated the tires by 2 PSI. Then used my new digital gauge and bled off a little air until they were right at the correct PSI.

I'll check again in a week and see where they're at.
 
Arrow: Yep, a stab gauge is one you simply push on to make a measurement, rather than screw on.
 
Anyone want to split a four pack of these (valve cap with colored pressure indications):
32-35 psi Green
27-31 psi Yellow
Below 27 psi Red

That would take care of my mains.
I need one that covers 45 psi for my nose wheel.

Oh, wait. My valve caps are covered by my Hubba Hubba caps. Darn.

 
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