Hey guys,

Got a interesting one for ya,

A couple days ago I was going to fly over to VT for a overnight, I preflight the plane, go get some fuel, go to the main terminal to use the head, alls good.

On taxi back to the runway and just before the hold short lines I feel a little dragging on my right float (Edo 2790s), taxi off the active and hop out to see my right nose wheel tire is FLAT, it's a new tire and tube with <20hrs, no visible puncture, nice taxi ways, I'm super gentle on the plane, any ideas on the cause?

NineThreeKilo wrote:Hey guys,

Got a interesting one for ya,

A couple days ago I was going to fly over to VT for a overnight, I preflight the plane, go get some fuel, go to the main terminal to use the head, alls good.

On taxi back to the runway and just before the hold short lines I feel a little dragging on my right float (Edo 2790s), taxi off the active and hop out to see my right nose wheel tire is FLAT, it's a new tire and tube with <20hrs, no visible puncture, nice taxi ways, I'm super gentle on the plane, any ideas on the cause?

Well, that's easy: All the air escaped.

I'd bet you got a bad tube, or a bad valve. Did you check tire pressure prior to start? It was probably already flat, or close and taxiing just finished the job.

I'd change the valve insert first, pump it up and leave it overnight to see if it holds. Check pressure frequently till you're convinced it's fixed. If that doesn't fix it, pull the tube, pump it up a bit, and shove it underwater to see where the bubbles come from. It may be fixable, but if a brand new tube is bad and it's not just the valve, I'd call whoever I got it from and buy a new tube. They should replace at no charge. Leaky tubes aren't common, but it happens.

And, be glad it wasn't a main. Been there, done that, and you're done moving without a lot of assistance.

MTV

I don't know how stiff the sidewall is, but the look and feel of the tire might have been right with the psi actually a little low, and you sheared a valve stem from the tire rotating on the wheel. I did that one time on my Cub, 8.50 Goodyears have a stiff sidewall and looked and felt right, but the psi was too low (8 psi on the main that held) and I sheared a valve stem, luckily while it was parked after landing.

CenterHillAg wrote:I don't know how stiff the sidewall is, but the look and feel of the tire might have been right with the psi actually a little low, and you sheared a valve stem from the tire rotating on the wheel. I did that one time on my Cub, 8.50 Goodyears have a stiff sidewall and looked and felt right, but the psi was too low (8 psi on the main that held) and I sheared a valve stem, luckily while it was parked after landing.

Maybe, just with a new tire and tube, hardly any time on it, I wouldn't think it would bleed down like that, and it was put up to 41psi per the POH supplement.




I was able to get some of the line guys at the airport to toss some air into it and it held it for a couple minutes, then I had to pull the nose wheel up by hanging from the stinger, while one of the guys put a tire dolly under the nose wheel allowing me to limp the plane back over to my hangar

NineThreeKilo wrote:

CenterHillAg wrote:I don't know how stiff the sidewall is, but the look and feel of the tire might have been right with the psi actually a little low, and you sheared a valve stem from the tire rotating on the wheel. I did that one time on my Cub, 8.50 Goodyears have a stiff sidewall and looked and felt right, but the psi was too low (8 psi on the main that held) and I sheared a valve stem, luckily while it was parked after landing.

Maybe, just with a new tire and tube, hardly any time on it, I wouldn't think it would bleed down like that, and it was put up to 41psi per the POH supplement.




I was able to get some of the line guys at the airport to toss some air into it and it held it for a couple minutes, then I had to pull the nose wheel up by hanging from the stinger, while one of the guys put a tire dolly under the nose wheel allowing me to limp the plane back over to my hangar

Get a new tube. Life's too short to screw with stuff like that. As I said, try a new valve core first if you want.....that's the most likely culprit. But, I've had bad tubes brand new.

And, yes amphibs are a PITA to move when ANY tire goes flat.

MTV

I haven't yet had a flat tire on an airplane (knock on wood) in the 43+ years I've been flying, but I've had beau coup flats on cars, trucks, and bicycles. The usual cause is FOD, typically a small nail.

But the most common second cause, especially if it happens rather suddenly, is a leaky valve stem, almost always caused by a bad or loose valve core. First check to see if it's tight--surprising how many new valve stems and tubes have loose cores--and if that doesn't take care of it, as a temporary fix, it can be pulled, cleaned with just saliva and fingers, and replaced, and then pump up the tire again. Then replace the core as soon as possible--$2 for peace of mind. That's why I always make a point on every vehicle of having at least one valve cap that is a core wrench. It's also a good idea to replace any valve caps which are missing, because it doesn't take much dirt in there to open the core and start it leaking.

Cary

I'll try the core and go from there, thanks for the info guys, I would have defaulted to just replacing the tube otherwise

Possibly a pinched tube?

New day-New lesson:
Almost, but not quite, ashamed to say that in sixty + yrs around airplanes I had never heard anyone speak of MAINS on an amph. Not even after having to hang around Lake Hood for most of a week. Not even watching them land on pavement. Made obvious sense after I stopped reading at the word "mains" for a second.

Chris C

Fill the removed tube and dunk it in water, look for the bubbles.
If likely, then check the inside of the tire casing for burrs or a sharpy.
I had a t/w tire that had a burred spot inside of it, manufacturing defect apparently, that punctured two different tubes. Good idea to save your old t/w (in your case, nosewheel) tires and tubes as spares.
I carry one tire/tube set in the airplane, and have two other sets in the hangar.
Just recently had occasion to offer one to Flyhound when his Maule came up with a flat.

Here is an interesting little gadget for small aircraft. I just put 4 new tires with new remote pressure sensors on my Jeep. Ouch. Anyway, I was curious what the deal might be for small aircraft, and again, Google is my friend. At Aircaft Spruce.

http://www.amazon.com/Accutire-MS-4378G ... B002PMM9N2

$82 on Amazon. And has a spare pressure monitor in case one of the other three goes bad

Sent from my LG-D850 using Tapatalk

Got a lot of bad reviews and I would be concerned that it would upset the balance of the tires. I just hape driving a vehicle with unbalanced tires.

Geez, guys.....just buy a good digital tire gauge and check pressures once in a while. Cheap and easy. Doesn't have to be every flight, maybe once a month, unless you're running REALLY low pressures. No need for a bunch of gadgets, and more crap in the cockpit. Tires don't fail that often.

MTV

Ditto on the tire gauge, unless you just have too much money and have run out of other cool shit to buy.
I recently bought my first tire digital gauge when I realized that the three cheapie stem-type tire gauges I had all gave (sometime wildly) different readings. Seems accurate, I really like it. About $10 at NAPA.

Well it turned out to be a tube tear right by the base of the valve stem.

Denali wrote:Here is an interesting little gadget for small aircraft. I just put 4 new tires with new remote pressure sensors on my Jeep. Ouch. Anyway, I was curious what the deal might be for small aircraft, and again, Google is my friend. At Aircaft Spruce.

That little device might not be as ridiculous as some think. Picking up a nail on your take-off roll and not realizing you have a flat tire when you land is a guaranteed way to scuttle your airplane. You might bend her regardless, but if you know your tire is flat at least you've got a shot at keeping it under control, and you can burn off excess fuel and choose your landing site with a potentially bent airplane in mind.

I run Norton no-tubes sealant in my tires, but I can attest from using it in bicycle and motorcycle tires that while it helps, it's far from a sure thing.

Here's a picture of the nails I collected at one end of a popular Idaho airstrip.