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Old 02-07-2019, 06:57 PM
SHARKBITEATTACK SHARKBITEATTACK is offline
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What would cause an airplane to lose a tire like this after landing?

https://www.youtube.com/watch?v=FzKyvv9c-K0
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Old 02-07-2019, 06:59 PM
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silenus silenus is online now
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You mind telling us where in the video the blowout is? I'm not watching all that just to find the spot.
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Old 02-07-2019, 07:23 PM
Gorsnak Gorsnak is offline
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13:50
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Old 02-07-2019, 07:58 PM
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Brake locked due to some malfunction and the tire spun on the wheel assembly and run itself off. You can see that the wheel did not rotate after the tire was gone and started to grind off immediately causing the fire.

YEMV
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Old 02-09-2019, 07:02 PM
Magiver Magiver is offline
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Originally Posted by GusNSpot View Post
Brake locked due to some malfunction and the tire spun on the wheel assembly and run itself off. You can see that the wheel did not rotate after the tire was gone and started to grind off immediately causing the fire.

YEMV
If the brake locked up I would expect it to yank the plane hard to port. I've had a tire give out on takeoff rollout and it dragged the plane off the runway (no differential braking involved). it was just the drag of the flat tire.

If that was a magnesium rim then that would explain the fire.
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Old 02-11-2019, 10:30 AM
md2000 md2000 is offline
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I don't recall the exact incident but many years ago in Canada there was a tire failure - I think it caused an engine failure when the engine ingested rubber, back when engines beside the tail was a common configuration. During the inquiry it was discussed about airline tires that they burned off tread very quickly (the puff of smoke on initial touchdown) and so were retreaded, often over and over. The involved tire had been retreaded, a new layer of rubber added, 6 times before this failure.

Not sure if this is still common practice for airlines.

I did hear about a local incident once where a small plane was flying in extreme cold - the brakes had frozen on one side, so when the plane touched down, the tire spun on the rim - also shearing off the tube filler valve so the tire went flat, and the total result was it veered off the runway...

My first BMW in 2000 would get flat tires in extreme cold, and the local tire shop attributed it to the rim shrinking in the cold and that the Germans had not applied a special goop to make the (tubeless) tires stick to the rims. Once he applied that, no more flats.

Last edited by md2000; 02-11-2019 at 10:32 AM.
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Old 02-11-2019, 11:01 AM
Machine Elf Machine Elf is online now
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Originally Posted by md2000 View Post
I did hear about a local incident once where a small plane was flying in extreme cold - the brakes had frozen on one side, so when the plane touched down, the tire spun on the rim - also shearing off the tube filler valve so the tire went flat, and the total result was it veered off the runway...


This implies that the plane's tire has such amazing grip on the pavement that it would be possible under normal everyday circumstances for a pilot to stomp on the brakes hard enough to cause a tire to spin on its rim. Unless a pilot chimes in here to confirm that this is something that small-plane operator manuals warn about, I'm going to say it's not possible. Even the most powerful street-legal cars don't have problems with tires spinning on the rims; you have to get to high-performance drag racing tires that operate with extreme grip, very low pressure, and ridiculous traction forces before you worry about the tires slipping on the rims.

If the tire on that plane really did spin on the rim, then the tire pressure must have been extremely low. Like almost-flat.
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Old 02-11-2019, 11:42 AM
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Some physical forces are awesome.
1964, Near Ft. Bragg. Dirt runway, A-1E Skyraider, landed with the left wheel GONE! Strut & axle left. Dug a furrow down the runway. Barely made the AC go to the left with the pilot holding right rudder and judicious power adjustment.

The video is showing a WW2 heavy aircraft just after almost full weight on a good hard surface and with an instant lockup on 1940's tech wheels and unknown wheel to tire grip, actual rotation speed due to unknown A/C speed and this accident is is not understood?

My Dad, a pilot from 1937 to 1980, was an acceptance pilot for A/C right out of the Tulsa Douglas Plant and/or modification center in WW2. The hundreds of things going wrong on a daily basis would make today's pilots hair curl. A-20, B-24, B-17 in the modification hangers, A-26, B-25 in for modifications and more. You all have no idea

I have over 10,000 hours, 1965 to 1998, with about half of that in really bad aircraft. "Oh, that could not happen." says today pilot. Bawahahahaha Had the almost identical thing happen in Lafayette LA in an old 1956 C-180 with Bendix brakes. Yes, even with a small plane & 1956 tech, amazing "OOP'S" can & do happen. It turned the most perfect landing I had ever made to that point, about 2000 hrs., into a keystone Cops Comedy routine. ::: sigh ::::

I would rather be flying but too old and unhealthy. Golden years my backside..................
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Last edited by GusNSpot; 02-11-2019 at 11:44 AM.
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Old 02-11-2019, 02:01 PM
md2000 md2000 is offline
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I think the rims were aluminum which contracts more than steel? (anyone know off hand what old Cessna wheels would be made of?) -20F, Lock brake, shrink rim, reduce air pressure due to cold... All could contribute to making the tire spin.

Landing while standing on the brakes is not a recommended procedure. I heard the apocryphal story of one fellow who tried something like that and ended up nose into the ground.

Last edited by md2000; 02-11-2019 at 02:01 PM.
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Old 02-11-2019, 04:39 PM
Machine Elf Machine Elf is online now
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Quote:
Originally Posted by md2000 View Post
I think the rims were aluminum which contracts more than steel? (anyone know off hand what old Cessna wheels would be made of?) -20F, Lock brake, shrink rim, reduce air pressure due to cold... All could contribute to making the tire spin.
Aluminum does contract more than steel; its coefficient of thermal expansion is about 12E-6 per degree F (and magnesium is only about 14E-6). But the amount involved doesn't matter unless you're going for a precision fit between two metal parts. Fitting a tire on a rim? Thermal contraction of the rim is negligible: supposing an aluminum rim diameter of 6 inches at 70F, the rim diameter at -20F would be 5.994 inches. The tire bead size spec probably has a far larger tolerance than that.

Moreover, the vast majority of the tire's grip on the rim is due to lateral force on the rim lip caused by tire pressure against the tire's sidewalls. Even if we suppose the tire was inflated to 40 psi at 70F before takeoff, and then he landed at -20F, the tire would still have 30 psi in it. That should be plenty to maintain rotational grip on the rim.

Ultimately, even if the rim did shrink appreciably in the radial direction, and even allowing for bizarrely large temperature differences between takeoff and landing, there shouldn't be a problem with the tire gripping the rim unless the tire was grossly underinflated in the first place.

If you go back to the OP's video and pause it at just the right moment around 13:57, you'll see parts flying through the air. One part in particular looks like about 3/4 of a circle. My guess is that that's the lip of a failed rim. The tire itself in that freeze-frame and after (see e.g. at/after 14:03) looks remarkably intact. If the tire bead had failed during this incident, ISTM we should also see the sidewall torn up pretty good. Also, the inboard bead would have likely remained intact, keeping the whole tire carcass safely on the rim. The fact that the tire evacuated to the right is a pretty good indication that that right rim lip is gone.

Also also, notice that the rim doesn't start sparking on the tarmac until several seconds after the tire departs. If there were any braking at all going on when the tire failed, the rim would have stopped instantly and begun sparking severely as soon as it touched the pavement.

Another video of the same incident, see at 0:02. There is a brief spark when the rim touches the ground, but I don't believe this is due to braking forces. That bit of sparking stops almost as soon as it starts, and the rim is on the ground a fraction of a second after the failure; if the pilot was braking, there's no way he could have reacted (and released the brake pedals) that quickly. More likely this is due to the rim not spinning at the same surface speed as the pavement is going by: it's much smaller in diameter than the tire, so it has to rotate faster to keep up with the pavement going by, and it takes a moment to pick up that speed, just like the tire does at initial touchdown.

If you freeze that video at the right moment, there seems to be "smoke" coming from the entire circumference of the bead simultaneously at the moment of failure. This doesn't seem to be the tire bead failing at a single point - it's more consistent with a fatigue crack around circumference of the rim lip, such that the whole thing was almost ready to fail, and when it finally did crack enough at one spot, the whole rim lip "unzipped" in a microsecond.

I put "smoke" in quotes in the previous paragraph because I don't believe it's smoke. If you study how the cloud dissipates in the moments after the failure, it looks much more like condensation. This has two possible explanations:

#1: the tire was filled with moist air. AIUI, this is a no-no on most aircraft, as the high pressures and high temperatures can cause fire inside the tire, with subsequent overpressure and failure.

#2: the violent eruption of pressurized air generated a shock wave, followed by a low-pressure rarefaction wave. Under humid conditions, that rarefaction wave can lower the local temperature below the dew point, causing condensation (look at aerial footage of bomb blasts during the Vietnam war, and you see the same thing happening).

Of the two possibilities, I think #1 is more likely because the condensation is apparent in the actual gas emitted from the rim. If the tire gas were dry nitrogen, you wouldn't see "smoke" coming from the tire, you'd see nothing...until the rarefaction wave propagated farther out beyond the released dry nitrogen and into the surrounding humid air.

Bottom line, I don't think the OP's video shows a tire failure - I think it shows a rim failure. The use of wet air on a long-term basis to inflate the tire might have aided corrosion that weakened the rim lip and precipitated the failure.
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Old 02-11-2019, 06:10 PM
EdelweissPirate EdelweissPirate is offline
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MD2000 has posted about his BMW’s cold-weather flats before, I’m pretty sure. I fully agree with your assessment, Machine Elf: cold weather doesn’t cause tires to spin on wheels in general, and it’s exceedingly unlikely that the tire was spinning on the rim in this case.

That said, bead locks are a thing for some tubed motorcycle wheels. These provide a mechanical, non-pneumatic clamping force at a few points around the rim. In motorcycle mythology, bead locks keep the tire from migrating around the rim under acceleration and braking. This matters for tubed tires because the tire could take the tube with it as it migrates, causing the valve stem to rip away from the tube, which would obviously cause a flat.

Under very low inflation pressures, bead locks may serve a purpose, but for modern wheels/tires (tubeless and radial) tires rotating around rims isn’t really a thing. I mean, there are always exceptions, but the forces retaining a modern tire on a modern rim are nontrivial.

MD2000, I don’t doubt that your tire shop told you in good faith that your flats were due to wheel shrinkage, but they’re almost certainly mistaken. The coefficients of thermal expansion for common aluminum alloys and for butyl and similar rubbers are of the same order of magnitude. Inflation pressure holds the tire tightly to the rim. The sealant you mention solved your problem, but not for the reasons your tire shop believes.

Machine Elf, I think you’re on the right track regarding that condensation, but you’ve kind of set up a false dichotomy. The tire in the video could be filled with perfectly dry air (or just nitrogen) but you’d still get condensation after a blowout. You don’t need a strong negative pressure wave to get condensation—sudden decompression of any gas from ~80 PSIG to ambient will easily cool the gas (and some part of the surrounding air) below the dew point on a warm summer day in Wisconsin. The dew point that day hovered around 60 degrees F, and an exploding tire would easily cool the surrounding air below that point, creating the condensation you likely saw.

I agree that the video likely shows a rim failure. I suppose it’s possible that someone put a radial tire on that rim when it was meant for bias-ply tires (which constrict on the rim as they’re inflated, unlike radial tires). A loose radial on a barely-in-spec wheel designed around bias-ply tires still wouldn’t be loose enough to spin on the rim, IMHO.
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Old 02-11-2019, 06:26 PM
EdelweissPirate EdelweissPirate is offline
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I forgot to mention that if the F7F Tigercat had magnesium wheels—and it may well have—then we should remember that magnesium is prone to corrosion. Corrosion could easily cause the kind of failure that Machine Elf describes.

Magnesium wheels were common on WWII fighters like the Tigercat, but if those are magnesium wheels, I’m not sure it’s the wheel itself that catches fire in the video. If it had, it wouldn’t just go out like that. If magnesium was burning, it probably wasn’t the wheel itself but rather magnesium powder that had been ground away from the wheel as it sheared against the runway.

Also, burning magnesium is so bright that it looks like an electrical welding arc—it’s painful to look at. The flames in the video don’t look bright enough and they look too yellow to my eye to be magnesium, but it’s really hard to judge absolute brightness and color in digital video without a good reference.
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Old 02-12-2019, 10:48 AM
DesertDog DesertDog is offline
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Quote:
Originally Posted by silenus
You mind telling us where in the video the blowout is? I'm not watching all that just to find the spot.
For future reference, if you right-click in the video frame while YouTube is running a menu pops up, and one of the choices is Copy URL at current time. It will append the URL with t=nnn and you can paste that into the post. I always preview because my reflexes aren't all that good and I have to zero in on the spot I want. The video will play to the end, but at least you can start it at the good part.
Quote:
Originally Posted by md2000 View Post
My first BMW in 2000 would get flat tires in extreme cold, and the local tire shop attributed it to the rim shrinking in the cold and that the Germans had not applied a special goop to make the (tubeless) tires stick to the rims. Once he applied that, no more flats.
A friend of mine was a victim of a rear-end collision while waiting at a light. It wasn't a bad smash, just a big bump since she was like like the third car struck in the line. I cautioned her to check her tires' pressures and the next day she said, "You were right; they were all down at least eight pounds."

When asked how I knew and how it happened, I just said I read a lot and dunno. Perhaps the sudden push makes the tire slip on the rim or momentarily get unseated.
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