Posted On: Wednesday - August 28th 2024 10:21AM MST
In Topics: General Stupidity Media Stupidity Science
There's a tragic story from yesterday about 2 Delta mechanics who got killed (and another seriously injured) when a 737 tire exploded at one of their big facilities at the Atlanta Hartsfield Airport. That headline above pissed me off. It's just the site of the Fredericksburg Free Lance Star*, filled with people who don't know squat about squat. Other headlines that came up don't mention Boeing other than that the airplane these tires go on was a B-737.
However, this has been a mindless narrative thing. I do realize Boeing's non-engineering-based culture of the last few decades, along with the D.I.E. programs, have brought their quality down. They don't freaking make tires though, and these tires weren't even on an airplane!
The tires are made by Michelin or Dunlop, or Bridgestone, etc., some of which may come from China, along with Quintao made brand Sentury.
The guys were doing some work on wheels (probably a specialty, as there are a LOT of them there), maybe replacing brake rotors, etc. Those tires are pressurized to around 200 psi. Weirdly, I was walking around an airplane a couple of days ago and thought of how much energy is contained in those things.
Anyway, hopefully some sharp engineers from the tire manufacturer - NOT BOEING - and from the shop will figure out how this happened. It was tragic, but one doesn't have to make the story into something it's not, another Boeing quality issue.
PS: Then some other article mentioned the pressurized tires as "1 million pound-feet of force". Freaking idiots. Let me do the math for fun then. Filled up, they are at 185 psi gage pressure (above atm), and the Nitrogen can be considered an ideal gas. The 737 main gear tires are 27 x 7.5R x 15. That's 27" O.D., 7.5" wide and with a 15" rim diameter.** Let me approximate this torus shape as having a volume of ~ 3,500 in3. I get only ~ 625,000 ft-lb in PV work to fill the thing up. (There's some expansion that may bring the volume up more.) The problem I have with the article is not the value, and it's not the units this time, but with their getting the term wrong. It's not a force. That doesn't make sense That's the potential energy of the nitrogen from compression. If it's hot, there's a bit more...
* The local newspaper websites are really bad about not saying where in the hell they are in the country. It could have been another Fredericksburg, so I had to go to the "Contact" page to find out this is the Virginia Fredericksburg.
** At least they're not weirdly mixed units as with car tires. They use inches for the I.D., mm for the width, and then % for the sidewall height (% of width, that is).
Comments:
SafeNow
Wednesday - August 28th 2024 6:19PM MST
PS
Being true to my handle, I was curious to read a little about tire inflation procedures, and I found a short video of a tire exploding in its cage. OMG.
https://www.youtube.com/watch?v=HANwJp8Z5mc
Being true to my handle, I was curious to read a little about tire inflation procedures, and I found a short video of a tire exploding in its cage. OMG.
https://www.youtube.com/watch?v=HANwJp8Z5mc
Moderator
Wednesday - August 28th 2024 4:06PM MST
PS: Oh, yeah "Sentury", not "Sentinel" - I'll fix that in a minute. Thanks, Alarmist.
Moderator
Wednesday - August 28th 2024 4:04PM MST
PS: Retreads are bad enough on cars, Alarmist, but I sure wouldn't want to see them on airplanes! Do they even have car retreads anymore? I got a couple of used tires only once - they were for a car that cost only $1,300 and the thing spit out oil smoke from the time I got it from the guy (who would answer no more phone calls.)
I don't know all those details, either, Possumman. One article read as if the wheel, not specifically the tire, was being worked on. I guess the tire stays inflated. After all, they sit on airplanes all day, with that occasional hard wear and tear. I thought I remember that the 747 tires were good for only 20 cycles or something. It being an 18-wheeler of the airways, that means nearly one new tire needed per flight, on average. OTOH, a flight would be 8 to 14 hours on those planes, if they were used right.
I don't know all those details, either, Possumman. One article read as if the wheel, not specifically the tire, was being worked on. I guess the tire stays inflated. After all, they sit on airplanes all day, with that occasional hard wear and tear. I thought I remember that the 747 tires were good for only 20 cycles or something. It being an 18-wheeler of the airways, that means nearly one new tire needed per flight, on average. OTOH, a flight would be 8 to 14 hours on those planes, if they were used right.
Possumman
Wednesday - August 28th 2024 2:55PM MST
PS Really not enough info in the article --maybe it was being refilled and not in the cage (to save five minutes) and exploded or split rim came apart--I know nothing about airplane wheels but 200 psi is a lot of PSIs and is nothing to fool around with---people are killed or maimed by truck tires every year
The Alarmist
Wednesday - August 28th 2024 2:14PM MST
PS
Qingdao Sentury Tires or a Dunlop retread from China.
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Qingdao Sentury Tires or a Dunlop retread from China.
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I'm guessing the tire that exploded has some defect introduced through use or a foreign object deeply embedded somewhere.