Tire cookoff

gprellwitz said:
And I want to start singing "Stairway to Heaven". At what point do they say "it's too much of a hazard and we're evacuating via emergency means" rather that waiting for the stairs?
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That is what I was wondering. It seemed like everything was well scripted and planned for EXCEPT getting the stairs to the aircraft to get the crew out in the event of fire. Oops
 
Somewhere in YouTube-ville is a 777 test (I think it was a 777). Similar test, similar results.
 
everything was well scripted and planned for EXCEPT getting the stairs to the aircraft
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I didn't think firefighters wandering around near exploding tires was too cool.
 
Let'sgoflying! said:
I didn't think firefighters wandering around near exploding tires was too cool.
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That AND I'd have expected that once they started applying water, they'd have used a widened spray pattern to knock down the heat, instead of a direct stream. The quantitiy of water available seemed pretty minimal too, given that a fire was a real probability in this test...

Of course, it's always easy to second guess.
 
kyleb said:
That AND I'd have expected that once they started applying water, they'd have used a widened spray pattern to knock down the heat, instead of a direct stream. The quantitiy of water available seemed pretty minimal too, given that a fire was a real probability in this test...

Of course, it's always easy to second guess.
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The firefighters seemed pretty unhappy with the quantity of water also!!
 
Let'sgoflying! said:
I didn't think firefighters wandering around near exploding tires was too cool.
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I am pretty sure they did not "explode". Those tires have thermal fuse plugs that melt when the wheels get hot to let the pressure out. They are designed to specifically keep the tires from exploding. I can with almost certainty say that it was the thermal plugs letting go.
 
Greg Bockelman said:
I am pretty sure they did not "explode".
...
I can with almost certainty say that it was the thermal plugs letting go.
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No, they did explode, or at least disintegrate. This was a video of a failed RTO test. Part of the failure was the fire crew needing to intervene before the 5 minutes were up, part was the size of the fire, and part was the disintegration of wheel assemblies. Like you said, fuse plugs are supposed to go and deflate the tires before they burst.

A different angle:

http://www.talkairline.com/aviation-videos-pictures/play.php?vid=328

You can see pieces of the rims and rubber flying around.

--Carlos V.
 
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Matthew said:
Somewhere in YouTube-ville is a 777 test (I think it was a 777). Similar test, similar results.
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Greg Bockelman said:
I am pretty sure they did not "explode". Those tires have thermal fuse plugs that melt when the wheels get hot to let the pressure out. They are designed to specifically keep the tires from exploding. I can with almost certainty say that it was the thermal plugs letting go.
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Same test, very different results. Notice how on the 777 the tires deflated as the fuse plugs melted. They had a successful test.

The wheels and tires on the 340 EXPLODED, the fuse plugs did not release before the wheels and tires. You are correct Greg, they SHOULD have gently released pressure from the fuse plugs, they did not though, that's why the test was a failure and modifications had to be made. Only one of the wheels deflated as it was supposed to, the rest failed catastrophically.
 
I am pretty sure they did not "explode".
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I'm pretty sure this was an example of "failed" fusible plugs, Greg.
I am reading the melting temp of the plugs was set too high and that's why they did not perform properly on this test.

What we are seeing is the wheel halves and/or the tires failing catastrophically with debris being flung a distance away. The narrator even called it an explosion.
With a plug melt, is it not simply noisy ie pop and loud hissing, instead of one loud bang and debris flying? around?
 
Let'sgoflying! said:
I'm pretty sure this was an example of "failed" fusible plugs,
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I'm still amazed at the poor fire fighting effort. Heaven help them if they'd had a real fire like a crash with a few thousand gallons of fuel burning, passengers on board, etc. That looked like a Gilligan's Island effort at fire fighting.
 
I'm still amazed at the poor fire fighting effort. Heaven help them if they'd had a real fire like a crash with a few thousand gallons of fuel burning, passengers on board, etc. That looked like a Gilligan's Island effort at fire fighting.
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I was wondering if the guy in charge of the valve was holding off, on instructions from the test boss.
(It could be that if they used water too soon then they fail the test and have to start all over.)
If not, then the flow appeared meager. Pity the pax in a crash with fire should that be all the water that is available.
 
kyleb said:
I'm still amazed at the poor fire fighting effort. Heaven help them if they'd had a real fire like a crash with a few thousand gallons of fuel burning, passengers on board, etc. That looked like a Gilligan's Island effort at fire fighting.
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Let'sgoflying! said:
I was wondering if the guy in charge of the valve was holding off, on instructions from the test boss.
(It could be that if they used water too soon then they fail the test and have to start all over.)
If not, then the flow appeared meager. Pity the pax in a crash with fire should that be all the water that is available.
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Given the fact that this was part of a test program, the rules aren't exactly the same.
 
Greg Bockelman said:
Given the fact that this was part of a test program, the rules aren't exactly the same.
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I have been with in 20" of the EA6B main mounts that had the fuse plug melt out, and that action isn't early as violent as that shown in the video.

The fuse plug is a antimony plug that melts and directs the tire N2 at the break, cooling it and preventing the fire.

that simply did not happen in the vid.
 
Like all tests, if the outcome had been known up front, no test would have been needed. It certainly appears that they were a little sanguine about the possibility of un unsuccessful test.

Sphincters in the cockpit were, one supposes, a little puckered, but it sounds as if they, at least, maintained their composure.

Bet it made for an interesting conversation during the post-test debrief, though!
 
Matthew said:
Yeah - I know the 777 was a PASS, I didn't realize the Airbus was a FAIL.

That's a pretty brutal test.
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If I recall correctly, the stop from V1 must be made without use of reverse-thrust, and with the engines still at takeoff power... can that be right, or am I (again) talking out of my a--?
 
from what I remember, the test is made at max gross weight (and perhaps even the MGW of the projected "stretched" versions), and at max possible abort speed (again for the "stretched" versions).

The idea is the test what happens when you make the brakes absorb the maximum amount of energy they are supposed to handle - the resulting heat should not cause a fire in a certain amount of time (the amount of time projected for ARFF to arrive).

I remember in the 777 test series the Chief test pilot was apparently caught unaware of the engineering decision to run the test at a higher weight and velocity in order to certify the brakes for the -300 as well as the -200 (or something like that).
 
SCCutler said:
If I recall correctly, the stop from V1 must be made without use of reverse-thrust, and with the engines still at takeoff power... can that be right, or am I (again) talking out of my a--?
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If by "still at takeoff power" you mean that the power is never reduced during the abort then that would be incorrect. I can't imagine any set of brakes stopping an airplane that is already at V1 if takeoff thrust continues to be applied. Heck, sometimes it's hard to hold the brakes at takeoff thrust on the runway or ramp starting from a standstill.
 
ScottM said:
That is what I was wondering. It seemed like everything was well scripted and planned for EXCEPT getting the stairs to the aircraft to get the crew out in the event of fire. Oops
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They were waiting for the Americans to liberate them.



Oops, this isn't the spin zone is it? :D
 
Everskyward said:
If by "still at takeoff power" you mean that the power is never reduced during the abort then that would be incorrect. I can't imagine any set of brakes stopping an airplane that is already at V1 if takeoff thrust continues to be applied. Heck, sometimes it's hard to hold the brakes at takeoff thrust on the runway or ramp starting from a standstill.
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Hence, my ab initio self-doubt. I should have done some research pre-post.

Sorry. (hangs head in shame)
 
kyleb said:
That AND I'd have expected that once they started applying water, they'd have used a widened spray pattern to knock down the heat, instead of a direct stream. The quantitiy of water available seemed pretty minimal too, given that a fire was a real probability in this test...

Of course, it's always easy to second guess.
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Kyle... I'd been thinking the same thing since watching the video.. fog versus straight stream... I was coming back to post this when I saw your comment on the issue

I never had ARFF training, but the concerns were the same as with semi-trailer/commercial vehicle wheel fires that I did train for long ago.

I cant help but think if the French ARFF guys CAUSED the "tire" explosions by using a straight stream. A fog pattern on the nozzle would have had a greater chance of evenly cooling the rim/tire/brake assembly, where a straight stream is very likely to cause a two piece wheel/rim assembly to cool unevenly, and therefore contract unevenly and even precipitate a failure from the uneven thermal stress.

Had it been a true over-heat, the fuse plugs would have gently deflated the tires. This looks like the guy with the hose made his own private hell underneath that aircraft, and had he been to the side of the wheel likely wouldn't have lived to tell about it.
 
Was there a treadmill involved in the tests?






:D
 
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