Re: B747 technical questions

Date:         06 Aug 97 01:49:31 
From: (C. Marin Faure)
Organization: Northwest Nexus Inc.
References:   1 2 3 4 5 6 7
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In article <airliners.1997.1672@ohare.Chicago.COM>, wrote:

> Michel Gammon wrote:
> > My guess for the reason for nitrogen instead of air is that nitrogen is
> > inert.  During an emergency stop before V1 when maximum braking is used, I
> > suspect the internal tire temperatures can get very high (the external
> > surface will at least be afforded some air cooling, while the gas in the
> > tire will be insulated from external air and thus will not be cooled).

During an emergency stop, the tires can get so hot that they will explode
no matter what they're filled with.  The effect of a 747/777 tire
exploding is identical to the detonation of a 500 pound bomb.  For this
reason, the wheels are fitted with fuse plugs which melt at a specific
temperature and let the air/nitrogen/whatever out of the tire before it
explodes.  In the film we have of the 777's max gross weight RTO (refused
takeoff) test you can clearly see the fuse plugs squirting out of the
wheel followed by a big puff of smoke as the tire begins to deflate.

C. Marin Faure
  author, Flying A Floatplane