Wednesday, Feb 05, 2014 at 17:12
There are a few reasons that (mostly commercial) aircraft use
nitrogen.
1. It does not react volumetrically to changing air pressure due to altitude as much as plain air filled tyres, this prevents expansive blowouts at altitude, malformation of the tyre due to expansion, and auto deflation due to the tyre being expanded off the rim.
2.
Nitrogen is a natural fire suppressant which is a necessity to prevent a tyre fire on landing if something goes wrong. Many lower altitude aircraft are only required to have
nitrogen filled tyres on the braked wheels for this reason.
3.
Nitrogen, being inert, does not react with either the wheel or the tyre material.
4. Filling with
nitrogen from a bottle prevents the inadvertent use of locally compressed air which will likely contain moisture. Under extreme landing conditions such as a dragging brake, the tyre can heat to a point that the moisture turns to steam, thus expanding the tyre destructively.
Air that has been satisfactorily dried will not freeze at altitude or turn to steam on landing, so moisture content alone is not a valid reason for the use of
nitrogen in place of air.
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