Re: Causes and solutions for window crazing.

From:         Alun Jenkins <alunj@dial.pipex.com>
Organization: Jenisys Ltd
Date:         05 Aug 96 23:32:58 
References:   1 2
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Hi,
I used to work for BA in their 747 Mtce depot. We removed the windows and
polished them to make them clear again.  I think that the crazing is mainly
on the surface and does not impact safety at all. Therefore polishing them
is mainly a cosmetic operation. (And a costly one at that, to remove the
panes you need to stip out the cladding inside and remove about 10 Bolts,
there is also a risk that they wont be reseated correctly or wiring my be
nicked.) Each time they are removed they are measured to make sure they
are not too thin!.  I was told that the crazing was caused by H2S04
(Sulphuric Acid) formed by the Sulpher Dioxide ejected from volcanic
eruptions.

BTW When I worked for BA we used to polish the whole plane, front to back
with aeroclean (T-Cut for aircraft). I think we found that this actually
improved the economy of the aircraft (smoothing the surface) and the
customers really liked getting a nice shiny 'plane back.

When airlines do a paint Job they usually remove the panes, although this
does not seem to always be the case.

Alun