Kelvin,
It is nice to hear that you installed your glass trouble free. Trim, fit,
practice
the install and properly block it to get an even bond and it lays fairly
nice. A slight gap that is filled with Redux between the glass and skin rarely
will leave a crack, but there will be a hump or a lot of blending for a truly
fine show finish. If you leave a trough or sharp ridge, the filler may crack
due to material expansion/change.
The slight miss match in height is due to the newer slightly thicker glass we
have
now. I normally use expand cell and patience. The windscreen and doors rarely
crack around the joint rim when filled up on to the glass then covered with
good 2 part urethane. If the glass has no filler sometimes there is a bit
of a transition hump or ridge.
For only those who want a very smooth job and or have used the optional 1/4 inch
windscreen: The use of 2 oz glass over the initial fill will allow a smoother
finish and less of a chance of cracking of the extra filler. This same
technique
can be used to HELP prevent cracking at the spar and wing fillet walkway
(or butt seat area) of the trigear. In the area of the leading edge between
the root rib and first rib forward of the spar of the XS flexes under "butt"
pressure on trigear ingress gymnastics. Glass over the filler can help. I've
used carbon fiber layers and standard Rutan 7725 Bid to try to prevent this but
the area near the spar will flex and a filler crack can happen. Document it
to appease inspectors.
Why worry about the cracks: In selling a used aircraft, the new owner and more
importantly the new inspector/repairman, will question the crack and then want
to grind out, inspect and fix any cracks, thereby decreasing your resale value.
Best Regards,
Bud Yerly
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