To level the top wing, a string is
taped from the end of the wing, on the trailing edge, to the other end
of the wing on the trailing edge. Judy Smith is pointing to this
line. Next
a line level is placed on the line. It is very important to ensure
that the line level is exactly in the center of the line so that gravity
is pulling on the ends exactly or the level will be off. Again we
are using a bubble level and you know what I think of that. I believe
that the best method for all of these measurements would be to use a laser
level from a fixed reference point in the hanger. This would ensure
that all measurements are exact. You could use a smart level as a
secondary check.