Blanik Mandatory Bulletin No. L13/116a ?
On Mar 21, 8:26*am, Darryl Ramm wrote:
Its an eddy current test...
Darryl, I think Evan is right; this test is just conductivity between
two specified points. All it could possibly determine is the
resistance of the material, and cracks would have little effect on
that unless they were so bad that the wing would already have failed
under its own weight. The intent appears to be to collect information
that could provide data about alloy and temper.
The test points specified appear to be on the flange of the spar cap
angle near where it is riveted to the shear web. If I recall
correctly, the Blanik wing spar cap consists of that angle plus a
reinforcing strap riveted to the inner surface of one leg. At the
root, the forged steel attachment fitting is wedged between the angle
and the strap and secured to the two with rivets.
When the skin is later applied, some of those rivets that join the
steel fitting to the aluminum spar cap are drilled through along their
axes, and smaller rivets are driven through them to secure the wing
skin in that area. It is a pretty elegant system, since in theory the
shear strength of the two coaxial rivets is no less than that of a
single solid rivet. In practice, however, it makes for a complicated
assembly with many opportunities for errors and disruptions that can
compromise the structure.
Thanks, Bob K.
|