A preventable incident
The right horizontal fell off in flight...
A rare survivor of the loss of 1/2 the horizontal..
The cause of the loss was a very light scoring of the outer fibers of the
top of the right horizontal when the Monokote covering was cut back to provide
a gluing surface to the fuselage. Over a series of "energetic" flights the
scoring created a "stress riser" in the outer fibers which grew to permit the
entire right side to collapse downward under extreme flight loads.
Surprisingly the loss wasn't noticed immediately, but only after some time had passed.
The plane was landed without any problems.
Upon inspection of the parts, it was obvious the entire right side had failed downwards
along the line the knife cut in the top fibers.
Repair consisted of reinstalling the broken part, with epoxy as adhesive, adding a tubing
brace from 3/4 span on the horizontal to the fuselage centerline on the bottom, and over
to the 3/4 span point on the left side. A 1/2" balsa tri-stock wedge was epoxied on the
top of the break.
Subsequent flights went well.
wackobreak1.htm.....04-04-2004
wackobreak1.htm
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