ASW 15 and concerns

Craig,

Tap inspection is used extensivly on composite structure from our
sailplanes to the newest Biz jets. The big difference is how hard you
need to tap! The best hammers are light aluminum on a piano wire, for
your case take a wood dowel (Pencel without an eraser) and bounce it
on the surface (in a pinch the edge of a quarter works well). You
will hear a dull sound if there is any disbond between the skin and
core. Try to find an area like the spar where you have a transition
and listen to the chenge in sound, this will give you the idea. With
experiance this is a very good test, but it is best to have some
experinace on a know structue with flaws. If you have a major concern
find an inspector who has experinace with an ultrasound unit. In
areas that do not have core (or a thin core) wait until night and put
a bright light behind the structure. If an area is damaged (Disbond
in the layup) you will see a shadow. Paint and filler complicate this
inspection.

Harry L. Clayton
Sr. Research Engineer NIAR

On Apr 11, 7:48 pm, wrote:
..
I had someone reccommend doing a "TAP TEST" on the structure to listen
for inconsistant sounds indicating problems within. Esp. in regard to
the balsa core and the wood construction? I know all about the spar
rot thing, but what about the rest of the plane?

Thanks
Craig