Grob Astir AD spar spigots

On Apr 20, 7:44 am, wrote:

I saw a reference to a repair team in one of Bob Kuykendall's posts, a
team that did the 103's, but I suppose those were Grob guys Bob?

Gosh, it's been like a dozen years, I don't remember that much about
it. But as I recall it, it _was_ a team sent around by Grob, they'd
lined up several aircraft each at several shops around the country and
did a grand tour. I saw them briefly, I think at Steve Brown's Bay
Area Composite Repair.

As I recall the repair involved cutting through the spar stub shear
web to liberate the chunks of plywood to which the spigot was bolted
or riveted, leaving an ugly rectangular notch at the end of the stub
but not removing material from the spar caps. The beefier replacement
spigot and its support (probably plywood, but perhaps prefabbed
fiberglass plate, I don't recall) was placed into this notch, aligned
with a fixture that the team had brought with them, and floxed into
position. After the flox cured, the spigot and its support was secured
with several shear wraps of cloth. I don't recall if they ground away
the original shear wraps; they might have done so to keep the spar
stub within its original envelope.

As an aside, this series of repairs is one of the events where I first
started to comprehend that there's no particular magic to composite
aircraft structure. I remember spending quite a while looking at one
of the cut-open aircraft under repair after the guys had knocked off
for the day. I don't remember much of what I saw, but I do remember
thinking "What, is this all there is?" Of course, there's a lot of
careful engineering to it, engineering that I'm not qualified to
practice or for some of it to even understand. But I think that a lot
of it is just a mix of common sense plus stuff that people tried and
tested and found to work sufficiently, and the engineering came later
to figure out _why_ it worked.

Thanks, Bob K.