Grob 102 Astir-CS rigging adjustment solution

[cloud-dancer]

I was wanting to find out from any other 102 owners what steps they
may have taken in dealing with the bottoming out of the rotating
locking sleeve collar for the four wing lock-up connections on an
Astir-CS.

The handbook showed the optimum range of lock-up travel for the collar
but did not address how to remedy when it rotates around too far.

I first tried rotating the bar (3 complete revolutions) to the
opposite side as lock-up was only 1/3 travel into the pin's groove in
the collar on that side but this made no difference. I stopped when
the threaded tube ends became too minimal on one side and protruding
too far on the other to continue.

I contacted Grob for replacement balls for each of the 6 for the two
placements on that side and have some coming that are .05mm larger
diameters than the originals (anything larger will have to be ordered
from Germany).

--Has anyone dealt with this problem before on a 102 CS?
--Did rotating the bar make any changes in the collar rotation on the
side that bottomed out?
--If you went to larger balls, how much of an increased diameter was
necessary to fix the problem?
--Is the shaft designed to bottom out against the cross-pin in the
tube with the balls locking against the inboard taper of that channel?
--any suggestions on getting proper alignment on the dual thread
arrangement when putting it back together?

This matter has held up my annual for several weeks now and left me
out of commission until this is satisfactorily resolved.

Thanks for any comments and help regarding this.

Cloud-Dancer

[Jjglider]

Yo Cloud-Dancer,
Rotating the bar will do nothing to help the "bottoming out" problem, It
will however move the "tram" of your wings. By rotating the bar three
revolutions, you have kicked one wing Aft and the other Forward. Recommend you
take the three revolutions out and then "check the tram" by measuring from the
aileron cutout to a common point on the vertical fin (TE hole works well).
Further adjustment may be called for, Use a steel tape.
Larger balls is the fix (I wish we could all order some of those) and they
seat on both sides of the groove in the lift fitting that is sticking out of
the wing.
Give me a shout if this doesn't make any sense, JJ USA

[Jjglider]

It is important to check that ALL THE BALLS are properly seated after
assembling any of Grobs stuff. Have a helper pull Forward on the left wing as
you tighten the collars on the left side, Now have your helper pull Aft and try
and tighten the collars again. Repeat this procedure for the right wing.
Over the years, If you fly around with LOOSE BALLS, you may get a condition
known as WORN BALLS, this may lead to DEFORMED BALLS as a direct result of
SLAMMING YOUR BALLS against the walls of your grooves.
Worn or deformed BALLS require NEW BALLS and you don't want to know how much
fun it is getting them in there. So TIGHTEN UP YOUR BALLS and you won't need
NEW BALLS even though most of us would like to get LARGER BALLS if all we had
to do was order them from Grob.
JJ USA

[Jean Richard]

Jjglider a écrit :

>
> It is important to check that ALL THE BALLS are properly seated after
> assembling any of Grobs stuff. Have a helper pull Forward on the left wing as
> you tighten the collars on the left side, Now have your helper pull Aft and try
> and tighten the collars again. Repeat this procedure for the right wing.

A few years ago, I have been flying in a club where a G103 had a problem
opposite to bottoming of the sleeve. It was just a few mm in the slot (the
minimum being 5 mm).

What I didn't like was the fact that we had to tighten the sleeve every two or
three flights. Only the front bar sleeves needed to be thighten so often.
The two other ones were ok. Any idea of the problem ? Derigging and rerigging
didn't change anything.

That G103 had approximatly 2000 hours.

Jean

[Jjglider]

Hi Jean, (not hygiene)
I'm not sure about the condition that you describe, it may be that the
forward balls have been replaced at some time . It leads you to think the balls
are hitting on only one side of the groove. The wing fitting should go all the
way into the fuselage fitting and seat when the end of the fuselage pipe hits
the base of the wing shaft. If for some reason, the fuselage pipe is holding
the shaft too far out, then grinding off about 1/32 " from the end of the pipe
would be a good test.
I would also check the "tram". If way out of whack, at some point the
misaligned rear drag fitting will start to hold the forward fitting out (keep
the fitting from sliding home). Check this before grinding.
When JJ Glider Repair was in business, we would always say "burnish the
fitting" and would never say "grind off something"
JJ USA