In the UK we replace them on the G109B at 3000 hours irrespective,
together with a few other mods which come up at that time. The new
pins have a better taper, handy if you rig frequently as I do, and are
replaceable without the major surgery reuired on the first occasion.
- Colin.

"Bob Jenneson" wrote:

Hi,
I am seeking advise on the replacement of the wing pins fitted in the
end of the spars on Grob 109 and 109B.
This also applies to the Grob Twin Astir.

A brief history.
These pins are welded to a plate that is glassed into the wing spar end
during manufacture. It was found out at a later time that some of these
assemblies were prone to cracking around the welds and required replacement
if found to be cracked.
In Australia we are required to "ultrasonic " test these pins every 500
hours ( AD 370 )
If tested 'OK' we keep flying.
We now have two aircraft that have 3000 hours each ( Life extension time )
and no cracks found.

Do we need to change the pins?

This is serious and expensive surgery and I am seeking advise as to how
other countries have dealt with this problem.
I understand that Australia in the only country that uses the ultrasonic
test.

Grob are happy to supply the new pin assemblies, but is it really necessary
if the old ones have a 3000 hour safe history.

Any help appreciated, Bob.