Grob 109 wing pins

In the US, AD 90-02-09 required replacement of the Wing Spar Spigot pins
within 500 flights of the AD, even if no cracks were found on ultrasonic
inspections. At least for the Grob 103 Twin Astir and 103 variants. So most
of that work was completed in 1990-1991. Or Grob 103 Twin II completed the
3000hr life extension inspection a few around the year 2000. The pins had
been replaced in 1991.

If your AD allows repeated inspections, why replace the spigot pins?

BT

"Bob Jenneson" wrote in message
...
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.