Will, and others,
The play is because the black pins are undersized about .007 I think.
The main pip pin is about .499 so only a tiny amount of play is
available.
Normally, the oversized bushes allow what appears to be excessive play
when the wings are not rigged. When the plane is rigged, those sloppy
bushes get hard to align unless you were superman during the cockpit
module build up and got the fuselage and wing bushes just perfect. I
only have two aircraft that align so well, the wing pins slide in
easily, but that is only at 85 degrees and with the tips held just
right. Hotter or colder, or with an untrained assistant, it is tougher
to push the pins in. So what to do?
Since none of us is superman, I many times have re-aligned the bushes on
final wing rigging by heating my spare tapered black pin until just too
hot to touch, but not sizzle (180F), and ram it home. Let it set
overnight and the three bushes get aligned. Once in a while, I do have
to put my 1/2 inch reamer into the pilot side hole and knock a
thousandth off for a nice hand fit of the pip pin because of the tighter
tolerances.
Note: There is a good reason for using the pip pin when doing spar
alignment, especially on the glider wing retrofit. Unfortunately we
don't have the luxury of setting our own bushes with the short wings.
If we follow the instructions blindly and use just the bolts, you won't
quite get perfect alignment. So just heat the pin and help the bushes
align.
Please do not overheat your existing wing pin and destroy the heat
treating. At 6 Gs, you would not believe the shear load on that pin.
So don't rip everything out just yet, try a bit of heat and patience.
It's worth it.
Regards,
Bud Yerly
----- Original Message -----
From: William Daniell<mailto:wdaniell@etb.net.co>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Monday, January 17, 2011 8:19 AM
Subject: Europa-List: Main wing bushings
For the assembled wisdom
I have a little slop in the main spar pins when I put them into each
bushing separately - "a little slop" means when I wiggle the spar pins
the ends move about 1/32.
There is no slop when the whole thing is assembled and the pins are a
light push fit.
Is this normal?
Will
http://www.matronics.com/Navigator?Europa-List<http://www.matronics.com/N
avigator?Europa-List>
http://www.matronics.com/contribution<http://www.matronics.com/contributi
on>
|