DuoDiscus Wing

Enough time has past such that several DuoDiscus wings must have been
inspected. However, there have been no reports as to what was found during
the inspection or what, if anything had to be done. All owner should
communicate with each other so that we all can have a better handle on what
is happening to the fleet. I would like to request that all owners provide
the following information when available. It would be appropriate to obtain
data for all ships; those that passed and those that failed.
1) Serial Number
2) Any problems doing the inspection
3) Results of the inspection
4) What repairs, if any, were required
5) Cost or reimbursement from Schempp-Hirth
6) Any other info that you would care to share.

Some voids were found in the spar of the ship that I am involved with (S/N
217). In one spot a wire could be inserted for what appeared to be the full
width of the spar cap. The ship was transported to M & H for a "second
opinion" and any repairs as required. I will provide additional info when
the ship is returned home.

Duane

In article 3fRab.527488$uu5.88216@sccrnsc04,
says...
Enough time has past such that several DuoDiscus wings must have been
inspected. However, there have been no reports as to what was found during
the inspection or what, if anything had to be done. All owner should
communicate with each other so that we all can have a better handle on what
is happening to the fleet. I would like to request that all owners provide
the following information when available. It would be appropriate to obtain
data for all ships; those that passed and those that failed.

There is a thread on www.gliderforum.com under the Duo Discus section
about this that might contain some of what you are after.
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directly

Eric Greenwell
Richland, WA (USA)

I am not involved with a duo but of the three inspected so far by our local
repair shop all required repairs, a 4th has still to be inspected.
gary
"Duane Eisenbeiss" wrote in message
news:3fRab.527488$uu5.88216@sccrnsc04...
Enough time has past such that several DuoDiscus wings must have been
inspected. However, there have been no reports as to what was found
during
the inspection or what, if anything had to be done. All owner should
communicate with each other so that we all can have a better handle on
what
is happening to the fleet. I would like to request that all owners
provide
the following information when available. It would be appropriate to
obtain
data for all ships; those that passed and those that failed.
1) Serial Number
2) Any problems doing the inspection
3) Results of the inspection
4) What repairs, if any, were required
5) Cost or reimbursement from Schempp-Hirth
6) Any other info that you would care to share.

Some voids were found in the spar of the ship that I am involved with (S/N
217). In one spot a wire could be inserted for what appeared to be the
full
width of the spar cap. The ship was transported to M & H for a "second
opinion" and any repairs as required. I will provide additional info when
the ship is returned home.

Duane

I would like to request that all owners provide
the following information when available. It would be appropriate to
obtain
data for all ships; those that passed and those that failed.
1) Serial Number
2) Any problems doing the inspection
3) Results of the inspection
4) What repairs, if any, were required
5) Cost or reimbursement from Schempp-Hirth
6) Any other info that you would care to share.

Duane


Some have responded directly to me. The info is appreciated, However ....
Actually I was not trying to collect info just for me. I was hoping that
the info would be posted to the Group so that owners around the world would
also know what is being found and be better able to evaluate their Duo.

Duane

"Duane Eisenbeiss" wrote in message
news:3fRab.527488$uu5.88216@sccrnsc04...
Enough time has past such that several DuoDiscus wings must have been
inspected. However, there have been no reports as to what was found
during
the inspection or what, if anything had to be done. All owner should
communicate with each other so that we all can have a better handle on
what
is happening to the fleet.
Duane

The report for the inspection of ship S/N 217 has been received. The left
wing had 1 small void. The right wing had 4 small voids.

Has anyone had an inspection that revealed large voids? say larger than 12
inches or 30 cm.

Duane

One here in NZ had a void of 14-15 inchs long,the engineers here think
the problem has been from making the glue mixture to thin and it has just
flowed out of the rear side as there is a ridged edge on the front side to
make all the mix go towards the rear.
One comment made was they thought that the factory had attempted to
push some mix into that void by hand by reaching through the access point
but had only been partially successful
gary
"Duane Eisenbeiss" wrote in message
news:rQDhb.533114$Oz4.430152@rwcrnsc54...

"Duane Eisenbeiss" wrote in message
news:3fRab.527488$uu5.88216@sccrnsc04...
Enough time has past such that several DuoDiscus wings must have been
inspected. However, there have been no reports as to what was found
during
the inspection or what, if anything had to be done. All owner should
communicate with each other so that we all can have a better handle on
what
is happening to the fleet.
Duane

The report for the inspection of ship S/N 217 has been received. The left
wing had 1 small void. The right wing had 4 small voids.

Has anyone had an inspection that revealed large voids? say larger than
12
inches or 30 cm.

Duane

"goneill" wrote in message ...
One here in NZ had a void of 14-15 inchs long,the engineers here think
the problem has been from making the glue mixture to thin and it has just
flowed out of the rear side as there is a ridged edge on the front side to
make all the mix go towards the rear.
One comment made was they thought that the factory had attempted to
push some mix into that void by hand by reaching through the access point
but had only been partially successful
gary
************************************************** ********************************

It would be interesting to know if there is a commonality between all
of these discrepancies. Was the bonding paste always too thin or did
they mix it according to the clearances of each wing? If the mixture
really was too thin causing a void of 14-15 inches long then there are
probably many other voids which can't be seen on video. There needs
to be an ultrasonic inspection procedure developed which can map the
bonding interface.

"Slingsby" wrote in message

It would be interesting to know if there is a commonality between all
of these discrepancies. Was the bonding paste always too thin or did
they mix it according to the clearances of each wing? If the mixture
really was too thin causing a void of 14-15 inches long then there are
probably many other voids which can't be seen on video. There needs
to be an ultrasonic inspection procedure developed which can map the
bonding interface.


I have no first hand knowledge. Talked to the owner of a well known,
respected composite repair shop who said that cotton threads are added to
the epoxy to thicken it and keep it from running. And that apparently they
had failed to add enough cotton fiber and this resulted in epoxy running
out, creating the voids.

--
bumper - ZZ
"Dare to be different . . . circle in sink."
to reply, the last half is right to left


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"John Morgan" wrote in message ...
"Slingsby" wrote in message

It would be interesting to know if there is a commonality between all
of these discrepancies. Was the bonding paste always too thin or did
they mix it according to the clearances of each wing? If the mixture
really was too thin causing a void of 14-15 inches long then there are
probably many other voids which can't be seen on video. There needs
to be an ultrasonic inspection procedure developed which can map the
bonding interface.


I have no first hand knowledge. Talked to the owner of a well known,
respected composite repair shop who said that cotton threads are added to
the epoxy to thicken it and keep it from running. And that apparently they
had failed to add enough cotton fiber and this resulted in epoxy running
out, creating the voids.

According to the DG website the bonding paste should be about as thick
as cake icing. I suppose too much cotton would also weaken the bond
as cotton fibres aren't as strong as epoxy. I still believe that if
there are voids which can be seen and can have wires poked into them
then there must also be voids which can't be seen and are far to thin
to allow wire into them. A .0005 to .008mm thick gap between the spar
cap and shear web could not be seen on a video but it would still be
an area where there is no bond. Ultrasound would still reflect off of
the interface and show a gap. The ultrasonic technique would need to
be proven and calibrated on actual wings where voids have been found.
Filling the voids immediately makes the chances of developing another
inspection method unlikely.

On 14 Oct 2003 22:56:24 -0700, (Slingsby)
wrote:

"John Morgan" wrote in message ...
"Slingsby" wrote in message

It would be interesting to know if there is a commonality between all
of these discrepancies. Was the bonding paste always too thin or did
they mix it according to the clearances of each wing? If the mixture
really was too thin causing a void of 14-15 inches long then there are
probably many other voids which can't be seen on video. There needs
to be an ultrasonic inspection procedure developed which can map the
bonding interface.


I have no first hand knowledge. Talked to the owner of a well known,
respected composite repair shop who said that cotton threads are added to
the epoxy to thicken it and keep it from running. And that apparently they
had failed to add enough cotton fiber and this resulted in epoxy running
out, creating the voids.

According to the DG website the bonding paste should be about as thick
as cake icing. I suppose too much cotton would also weaken the bond
as cotton fibres aren't as strong as epoxy. I still believe that if
there are voids which can be seen and can have wires poked into them
then there must also be voids which can't be seen and are far to thin
to allow wire into them. A .0005 to .008mm thick gap between the spar
cap and shear web could not be seen on a video but it would still be
an area where there is no bond. Ultrasound would still reflect off of
the interface and show a gap. The ultrasonic technique would need to
be proven and calibrated on actual wings where voids have been found.
Filling the voids immediately makes the chances of developing another
inspection method unlikely.

Two comments:

- viscous, sticky stuff like epoxy will tend to leave a larger void or
none at all. I think a series of deeper bubbles would be far more
likely than a single sub 0.1mm area.

- it would be extremely difficult to get epoxy into a very narrow void
unless it was rather thin

Does anybody on here know what advantage cotton threads would have
over, say, microballoons or separated glass rovings?
--
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gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :