Discus CS grounded in France

[Marc Till]

French aviation authorities (DGAC) have just grounded the Discus CS,
because of an in-flight wing failure :
http://195.68.62.11/GSAC/ad_cns.nsf/vwCNsTelegraphiques?OpenView

Apparently, it is not the case in Germany (nothing on the Schempp-Hirth
or LBA websites)

Has anyone got more news ?

Cheers

Marc TILL
Orsay, France
http://perso.club-internet.fr/mtill/
http://www.planeur-chartres.org/

[Guy Byars]

> I heard it was a high time glider in severe turbulence.

And that makes it ok?

[George William Peter Reinhart]

Yep,
Makes you wonder doesn't it?
Where are the cut offs for High Time and "severe " turbulence that would
make it not OK to fly?
Currently flying a well aged Nimbus with over 1000 hours on it.
Should I be worried about my personal safety because of the airframe hours?
Are there some days I just shouldn't fly because the "turbulence" might be
"too high"?
All advice carefully considered.
Cheers!


Guy Byars > wrote in article
>...
>
>
> > I heard it was a high time glider in severe turbulence.
>
> And that makes it ok?
>
>
>

[Mark Zivley]

The wording in the english version of the French document says that
there was separation of the wing in normal operation with some
indication of a possible manufacturing defect.

Now, this may turn out to not be true, but if it is true this won't be good.

Thomas Knauff wrote:
> I heard it was a high time glider in severe turbulence.
>
> Tom Knauff
>
>
> "Marc Till" ]> wrote in message
> ...
>
>>French aviation authorities (DGAC) have just grounded the Discus CS,
>>because of an in-flight wing failure :
>>http://195.68.62.11/GSAC/ad_cns.nsf/vwCNsTelegraphiques?OpenView
>>
>>Apparently, it is not the case in Germany (nothing on the Schempp-Hirth
>>or LBA websites)
>>
>>Has anyone got more news ?
>>
>>Cheers
>>
>>Marc TILL
>>Orsay, France
>>http://perso.club-internet.fr/mtill/
>>http://www.planeur-chartres.org/
>>
>
>
>

[Chris OCallaghan]

Per the French Airworthiness Directive, "separation of the wing during
normal operating conditions, possibly the result of a manufacturing
defect."


Marc Till ]> wrote in message >...
> French aviation authorities (DGAC) have just grounded the Discus CS,
> because of an in-flight wing failure :
> http://195.68.62.11/GSAC/ad_cns.nsf/vwCNsTelegraphiques?OpenView
>
> Apparently, it is not the case in Germany (nothing on the Schempp-Hirth
> or LBA websites)
>
> Has anyone got more news ?
>
> Cheers
>
> Marc TILL
> Orsay, France
> http://perso.club-internet.fr/mtill/
> http://www.planeur-chartres.org/

[Guy Byars]

I better check the spar splices in the 1-20 wing again! With a red line of
75mph, you can't be too careful.


> Same happens as with a wooden glider.......
>
> SF.

[Jim Vincent]

>
>Same happens as with a wooden glider.......
>

JJ knows that...after all, wood and fiberglass are both composite aircraft;-)

Jim Vincent
CFIG
N483SZ

[George William Peter Reinhart]

Ian,
I've got a copy of the same articles.
I used to think my Mooney was a pretty high time at 7200 hours until I
parked it next to the sister ship with 4200+ hours.
There is still the "turbulence" though, so I'm wondering if I should fly
only on days when there is no lift.
Cheers! (and still trolling)

tango4 > wrote in article
>...
> I have a copy of Technical Soaring, the July 2002 vol 26 number 2 that
> discusses lifetime predictions of compostie aircraft. The general
> conclusions seem to be that "lifetimes far in excess of the current 12000
> hours" and "a lifespan of 50000 ( yes fifty thousand ) hours with a high
> level of safety" so your 1000 hour Nimbus is hardly out of the running in
> period!
>
> Ian
>
>
> "George William Peter Reinhart" > wrote in message
> ...
> > Yep,
> > Makes you wonder doesn't it?
> > Where are the cut offs for High Time and "severe " turbulence that
would
> > make it not OK to fly?
> > Currently flying a well aged Nimbus with over 1000 hours on it.
> > Should I be worried about my personal safety because of the airframe
> hours?
> > Are there some days I just shouldn't fly because the "turbulence" might
be
> > "too high"?
> > All advice carefully considered.
> > Cheers!
> >
> >
> > Guy Byars > wrote in article
> > >...
> > >
> > >
> > > > I heard it was a high time glider in severe turbulence.
> > >
> > > And that makes it ok?
> > >
> > >
> > >
>
>
>

[Eric Greenwell]

In article >,
says...
> >
> >Same happens as with a wooden glider.......
> >
>
> JJ knows that...after all, wood and fiberglass are both composite aircraft;-)

Not really. Wood is a material used "as is", while composite aircraft
mix at least two materials together; e.g., epoxy and fiberglass.
Gluing or bolting materials together doesn't qualify as "composite".

You probably knew that...
--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly

Eric Greenwell
Richland, WA (USA)

[tango4]

Ahhh, now that is a completely different question. The material will last a
long, long time but if they haven't put any in the structure then all bets
are off!

Ian


"JJ Sinclair" > wrote in message
...
> Ian wrote>>>>>>>>>>>>>>>>>>>>>>>> a lifespan of 50000 ( yes
fifty
> thousand ) hours with a high
> >level of safety" so your 1000 hour Nimbus is hardly out of the running in
> >period!
>
> But what if they didn't use enough glue?
>
> JJ Sinclair

[CH]

it looks a bit suspicious that the latest incidents
concerned gliders out of Schemp Hirth's Chechia
licence fabrication only.
CH

----- Original Message -----
From: "Chris OCallaghan" >
Newsgroups: rec.aviation.soaring
Sent: Wednesday, September 10, 2003 12:29 AM
Subject: Re: Discus CS grounded in France


> Per the French Airworthiness Directive, "separation of the wing during
> normal operating conditions, possibly the result of a manufacturing
> defect."

[Ray Lovinggood]

Eric,

Concrete and steel bonded together consitute a 'composite'
structure. Steel girders used for bridges have steel
studs welded on top flanges of the girders. The concrete
deck is poured and bonds to the girders with the help
of the numerous studs. The Portland cement in the
concrete is the glue which makes the bonding possible.
So, in a way, the concrete and the steel are 'glued'
to each other. Calculating the strength of the structure
takes the 'composite' structure into account.

Ray Lovinggood
Carrboro, North Carolina, USA

At 02:42 10 September 2003, Eric Greenwell wrote:
>In article ,
says...
>> >
>> >Same happens as with a wooden glider.......
>> >
>>
>> JJ knows that...after all, wood and fiberglass are
>>both composite aircraft;-)
>
>Not really. Wood is a material used 'as is', while
>composite aircraft
>mix at least two materials together; e.g., epoxy and
>fiberglass.
>Gluing or bolting materials together doesn't qualify
>as 'composite'.
>
>You probably knew that...
>--
>!Replace DECIMAL.POINT in my e-mail address with just
>a . to reply
>directly
>
>Eric Greenwell
>Richland, WA (USA)
>

[F.L. Whiteley]

Discussed this years ago in the UK, we concluded WRT
overloading/overstressing that

1. metal bends and fatigues and shows signs of cracking. Fatigue life can
be estimated.
2. wood fails progressively with audible and visible cracking, though glue
joints are something else (there's an English pub discussion about why the
lengthwise cracked beams in the old pubs are stronger than solid beams.
Turns out that cracks indicated that the wood was seasoned, therefore
stronger in a load bearing sense. Wood without cracks was green, though
more resilient to impact, was more flexible and resulted in more bending
under load which apparently had resulted in some pub collapses, or at least
the story goes. This was all discussed in a pub in East Anglia where it was
said to actually have been built on a large raft in a boggy area a few
hundred years earlier.) Wood has theoretically infinite life, or at least
that was assumed.
3. composites (in the common sense) fail catastrophically (ever seen what
happens when a fiberglass pole vault goes bad?, similar to twisting a wing
section off I'd imagine, whether through overstress or defect.)

BTW, your 2c is probably not one of the earlier heavies mentioned. I think
most were 2b's. 1000 hours was 1/3 of the initial service life of the first
generations of glass ships, based on 1/6 of a design life of 18,000 hours as
a conservative estimate. Subsequent studies have shown long composite life,
though some of the metal bits may need periodic crack testing and
replacement. 2c is not really first generation glass, but still in the
early carbon fiber period. Not sure what the initial service life SH might
have assigned, but expect it would have been at least 3000 hours.

Frank Whiteley

"George William Peter Reinhart" > wrote in message
...
> Oops!!!
> Should have been _forty two thousand_ hours on the Mooney sister ship.
> At 7200 hrs, mine had used up four engines.
> No telling how many on the sister ship.
> Cheers!
>
> George William Peter Reinhart > wrote in article
> >...
> > Ian,
> > I've got a copy of the same articles.
> > I used to think my Mooney was a pretty high time at 7200 hours until I
> > parked it next to the sister ship with 4200+ hours.
> > There is still the "turbulence" though, so I'm wondering if I should fly
> > only on days when there is no lift.
> > Cheers! (and still trolling)
> >
> > tango4 > wrote in article
> > >...
> > > I have a copy of Technical Soaring, the July 2002 vol 26 number 2 that
> > > discusses lifetime predictions of compostie aircraft. The general
> > > conclusions seem to be that "lifetimes far in excess of the current
> 12000
> > > hours" and "a lifespan of 50000 ( yes fifty thousand ) hours with a
> high
> > > level of safety" so your 1000 hour Nimbus is hardly out of the running
> in
> > > period!
> > >
> > > Ian
> > >
> > >
> > > "George William Peter Reinhart" > wrote in message
> > > ...
> > > > Yep,
> > > > Makes you wonder doesn't it?
> > > > Where are the cut offs for High Time and "severe " turbulence that
> > would
> > > > make it not OK to fly?
> > > > Currently flying a well aged Nimbus with over 1000 hours on it.
> > > > Should I be worried about my personal safety because of the airframe
> > > hours?
> > > > Are there some days I just shouldn't fly because the "turbulence"
> might
> > be
> > > > "too high"?
> > > > All advice carefully considered.
> > > > Cheers!
> > > >
> > > >
> > > > Guy Byars > wrote in article
> > > > >...
> > > > >
> > > > >
> > > > > > I heard it was a high time glider in severe turbulence.
> > > > >
> > > > > And that makes it ok?
> > > > >
> > > > >
> > > > >
> > >
> > >
> > >
> >

[Eric Greenwell]

In article >,
says...
> Earlier Eric wrote>>>>>>>>>>>>>>>>>>
> >Not really. Wood is a material used "as is", while composite aircraft
> >mix at least two materials together; e.g., epoxy and fiberglass.
> >Gluing or bolting materials together doesn't qualify as "composite
>
> But Eric, How about the plywood that we use in our wooden gliders? Doesn't that
> qualify as a composie? I like to think that Howley Bowlus was the first to use
> modern composite techniques when he laid 3 very thin sheets of mahogany veneer
> into a concrete mold. These sheets were laid in at 45 degrees to each other
> with glue between each. I believe he also added some heat bafore the male plug
> was forced into the female mold.

What you describe is a molding technique using distinct pieces of
wood, not composite materials. Molding is not a new idea, of course.

Is plywood defined somewhere as a composite? To me, it's not a
composite because it's just one material, glued together in distinct
layers, not in a matrix like fiberglass and epoxy.

--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly

Eric Greenwell
Richland, WA (USA)

[Eric Greenwell]

In article >,
says...
>
> Concrete and steel bonded together consitute a 'composite'
> structure. Steel girders used for bridges have steel
> studs welded on top flanges of the girders. The concrete
> deck is poured and bonds to the girders with the help
> of the numerous studs. The Portland cement in the
> concrete is the glue which makes the bonding possible.
> So, in a way, the concrete and the steel are 'glued'
> to each other. Calculating the strength of the structure
> takes the 'composite' structure into account.

I wouldn't call this a composite structure, because the materials are
basically separate with a definite interface (the studs). I do think
of concrete reinforced with iron bar and/or or iron grid as a
composite.

--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly

Eric Greenwell
Richland, WA (USA)

[Chuck Scrivner]

test

[F.L. Whiteley]

"Roy" > wrote in message
...
> When getting antsy about composite life it's worth remembering helicopter
> rotors are similar in construction to our ships and have service life on
the
> main rotor of 15 years +
> (I suspect life of the aircraft but 1 I know in particular had 15+ years
and
> 000's of hours on)
> this is in a particularly harsh environment,
> Failures, I suspect have more to do with poor initial construction and or
> abuse rather than "lifeing" the items.
>
> my $0.02
>
> (and belive me, I do have the flameshields UP)
>
>
Reminds me of the rotor blades I saw that had been wrapped around a tree in
about 1970. Steel strap inside balsa laminates with fiberglass cover and
shielded leading edge. Pretty amazing.

I have no doubts about the integrity of properly constructed composite
structures. There have been some suggestions that at least one company may
have been a bit heavy handed with the squeegees a few years ago on one
model, as the airfoil was losing shape after three years. Current pre-pregs
have improved lay-up quality in many areas, but sloppy joinery, well.......

Frank Whiteley

[Eric Greenwell]

In article >,
says...
> Eric Greenwell > wrote in message >...
> > In article >,
> > says...
> > > >
> > > >Same happens as with a wooden glider.......
> > > >
> > >
> > > JJ knows that...after all, wood and fiberglass are both composite aircraft;-)
> >
> > Not really. Wood is a material used "as is", while composite aircraft
> > mix at least two materials together; e.g., epoxy and fiberglass.
> > Gluing or bolting materials together doesn't qualify as "composite".
> >
> > You probably knew that...
>
> Webster's says:
>
> Main Entry: 1com·pos·ite
> Pronunciation: käm-'pä-z&t, k&m-', esp British 'käm-p&-zit
> Function: adjective
> Etymology: Latin compositus, past participle of componere
> Date: 1563
> 1 : made up of distinct parts:
>
> That would seem to encompass gluing materials together. But of course
> you know better. You might want to send a note to the folks at
> Websters.

I doubt that Websters is interested in my understanding of
"composite" as used in the aircraft field, and general dictionaries
are a poor place to discover the meaning and usage of technical terms;
in this case, what a composite material is.

I am interested in how people that do work in the field use the term.
All aircraft are "composite" according to Webster's definition, but
what we are talking about is aircraft built from "composite"
materials. We all agree that fiberglass, carbon, Kevlar, etc. cloth
with epoxy make a composite material, but plywood? I don't think it
is, but I'm interested in why others think it should be included as
such with fiberglass and epoxy structures.
--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly

Eric Greenwell
Richland, WA (USA)

[JJ Sinclair]

Earlier Reic wrote>>>>>>>>>>>>>>>>
>Is plywood defined somewhere as a composite? To me, it's not a
>composite because it's just one material, glued together in distinct
>layers, not in a matrix like fiberglass and epoxy.
>

One of the most common *Composite* examples is the cardboard box. Same
material, although the center core is shaped to form the required seperation,
then add the glue and we have a very cheap composite structure.
JJ Sinclair

[Chris OCallaghan]

My "suspicion" is that quality control broke down at the Chechia
factory. The quesiton on my mind is, "For how long and to what
degree?" Two gliders from the same factory breaking up in flight in a
single season deserves an explantion from the factory. Since we bet
our lives on these products, that's the least Schempp-Hirth can do.
Even a "We're looking into it" would be appreciated.

"CH" > wrote in message >...
> it looks a bit suspicious that the latest incidents
> concerned gliders out of Schemp Hirth's Chechia
> licence fabrication only.
> CH
>
> ----- Original Message -----
> From: "Chris OCallaghan" >
> Newsgroups: rec.aviation.soaring
> Sent: Wednesday, September 10, 2003 12:29 AM
> Subject: Re: Discus CS grounded in France
>
>
> > Per the French Airworthiness Directive, "separation of the wing during
> > normal operating conditions, possibly the result of a manufacturing
> > defect."

[Jim Culp]

Chris OCallahan stated

'...quality control broke down at the Chechnia factory.
The question is 'For how long and to what degree?'
Two gliders from the same factory breaking up in flight
in a single season quality control broke down at the
Chechia factory. The quesiton on my mind is,
'For how long and to what degree?'

Two gliders from the same factory breaking up in flight
in a single season deserves a factory explanation.
'

------------------------------------------------------------------
-----

Dear Chris,

Maybe the WingGlueMan needs reassignment to
clean shop or answer telefunken;

or

a Beer On The Job rule of not more than 2 grossestein
biers every hour needs some clearminded consideration.




Dancing on clouds,

Keep it up!

Jim Culp USA
GatorCity Florida
Std Libelle H201b (still flyin)

[JJ Sinclair]

Got this second hand info. The scenario goes something like this >>>>>>>>>>

Workers A, B & C don't spread enough glue (cabacil) onto the wing just before
the mating process.

Inspector D, didn't feel it was necessary to have a look, saying, "you guys
have been doing this long enough to know what your doing"

Pilot E, has a rude awakening. He may have just completed a loop when things
started shedding from his sailplane.
JJ Sinclair

[Vorsanger1]

In the recent post, there is a reference to a "Chechnia factory". For
clarity's sake, and nothing else, I think the writer meant the Czech Republic.
Correct me if I am wrong, I have been know to goof before.

Cheers, Charles

[Deputy Dog]

Charles:

I believe that most of the CS's were built by Orlican in Chocen, CZ.
Some of the later ones were built by Schempp-Hirth, Vyr.Let.S.R.

-Deputy Dog


(Vorsanger1) wrote in message >...
> In the recent post, there is a reference to a "Chechnia factory". For
> clarity's sake, and nothing else, I think the writer meant the Czech Republic.
> Correct me if I am wrong, I have been know to goof before.
>
> Cheers, Charles

[Steve B]

There is a company using the Discus BM Wing for a very new design
called the Carat (Motor Glider). It is manufactured by a company in
Slovania called AMS Technoflug and uses a front enging with forward
folding propeller. I assume that they are manufacturing the (Discus
BM) wing design in Slovania. I understand that they are known for very
high quality work... they build many of the DG Gliders.





(Deputy Dog) wrote in message >...
> Charles:
>
> I believe that most of the CS's were built by Orlican in Chocen, CZ.
> Some of the later ones were built by Schempp-Hirth, Vyr.Let.S.R.
>
> -Deputy Dog
>
>
> (Vorsanger1) wrote in message >...
> > In the recent post, there is a reference to a "Chechnia factory". For
> > clarity's sake, and nothing else, I think the writer meant the Czech Republic.
> > Correct me if I am wrong, I have been know to goof before.
> >
> > Cheers, Charles

[JJ Sinclair]

Now I am confused, Eric wrote>>>>>>>>>>>>>>>>>>>>>>>>>>>
>In composite construction, there is no "glue": the resin permeates the
>other material (glass, carbon, Kevlar, etc), and the material
>properties depend on this. There are layers of the fiber, but they
>aren't glued together like the wood layers in plywood.

How is the fiberglass layer bonded to the foam core, if it isn't *glued* with
the resin? I thought you were making the distinction between several layers of
fiberglass cloth, as in a fuselage and fiberglass cloth/ foam core/ fiberglass
cloth, as we find in the wing.
I thought you were saying that plywood wasn't a *composite*, because it didn't
have a core, so therefore couldn't be considered a composite, but now you are
saying that 3 layers of fiberglass is a composite, but 3 layers of wood isn't.

Some of the plywood we use in our sailplanes is made up of mahogany / poplar
core/ mahogany. Sounds like glass /foam core/ glass, with a change in
materials, doesn't it?


JJ Sinclair

[Chris OCallaghan]

Nope, my goof. Finger flutter.

[Marc Till]

Schempp-Hirth, Vyr.Let (Vyroba Letadel means Airplane factory) is the
new name of Orlican

Cheers

Marc

Deputy Dog a écrit:
> Charles:
>
> I believe that most of the CS's were built by Orlican in Chocen, CZ.
> Some of the later ones were built by Schempp-Hirth, Vyr.Let.S.R.
>
> -Deputy Dog
>
>
> (Vorsanger1) wrote in message >...
>
>>In the recent post, there is a reference to a "Chechnia factory". For
>>clarity's sake, and nothing else, I think the writer meant the Czech Republic.
>>Correct me if I am wrong, I have been know to goof before.
>>
>>Cheers, Charles
>

[Mike Borgelt]

On Sat, 13 Sep 2003 01:28:42 +1000, Graeme Cant
> wrote:

>Eric Greenwell wrote:
>> ...We all agree that fiberglass, carbon, Kevlar, etc. cloth
>> with epoxy make a composite material, but plywood? I don't think it
>> is,...
>
>All natural timber is a composite, even by Eric's definition. It's fine
>structure is a composite of fibres and glue, just like GRP.

Cellulose fobres in lignin isn't it?

Mike Borgelt

[Roger Felton]

"The next time someone sneers at a wooden sailplane, remind them that it is
made of a unidirectional reinforced laminated composite material consisting
of micro-tubular fibres embedded in a long chain polymer matrix and having a
near infinite fatigue life."
-Unknown-

RF

Mike Borgelt wrote:

> On Sat, 13 Sep 2003 01:28:42 +1000, Graeme Cant
> > wrote:
>
> >Eric Greenwell wrote:
> >> ...We all agree that fiberglass, carbon, Kevlar, etc. cloth
> >> with epoxy make a composite material, but plywood? I don't think it
> >> is,...
> >
> >All natural timber is a composite, even by Eric's definition. It's fine
> >structure is a composite of fibres and glue, just like GRP.
>
> Cellulose fobres in lignin isn't it?
>
> Mike Borgelt

[Shaber CJ]

>"The next time someone sneers at a wooden sailplane, remind them that it is
>made of a unidirectional reinforced laminated composite material consisting
>of micro-tubular fibres embedded in a long chain polymer matrix and having a
>near infinite fatigue life."
> -Unknown-
>

The wooden rotor blades on a Bell 47 helicopter (i.e. MASH) were "on condition"
where as the metal blades are life time limited.

[N5360C]

This is a troubling report. I've read both the French and English
version of the grounding order: the English version is an accurate
translation. No mention of high time or turbulence. One finds
oneself drawn to the conclusion that some sort of construction defect
played a role. Tales of third party reports of insufficient resin are
troubling and certainly deserve a more complete explanation,
recognizing, of course, that liability is still being considered by
lawyers. And recognizing too that there is such a thing as too much
resin in composite aircraft construction: you don't just ladle on as
much epoxy as gravity will hold in place if you are trying to find the
best balance of strength and weight. But if a given factory is
producing parts that fail in flight this certainly calls for more than
hints of workmen drinking too much beer and inspectors abdicating
their responsibility. Let's get serious with this, shall we? Does
anyone have more than suspicions of beer drinking and third party
negligence?

[BPattonsoa]

A classical composite is reinforced concrete. Steel reinforcing along with
concrete makes a composite structure. Concrete has fair compressive strength,
3-5,000 psi is generally used, with tensile strength of around 100-500 psi,
miserable. When reinforcing steel, 40- 60,000 psi is added, and suffucient
bond provided (like joining together two composite structures in a spar/skin
joint), the steel takes the load in tension while the concrete takes the load
in compression. (Steel rods in compression are OK only as short lengths before
they buckle)
This is a simple example: where a single bar of steel is in the bottom of a
simple concrete beam and none is in the top. Loading produces tension in the
bottom of the beam while compression is in the top. Each material then uses
its best property to provide a composite structure superior to each
individually.

Bruce Patton
(A civil engineer to pay for soaring)
96S, aka, JJ, " Tinman"

[Eric Greenwell]

In article >,
says...
> Now I am confused, Eric wrote>>>>>>>>>>>>>>>>>>>>>>>>>>>
> >In composite construction, there is no "glue": the resin permeates the
> >other material (glass, carbon, Kevlar, etc), and the material
> >properties depend on this. There are layers of the fiber, but they
> >aren't glued together like the wood layers in plywood.
>
> How is the fiberglass layer bonded to the foam core, if it isn't *glued* with
> the resin? I thought you were making the distinction between several layers of
> fiberglass cloth, as in a fuselage and fiberglass cloth/ foam core/ fiberglass
> cloth, as we find in the wing.

It's my understanding that "composite" generally means the fiberglass
and epoxy itself. No core is needed to have a composite structure:
just look at the fuselage construction of many fiberglass gliders.
--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly

Eric Greenwell
Richland, WA (USA)

[JJ Sinclair]

As I write this, I am looking at a cross-section of an ASW-22 wing, taken from
a ship that has met with misfortune, It has styrofoam dams at the leading edge,
on both sides of the upper spar cap and at the forward edge of the drag spar.
These styrofoam dams were set just high enough to allow for a 10% excess of
glue (epoxy resin, chopped fibers, micro-balloons) that were trawled in from
the edge of one dam to the edge of the other dam. In this way, the construction
crew was 100% sure that the proper amount of glue had been spread along the
spar cap. When the upper skin was mated, all voids were filled and the excess
10% of resin was forced out each side into the styrofoam dams.
The inside of this wing is a work of art. I would expect nothing less from all
sailplane manufactures.
JJ Sinclair

[Slingsby]

(JJ Sinclair) wrote in message >...
> As I write this, I am looking at a cross-section of an ASW-22 wing, taken from
> a ship that has met with misfortune, It has styrofoam dams at the leading edge,
> on both sides of the upper spar cap and at the forward edge of the drag spar.
> These styrofoam dams were set just high enough to allow for a 10% excess of
> glue (epoxy resin, chopped fibers, micro-balloons) that were trawled in from
> the edge of one dam to the edge of the other dam. In this way, the construction
> crew was 100% sure that the proper amount of glue had been spread along the
> spar cap. When the upper skin was mated, all voids were filled and the excess
> 10% of resin was forced out each side into the styrofoam dams.
> The inside of this wing is a work of art. I would expect nothing less from all
> sailplane manufactures.
> JJ Sinclair

It is interesting that you mention dams on BOTH sides of the upper
spar cap, as the AD for the Duo Discus had an inspection of the rear
side of the upper spar cap only. There must be an assumption that if
epoxy resin oozed out the back it equally oozed out the front side.
How good is that assumption? If it is possible to have voids where
there is no bonding of the cap to the shear web it must also be
possible to have a partial bonding of the upper aft corner of the web
but not the top and front side. How strong would this spar be? Would
it fail after 1000 hours and only in "extreme turbulance"? Why
wouldn't they have checked both sides of the spar?

[Slingsby]

"George William Peter Reinhart" > wrote in message >...
> Yep,
> Makes you wonder doesn't it?
YUP.
> Where are the cut offs for High Time and "severe " turbulence that would
> make it not OK to fly?
How about 1000 hours and/or 5 years.
> Currently flying a well aged Nimbus with over 1000 hours on it.
No problem as long as you don't feel any "bumps" in the air. Or you
could invest in a Ballistic Recovery Chute System.
> Should I be worried about my personal safety because of the airframe hours? YES
> Are there some days I just shouldn't fly because the "turbulence" might be
> "too high"?
YES, DEFINATELY. Don't fly on days when the air is "bumpy". Cool
winter mornings when the air is smooth should offer the safest
"gliding" and don't bank in turns steeper than 45 Degrees. Tell your
tow pilot to take off slowly.
> All advice carefully considered. Even advise which is recklessly given?
> Cheers!
>
>
> Guy Byars > wrote in article
> >...
> >
> >
> > > I heard it was a high time glider in severe turbulence.
> >
> > And that makes it ok?

[Robertmudd1u]

In article >,
(Slingsby) writes:

>the AD for the Duo Discus had an inspection of the rear
>side of the upper spar cap only. There must be an assumption that if
>epoxy resin oozed out the back it equally oozed out the front side.
>How good is that assumption?

I think SH has you inspect the aft face of the spar because the front side has
a foam dam to help keep the bonding paste from squeezing out. So if there is a
void at the aft side then the void may or may not go through to the front side.
If there is no void it highly likely that there is enough bonding paste all
across the bonding area.

Now I if you don't like the word "likely" when applied to this particular
process then you should not fly any composite glider because such assumptions,
based on tests and real world experience, are used through the construction
process. 100% inspection of every bonded joint is impossible given the
constraints of manufacturing of gliders as it is done now. Perhaps these
incidents will cause the LBA and manufactures to re-think the inspection
standards. And likely raise the price of an already costly toy.

Robert Mudd

[Slingsby]

> Now I if you don't like the word "likely" when applied to this particular
> process then you should not fly any composite glider because such assumptions,
> based on tests and real world experience, are used through the construction
> process. 100% inspection of every bonded joint is impossible given the
> constraints of manufacturing of gliders as it is done now. Perhaps these
> incidents will cause the LBA and manufactures to re-think the inspection
> standards. And likely raise the price of an already costly toy.
> Robert Mudd
************************************************** *********************************
W. Edwards Deming the father of statistical process control showed
that a 100% inspection system will regularly miss 20% of the defects.
The goal of manufacturing and design should be to develop a process
which minimizes the likelyhood of defects, especially catastrophic
defects.
The DG website has a very detailed explanation of how a wing is
constructed and I assume the technique is similar for all German
designed gliders. Spar CAPS are formed with carbon fibre rovings and
are inspected in minute detail for voids and any cap which fails
inspection is immediately cut in half to preclude its inadvertant use.
As the upper and lower wing skins are moulded, the spar caps are
glued in place so that they are well bonded to the skin. So far so
good, the top and bottom of an I-beam shaped spar are well built and
in place. Next the shear web, which is also well built and inspected
is glued into the bottom part of the spar cap. Gravity holds the glue
in place and the surface is well lighted and clean so the craftsmen
and inspectors can see what is happening. The wing spar is now an
upside down T shape. Later on in the process the top surface of the
wing is glued to the bottom half forming both a wing and a complete
spar. It can be SEEN that the exterior surfaces of the wing are well
mated because epoxy oozes out of the joints. It can only be ASSUMED
that the upper spar cap is well bonded to the shear web because the
glue joints cannot be seen. Assuming you have a good spar because of
German craftmanship works because German craftsmen are quite good, but
it is not a well designed manufacturing process. Building a complete
spar outside of the wing and then bonding it to the upper and lower
surfaces strikes me as a process much less likely to lead to a
catastrophic failure. In the case of the Duo Discus and probably the
Discus CS, failure of the spar is more of a process defect than an
inspection defect.
The price of these costly toys may indeed go up but something bad has
just happened to the value of Shemp Hirth products.

[Dave Nadler \YO\]

"I assume the technique is similar for all German designed gliders."

Very bad assumption. Not even the same for all products from each mfg.

[Slingsby]

"Dave Nadler \"YO\"" > wrote in message >...
> "I assume the technique is similar for all German designed gliders."
>
> Very bad assumption. Not even the same for all products from each mfg.
Could you please explain some of the different spar construction
methods used by the different German manufacturers? Which ones use a
spar which is constructed outside of the wing assembly process?

[Andrew Warbrick]

At 14:12 19 September 2003, Nick Hill wrote:
>John Galloway wrote:
>> At 22:48 18 September 2003, Slingsby wrote:
>>
>> >The price of these costly toys may indeed go up but
>>
>>>something bad has
>>>just happened to the value of Shemp Hirth products.
>>
>
>snip...
>
>>
>> Firstly, only spars built at the Czech factory were
>> built incorrectly using an simple error in the technique
>> which has been identified and we can be pretty sure
>> it has been eliminated.
>>
>> Secondly, therefore, the bulk of the German built
>>SH
>> fleet are unnaffected and I think the glider buying
>> public are informed enough to be able to figure that
>> out.
>>
>> Thirdly, all the SH gliders that could possible be
>> affected (i.e. Discus and Duo with Czech wings) have
>> been or will be inspected and, if necessary, repaired
>> and brought up to full airworthiness.
>>
>
>Maybe a better statement is the reputatation of Schempp
>Hirth products
>and procedures. It is fine to say the Czech built ones
>are at fault but
>you buy them from Schempp Hirth who therefore carry
>the responsibility
>for the production and quality control.
>
>Nick Hill
>
>
Better than this.

When our club ordered its Discus B they specifically
asked for a German built glider and payed more for
the privilege, they were told that 'some components
would come from the Czech republic in accordance with
normal manufacturing' it turns out that 'some components'
are the sodding wings, the glider was grounded (during
a competition!) and the club is still losing revenue.

[Bob Kuykendall]

Earlier, Slingsby wrote:

> I assume the technique is similar
> for all German designed gliders."

And Dave Nadler replied:

> Very bad assumption...

And Slingsby responded:

> Could you please explain some of
> the different spar construction
> methods used by the different
> German manufacturers? Which ones
> use a spar which is constructed
> outside of the wing assembly process?

To which I say:

Slingsby, I think you kind of slipped a groove back there. You started
off by talking about "German designed gliders," but after Dave
responded you changed the topic to German manufactured gliders.

Design and manufacture are two different things.

A survey of the Akaflieg Web pages might show a couple of examples of
German designs with the characteristics you are talking about. What
then?

Bob K.

[Marc Ramsey]

"John Galloway" > wrote...
> Thirdly, all the SH gliders that could possible be
> affected (i.e. Discus and Duo with Czech wings) have
> been or will be inspected and, if necessary, repaired
> and brought up to full airworthiness.

I believe some recent Ventus 2 wings were also constructed in the Czech factory,
I would hope they have plans to inspect those, as well.

I am, by the way, very much impressed with the way Schemmp-Hirth notified and
provided support to those of us with Duos, whether or not the glider was still
in warranty. It was a class act, and I wouldn't hesitate to buy another SH
glider.

Marc

[John Galloway]

At 17:42 19 September 2003, Marc Ramsey wrote:
>
>I believe some recent Ventus 2 wings were also constructed
>in the Czech factory,
>I would hope they have plans to inspect those, as well.
>
Marc,

Agreed.

However, according to what we were told the construction
technique error on the Duos, at least, was so simple
and specific that they might be able to positively
identify some Czech spars that are not under suspicion.


IMHO it would be in Schempp-Hirth's best interests
to publish a full account of the production problem,
the rationale behind the inspection and repair procedure,
and the actions taken to ensure future quality standards.

John Galloway

[Slingsby]

John Galloway > wrote in message >...
> At 22:48 18 September 2003, Slingsby wrote:
>
> >The price of these costly toys may indeed go up but
> >something bad has
> >just happened to the value of Shemp Hirth products.
>
>
> This is unlikely to happen as glider buyers and sellers
> are not fools. Buyers are unlikey to avoid gliders
> that are perfectly airworthy and sellers are unlikely
> to give them away. If they aren'r aware already bofore
> long they will be that:

The opinion that "Safety doesn't sell" which is discussed on the DG
website might provide an argument to your statement that buyers and
sellers are not fools. The concept of a Czech manufactured Duo Discus
or Discus being "perfectly airworthy" is in the eye of the beholder.
As I ponder whether or not to buy a used Discus, which is the better
log book entry, "AD complied with and no voids in the wing spars were
found," or "AD complied with and a sufficient amount glue was squirted
into the wing spar so that they can never fall apart. Wings are now
perfectly airworthy."


> Firstly, only spars built at the Czech factory were
> built incorrectly using an simple error in the technique
> which has been identified and we can be pretty sure
> it has been eliminated.

Right, a "simple error in the technique" lead to wings breaking off in
normal flight. We can be "pretty sure" it has been eliminated because
we sent our best German craftsmen to the Czech factory to, once again,
show them how to spread glue on a spar cap. The problem is eliminated,
Murphys Law will not rear its ugly head around here again.

> Secondly, therefore, the bulk of the German built SH
> fleet are unnaffected and I think the glider buying
> public are informed enough to be able to figure that
> out.
The glider buying public will also be informed whenever a Shemp-Hirth
glider breaks apart in flight.

> Thirdly, all the SH gliders that could possible be
> affected (i.e. Discus and Duo with Czech wings) have
> been or will be inspected and, if necessary, repaired
> and brought up to full airworthiness.

Right, and the German built gliders couldn't possibly be affected because
none of them have broken apart, yet. Until then, they are fully airworthy.

> As an inspected Duo owner I have made it my business
> to be certain in my own mind that an inspected or repaired
> glider will be at full design spar strength - for example
> that there have been no post manufacturing new delaminations
> in the Czech wings, that wings that pass the visual
> inspection actually are strong.

> I have no particular sentimental attachment to Schemmp-Hirth
> and no business relationship with them. Like most
> affected owners I was pretty upset but now I know the
> facts I feel no need to be concerned about the strength
> or value of our Duo. I have also just ordered a new
> Schempp-Hirth glider.

> Lastly, there is no reason to think that the cost of
> new gliders will go up. There is nothing wrong in
> principle with the way that they are built - as long
> as they are built as intended.
>
> John Galloway

They weren't built as intended, and the blind method of assembling
the spar as the wing is being assembled is wrong in principle. You
should be pretty upset, THEY DIDN'T GLUE THE SPAR TOGETHER. Not just
one, THEY DIDN'T GLUE THE SPAR TOGETHER ON A WHOLE BUNCH OF WINGS. Oops!!!
But hey, "now I know the facts I feel no need to be concerned about the
strength or value of our Duo. I have also just ordered a new Shemp-Hirth
glider" Nice sales pitch, how much are you asking for your Duo?

[John Galloway]

At 22:06 19 September 2003, Slingsby wrote:
>John Galloway wrote in message news:...
>> At 22:48 18 September 2003, Slingsby wrote:
>>
>> >The price of these costly toys may indeed go up but
>> >something bad has
>> >just happened to the value of Shemp Hirth products.
>>
>>
>> This is unlikely to happen as glider buyers and sellers
>> are not fools. Buyers are unlikey to avoid gliders
>> that are perfectly airworthy and sellers are unlikely
>> to give them away. If they aren'r aware already bofore
>> long they will be that:
>
>The opinion that 'Safety doesn't sell' which is discussed
>on the DG
>website might provide an argument to your statement
>that buyers and
>sellers are not fools. The concept of a Czech manufactured
>Duo Discus
>or Discus being 'perfectly airworthy' is in the eye
>of the beholder.
>As I ponder whether or not to buy a used Discus, which
>is the better
>log book entry, 'AD complied with and no voids in the
>wing spars were
>found,' or 'AD complied with and a sufficient amount
>glue was squirted
>into the wing spar so that they can never fall apart.
> Wings are now
>perfectly airworthy.'
>
That's not the full repair . I agree that I would
prefer one that didn't need a repair - but mainly because
it didn't have holes cut in the wing skins to do the
work. I was also very pleased that ours were OK.


The airworthiness of passed or repaired wings is not
in the eye of the beholder - unless you have some technical
information to show otherwise - or perhaps you think
the factory, the LBA and the local airworthiness organisations
are incompetent or part of a conspiracy?


>> Firstly, only spars built at the Czech factory were
>> built incorrectly using an simple error in the technique
>> which has been identified and we can be pretty sure
>> it has been eliminated.
>
>Right, a 'simple error in the technique' lead to wings
>breaking off in
>normal flight. We can be 'pretty sure' it has been
>eliminated because
>we sent our best German craftsmen to the Czech factory
>to, once again,
>show them how to spread glue on a spar cap. The problem
>is eliminated,
>Murphys Law will not rear its ugly head around here
>again.

I am not sure what point is being made in the above.
As far as I am aware Murphy's Law is spread evenly
throughout human activity. I thought that's what it
was about. And are you suggesting that retraining
cannot possibly correct a production error?

>> Secondly, therefore, the bulk of the German built
>>SH
>> fleet are unnaffected and I think the glider buying
>> public are informed enough to be able to figure that
>> out.
>The glider buying public will also be informed whenever
>a Shemp-Hirth
>glider breaks apart in flight.


How could it be otherwise?



>> Thirdly, all the SH gliders that could possible be
>> affected (i.e. Discus and Duo with Czech wings) have
>> been or will be inspected and, if necessary, repaired
>> and brought up to full airworthiness.
>
>Right, and the German built gliders couldn't possibly
>be affected because
>none of them have broken apart, yet. Until then, they
>are fully airworthy.

Are you accusing Schemmp-Hirth of lying when they say
that only Czech wings were built by the faulty technique?
Or are you suggesting that properly built spars are
not airworthy? If so back it up - and remember that
this is a public forum.

>
>> As an inspected Duo owner I have made it my business
>> to be certain in my own mind that an inspected or
>>repaired
>> glider will be at full design spar strength - for
>>example
>> that there have been no post manufacturing new delaminations
>> in the Czech wings, that wings that pass the visual
>> inspection actually are strong.
>
>> I have no particular sentimental attachment to Schemmp-Hirth
>> and no business relationship with them. Like most
>> affected owners I was pretty upset but now I know
>>the
>> facts I feel no need to be concerned about the strength
>> or value of our Duo. I have also just ordered a new
>> Schempp-Hirth glider.
>
>> Lastly, there is no reason to think that the cost
>>of
>> new gliders will go up. There is nothing wrong in
>> principle with the way that they are built - as long
>> as they are built as intended.
>>
>> John Galloway
>
>They weren't built as intended, and the blind method
>of assembling
>the spar as the wing is being assembled is wrong in
>principle. You
>should be pretty upset, THEY DIDN'T GLUE THE SPAR TOGETHER.
> Not just
>one, THEY DIDN'T GLUE THE SPAR TOGETHER ON A WHOLE
>BUNCH OF WINGS. Oops!!!

This is simply stating what we already know. That
is the starting point of the whole problem. Things
have moved on from there and the wings are being checked
and repaired if needed. It is self evident that this
is the biggest manufacturing error in modern gliding
history but it is being sorted - not without a lot
of inconvenience and irritation for the owners but
it is happening.

As regards the 'blind' construction method for the
spars - if you have knowledge to suggest that passed
or repaired Czech wings, or German built wings, or
any SH wings built from now on are not airworthy please
state it. This is, as you are shouting out, a pretty
serious matter and would benefit from information rather
than assertion or insinuation.

'now I know the facts I feel no need to be concerned
about the
>strength or value of our Duo. I have also just ordered
>a new Shemp-Hirth
>glider' Nice sales pitch, how much are you asking
>for your Duo?

It would not have been proper for me not to have declared
my relevant interests in this matter and why it has
been important to me to be sure of the situation.
Weather permitting, tomorrow (like all the other inspected
owners) I will be betting my life that our Duo spar
is sound and then, in the future, I will also be betting
a bigger chunk of the value of my house than I like
to think about that the next glider will also be sound.


Our confidence in the structural integrity of a composite
aircraft comes from our confidence in the integrity
of of the constructor. That isn't a complete defence
against a mistake being made and when it does we then
have to judge whether the constructor has shown the
integrity to learn from the problem, make good the
consequences of it, make sure it can't happen again,
and then extend the audit process to prevent other
types of error occuring in the future.

Your feelings about this problem are much milder than
mine were a few weeks ago. As far as I was concerned
I had to get all the facts I could and then judge whether
(as said before) I was being told the truth or whether
several agencies were being simultaneously incompetent
and/or dishonest because that would be the only other
logical conclusion.


John Galloway

[Slingsby]

> That's not the full repair . I agree that I would
> prefer one that didn't need a repair - but mainly because
> it didn't have holes cut in the wing skins to do the
> work. I was also very pleased that ours were OK.

I might prefer one which did need a repair as I suspect that finding
a void, poking a wire into it to find a much larger hidden air pocket
will trigger a much more detailed inspection of the spar cap than just
using a video. That would lead to a very thorough filling of the
voids.
Limiting the inspection to a video of the rear of the upper spar cap
won't find hidden air pockets. This may all be changing with Discus
CS.
I also wonder if an ultrasonic inspection could be done which could
map
the spar cap to shear web interface.

> The airworthiness of passed or repaired wings is not
> in the eye of the beholder - unless you have some technical
> information to show otherwise - or perhaps you think
> the factory, the LBA and the local airworthiness organisations
> are incompetent or part of a conspiracy?
>
The perceived airworthiness of a wing is very much in the eye of
the beholder. Whether a glider flys regularly or sits in a box for
several seasons because the owner can't sell it and is too nervous
to fly it is based more on perception of safety than actual safety.
Some pilots stop flying after a bout with rough air. I'm not charging
incompetence or conspiracy but in an earlier posting I mentioned
Deming
and my belief that there is a process problem which is more serious
than just the Czech factory and Schemp-Hirth. The process problem has
more to do with how the wing and spar are designed and assembled and
whether the construction method leads to tightly consistant results
every
single time or variability in results. Variability leads to failure.
Not
knowing if you always get the right amount of glue on the spar joint
is
a process which is out of control. German craftsmen may decrease the
variability and Czech employees may increase the variability but it is
the process which needs to be changed.


> >> Firstly, only spars built at the Czech factory were
> >> built incorrectly using an simple error in the technique
> >> which has been identified and we can be pretty sure
> >> it has been eliminated.
> >
> >Right, a 'simple error in the technique' lead to wingsbreaking
off in normal flight. We can be 'pretty sure' it has been
> >eliminated because we sent our best German craftsmen to the Czech factory
> >to, once again, show them how to spread glue on a spar cap. The problem
> >is eliminated, Murphys Law will not rear its ugly head around here
> >again.
>
> I am not sure what point is being made in the above.
> As far as I am aware Murphy's Law is spread evenly
> throughout human activity. I thought that's what it
> was about. And are you suggesting that retraining
> cannot possibly correct a production error?

Process again. Murphy's Law should serve as a constant reminder to
look
for areas where it can occur and minimize its ability to occur. It's
not
entirely random. If applying adhesive to 30 feet of a spar cap and
web is part and parcel of a process which simultaneously applies glue
to several hundred feet of rib and wing edges and if it is possible to
miss a few spots every 20 or so wings then there will always be spar
caps which are not completely glued together. Retraining might
minimize the occurence but it probably won't eliminate it.