L13 Blanik Mandatory Bulletin

On Jun 25, 3:42*pm, JC wrote:
It would be a coincidence but could this be one of the Red Bull
Blaniks? They have Austrian registration and they get flown pretty
hard.
Is there a news article on the accident?

Regards,

Juan Carlos

http://aviation-safety.net/wikibase/wiki.php?id=74748

Link to an image of the glider in hangar on page. Not a Red Bull
Blanik.

Frank Whiteley

Blanik owners and pilots might want to read this call for help from the home
of the Red Bull Blanix team:
http://www.streckenflug.at/popup.php...hilfe.pdf&xy=J

and this question from the author of the above PDF:

Hello,
Does anyone know Detail Information on Blaník which have been modified to
L-13 Type A1, the so called "Llewellyn Modification"?
Even information on the Aeroclub that does this Modification or contact
data, also the name of the Aeroclub would be very helpful for me !

Happy landings and Best Regards!


Walter

On Jun 25, 11:41*am, nimbus wrote:
Inspection was done on our Blahnik this afternoon....

Our Blahnik has a low number of flight...ie. only 1200 hours with 1750
starts.
No acrobatics flight except a few rare loopings...

Always aerotowed...No winch launches...

Inspection with eyes and bright light showed nothing. We took pictures
wtih a small digital cam equipped with a flash (small Olympus one).

When we uploaded the pictures on the PC, we carefully looked at the
pictures and we saw ...longs thin cracks...
With the eyes it was impossible to detect due to the fact that the
available room for inspection is very limited....

We spoke in the previous post about fatigue....well, I am deeply
convinced that our Blahnik has never been "fatigued"....
The cracks seems to be produced because the rivet from which the
cracks are born, has been installed by a hand process during the
manufacturing. The manual process for installing these rivets is clear
on the picture I took.
I strongly suspect a poorly manual manufacturing process instead of a
fatigue problem.

I am really upset to discover this problem now especially that there
is no repair procedure nor a replacement procedure.

The AD just states that the Blanik is grounded. This is unacceptable

Would you consider posting those pics somewhere?

- Evan Ludeman / T8

Originally Posted by Ernst

After a fatal accident in Austria LET issued a Mandatory Bulletin:
http://www.let.cz/files/bulletines/M...9a_english.pdf

EASA issued an Emergency Airworthiness Directive:
http://www.caa.co.uk/docs/33/easa_ad_2010_0119_E.pdf

Could anyone advise the current situation in USA, Canada and Europe regarding the grounding of L13 Blaniks ?

Have many been put back into service as a result of satisfactory wing spar inspections, or do most remain grounded due to the fact that the required average usage statistics required by LET cannot be met, and with respect seem most unreasonable.

For instance – what two seater training glider (or for that matter any two seater glider) would have an average of 35% dual and 65% solo usage! More likely, greater than 80% dual would be a more realistic figure I would have thought.

On Jul 12, 9:39*pm, Ronald Locke Ronald.Locke.
wrote:
Ernst;732355 Wrote:

After a fatal accident in Austria LET issued a Mandatory Bulletin:
http://www.let.cz/files/bulletines/M...9a_english.pdf

EASA issued an Emergency Airworthiness Directive:
http://www.caa.co.uk/docs/33/easa_ad_2010_0119_E.pdf

Could anyone advise the current situation in USA, Canada and Europe
regarding the grounding of L13 Blaniks ?

Have many been put back into service as a result of satisfactory wing
spar inspections, or do most remain grounded due to the fact that the
required average usage statistics required by LET cannot be met, and
with respect seem most unreasonable.

For instance – what two seater training glider (or for that matter any
two seater glider) would have an average of 35% dual and 65% solo usage!
More likely, greater than 80% dual *would be a more realistic figure I
would have thought.

--
Ronald Locke

I haven't heard that the FAA has issued an airworthiness directive
yet, so no L-13's in the USA should be grounded.

Ours was inspected per the bulletinby 2 IAs (concurrently), deemed
airworthy, and signed off. We're flying it.
It had just been down for an annual when the bulletin was released.

John

"John Scott" wrote in message
.. .
Ours was inspected per the bulletinby 2 IAs (concurrently), deemed
airworthy, and signed off. We're flying it.
It had just been down for an annual when the bulletin was released.

John
Same story for my club, almost.

We pulled the wings and inspected everything and it went fine. Ours is
heading into annual next month, but we didn't want to wait.

Bob McKellar

Aluminum, however, does not have the "knee" in the stress/cycle graph
that takes it effectively parallel with the X axis. With aluminum, the
curve heads inexorably towards the X axis.

I see that for some Al alloys and with unnotched coupons, but most all
aircraft metallic structure are notched because of fastener holes. I
am looking at one notched curve now that goes parallel at 10^7
cycles. No glider is going to see the 60-80000 hr life that large
aircraft have proven by service and test. For example, the rewinged
C-5b has an expected service life of 100,000 hrs, validated by fatigue
test. After the test they cut one panel, notched another, and were
unable to get a failure.

Metal structures have been certified with an infinite
fatigue life.

That is almost always true for aircraft certified under the old CAR 3
regulations which did not address fatigue. It is even true for some
aircraft certified under the more modern Part 23 and JAR22
regulations. Unfortunately, the map is not the territory: Just because
the CAA or whoever certified that it is so doesn't mean it is actually
so.

I was referring to among other things, rotor blades cetified in the
70's, that had fatigue, DADT anaylysis and full scale test tests done
with simulated damage.



There is an EXCELLENT, plain language discussion of the design
considerations and fatigue calculations in the Blanik repair and
overhaul manuals published in the mid 70's.

That sounds like valuable material, I would definitely like to read
it. How can I get a copy of that documentation?

I believe the manuals that came with our blanik are available on the
Blanik America site. I think you will find them of great interest,
esp since the EASA AD now is also a US AD as of this Friday.

aerodyne