Blanik Mandatory Bulletin No. L13/116a ?

Hello, All,
Has anyone else seen the latest mandatory bulletin from LET regarding Blaniks (see below? it requires eddy testing for the grounded L-13's. Could this be an alternative method of compliance to make them airworthy again?
Thanks much,
Dylan


https://5da59a70-a-62cb3a1a-s-sites....attredirects=0

The FAA has not weighted in on this yet. Previous notes indicated that they would like to see a response from the LET factory. Well, now they have one.. Hopeful, L-13's will be flying again soon.

Tim Hanke
Adirondack Soaring


On Wednesday, March 20, 2013 1:58:17 PM UTC-4, macquistan wrote:
Hello, All, Has anyone else seen the latest mandatory bulletin from LET regarding Blaniks (see below? it requires eddy testing for the grounded L-13's. Could this be an alternative method of compliance to make them airworthy again? Thanks much, Dylan https://5da59a70-a-62cb3a1a-s-sites....attredirects=0

Unless I missed it, there is no indication regarding a requirement for recurring inspections. Can't believe this is a one time deal.
Blanik owner

On Wednesday, March 20, 2013 8:53:01 PM UTC-7, Boise Pilot wrote:
Unless I missed it, there is no indication regarding a requirement for recurring inspections. Can't believe this is a one time deal.

Blanik owner

I suspect folks here are running ahead of the ball with overly wishful thinking.

To me this looks just like a one-off AD to collect more data and possibly verify there are not missed cracks amongst the repaired/inspected European gliders, not necessarily a specific suggestion to the FAA for an alternate test... although presumably it might lead to that if the eddy current test cleanly finds problems. My worry would be that it seems hard to really know its not missing starting cracks in areas/surfaces that can't be physically inspected/dye tested? So if this is part of an solution eventually you'd certainly expect it to be a reoccurring inspection. Not sure this AD means anything to anybody until the results from the fleet get looked at. Which might (or might not) even end up with worse bad news for owners in the USA or elsewhere.

Darryl

On Thursday, March 21, 2013 4:27:52 AM UTC-4, Darryl Ramm wrote:
On Wednesday, March 20, 2013 8:53:01 PM UTC-7, Boise Pilot wrote:

Unless I missed it, there is no indication regarding a requirement for recurring inspections. Can't believe this is a one time deal.



Blanik owner



I suspect folks here are running ahead of the ball with overly wishful thinking.



To me this looks just like a one-off AD to collect more data and possibly verify there are not missed cracks amongst the repaired/inspected European gliders, not necessarily a specific suggestion to the FAA for an alternate test... although presumably it might lead to that if the eddy current test cleanly finds problems. My worry would be that it seems hard to really know its not missing starting cracks in areas/surfaces that can't be physically inspected/dye tested? So if this is part of an solution eventually you'd certainly expect it to be a reoccurring inspection. Not sure this AD means anything to anybody until the results from the fleet get looked at. Which might (or might not) even end up with worse bad news for owners in the USA or elsewhere.



Darryl

The way I read it, this is about determining if the correct material (i.e. alloy) was used.

T8

Here is the the LET explanation of the MB. It's of little help.....

Dear Sir,

Mandatory bulletin L13/116a requires performance of additional checks onto L13 gliders (At this moment, only L13A and L13 reinforced are released into operation, of course subject to meeting of respective regulations).
Positive result of these checks automatically does not mean that glider can be released into operation.
It is just one of EASA requirements for future possibility to fly. Next requirements will follow up and you will be informed continually.
Mandatory bulletin L13/112a remains valid in all points.

With best regards,

Bruno Kovarik
Product Support Department
tel: +420 572 817 665, fax: +420 572 817 669, e-mail:
-------------------------------------------------------------------------------------------------------------------------
Aircraft Industries, a.s., Na Záhonech 1177, 686 04 Kunovice, Czech Republic, www.let.cz

On Thursday, March 21, 2013 4:34:22 AM UTC-7, Evan Ludeman wrote:
On Thursday, March 21, 2013 4:27:52 AM UTC-4, Darryl Ramm wrote:

On Wednesday, March 20, 2013 8:53:01 PM UTC-7, Boise Pilot wrote:



Unless I missed it, there is no indication regarding a requirement for recurring inspections. Can't believe this is a one time deal.







Blanik owner







I suspect folks here are running ahead of the ball with overly wishful thinking.







To me this looks just like a one-off AD to collect more data and possibly verify there are not missed cracks amongst the repaired/inspected European gliders, not necessarily a specific suggestion to the FAA for an alternate test... although presumably it might lead to that if the eddy current test cleanly finds problems. My worry would be that it seems hard to really know its not missing starting cracks in areas/surfaces that can't be physically inspected/dye tested? So if this is part of an solution eventually you'd certainly expect it to be a reoccurring inspection. Not sure this AD means anything to anybody until the results from the fleet get looked at. Which might (or might not) even end up with worse bad news for owners in the USA or elsewhere.







Darryl



The way I read it, this is about determining if the correct material (i.e.. alloy) was used.



T8

Its an eddy current test. It will detect cracks. Its not going to look at other materiel properties... aka in the wonderful world of poorly written/translated documents cracks are the properties they are looking for.

The illustration in the instruction seems to point to test points between rivets in the vertical web part of the spar cap where it rivets to the man spar vertical member, but it is not that clearly written and illustrated as to exactly what they mean. Ok, positions between rivets, but exactly on what surface... Surely they really mean on the spar cap proper and not the vertical web? I would kind of hope for much clearer instructions and illustrations if this data returned is going to be meaningful. I'd almost expect/hope regulators to question the quality of these instructions.

Darryl

On Thursday, March 21, 2013 11:26:40 AM UTC-4, Darryl Ramm wrote:
On Thursday, March 21, 2013 4:34:22 AM UTC-7, Evan Ludeman wrote:

On Thursday, March 21, 2013 4:27:52 AM UTC-4, Darryl Ramm wrote:



On Wednesday, March 20, 2013 8:53:01 PM UTC-7, Boise Pilot wrote:







Unless I missed it, there is no indication regarding a requirement for recurring inspections. Can't believe this is a one time deal.















Blanik owner















I suspect folks here are running ahead of the ball with overly wishful thinking.















To me this looks just like a one-off AD to collect more data and possibly verify there are not missed cracks amongst the repaired/inspected European gliders, not necessarily a specific suggestion to the FAA for an alternate test... although presumably it might lead to that if the eddy current test cleanly finds problems. My worry would be that it seems hard to really know its not missing starting cracks in areas/surfaces that can't be physically inspected/dye tested? So if this is part of an solution eventually you'd certainly expect it to be a reoccurring inspection. Not sure this AD means anything to anybody until the results from the fleet get looked at. Which might (or might not) even end up with worse bad news for owners in the USA or elsewhere.















Darryl







The way I read it, this is about determining if the correct material (i..e. alloy) was used.







T8



Its an eddy current test. It will detect cracks. Its not going to look at other materiel properties... aka in the wonderful world of poorly written/translated documents cracks are the properties they are looking for.

I don't think so. I think it's about bulk electrical conductivity because that's what it says in the document ("% IACS", or in other words, conductivity relative to an annealed copper standard). And that tells me they suspect that an unauthorized material substitution may have occurred in some cases.

T8

Evan,

I retread the AD and suspect you are correct. Which also makes of course exactly where in the spar cap is tested not important.

Darryl

On Mar 21, 8:26*am, Darryl Ramm wrote:

Its an eddy current test...

Darryl, I think Evan is right; this test is just conductivity between
two specified points. All it could possibly determine is the
resistance of the material, and cracks would have little effect on
that unless they were so bad that the wing would already have failed
under its own weight. The intent appears to be to collect information
that could provide data about alloy and temper.

The test points specified appear to be on the flange of the spar cap
angle near where it is riveted to the shear web. If I recall
correctly, the Blanik wing spar cap consists of that angle plus a
reinforcing strap riveted to the inner surface of one leg. At the
root, the forged steel attachment fitting is wedged between the angle
and the strap and secured to the two with rivets.

When the skin is later applied, some of those rivets that join the
steel fitting to the aluminum spar cap are drilled through along their
axes, and smaller rivets are driven through them to secure the wing
skin in that area. It is a pretty elegant system, since in theory the
shear strength of the two coaxial rivets is no less than that of a
single solid rivet. In practice, however, it makes for a complicated
assembly with many opportunities for errors and disruptions that can
compromise the structure.

Thanks, Bob K.