Blanik Mandatory Bulletin No. L13/116a ?

On Thursday, March 21, 2013 12:20:13 PM UTC-4, Evan Ludeman wrote:
The way I read it, this is about determining if the correct material (i.e. alloy) was used.

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

I haven't seen the document, but Evan is correct about eddy current's ability to separate materials based on their conductivity. It can also be used to find very small cracks, and is much better in the field in finding cracks than using hand applied and removed dye penetrant. Eddy current's big drawback is liftoff, eg, you get a large signal when the probe either comes off the material a little bit or if the probe tilts. Using an instrument that displays the signals on the impedance plane helps mitigate liftoff and allows you to discern material changes from cracks, and a probe holder helps control liftoff.

-John, Q3

On Mar 21, 9:20*am, Evan Ludeman wrote:

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.

I imagine a future bulletin from LET. One that can be summarized as
follows:

"We determined that in several Blanik gliders wrong alloy was used to
make the spar cap. Those gliders are subject to premature cracking due
to fatigue.
All gliders with spars made from the correct material are safe and can
be returned to service. Here's how to determine what you have..."

One can dream, right?

Bart

Is there someone in the US that has a connection to the FAA that can bring
this letter to their attention so we can get some official determination on
it? If not I will start making calls. DOug

Eddy Current Testing is only used to find cracks. It has nothing to do
with determining the alloy.

FYI - I worked at one top Non Destructive Testing companies in the North
American nuclear industry. We used Eddy Current all the time to find
cracks.

I agree with the comments the factory is trying to gather more data on
cracks. If LET can go back to EASA with data on a large volume of gliders
maybe they can argue the gliders can fly.

On the converse, if a large volume of owners don't provide the data to LET,
they can argue there is not enough interest from the owners to solve the
problem and do nothing to solve the issue.

Andrew




At 22:52 21 March 2013, Bart wrote:
On Mar 21, 9:20=A0am, Evan Ludeman wrote:

I don't think so. =A0I think it's about bulk electrical conductivity
beca=
use that's what it says in the document ("% IACS", or in other words,
condu=
ctivity relative to an annealed copper standard). =A0And that tells me
they=
suspect that an unauthorized material substitution may have occurred in
so=
me cases.

I imagine a future bulletin from LET. One that can be summarized as
follows:

"We determined that in several Blanik gliders wrong alloy was used to
make the spar cap. Those gliders are subject to premature cracking due
to fatigue.
All gliders with spars made from the correct material are safe and can
be returned to service. Here's how to determine what you have..."

One can dream, right?

Bart

On Friday, March 22, 2013 11:22:58 AM UTC-6, Doug Mueller wrote:
Is there someone in the US that has a connection to the FAA that can bring

this letter to their attention so we can get some official determination on

it? If not I will start making calls. DOug

Replied to you off group. If your SSA contact info is correct, that is.

Frank Whiteley

On Friday, March 22, 2013 4:26:33 PM UTC-4, Andrew Corrigan wrote:

FYI - I worked at one top Non Destructive Testing companies in the North

American nuclear industry. We used Eddy Current all the time to find

cracks.

Then surely you can see how this chart might be useful to an investigator who had evidence (say, metallurgical analysis of failed wing spar) of material substitution. Aluminum alloys and even different tempers of same alloy vary in conductivity quite a lot.

http://www.ndt-ed.org/GeneralResourc...ctivity_Al.pdf

regards,
T8

From what I hear from the Beechcraft T-34 guys, who also have wing spar issues, it is very difficult to find people who can do this testing in the field and it is expensive. I would think if LET really thinks this is necessary they would provide a little more info as to what they think this will accomplish.

-karl

On Wednesday, March 20, 2013 10:58:17 AM UTC-7, 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

On Thursday, March 21, 2013 12:20:13 PM UTC-4, Evan Ludeman wrote:
...that tells me they suspect that an unauthorized material substitution may have occurred in some cases.


On Thursday, March 21, 2013 6:52:07 PM UTC-4, Bart wrote:
...(ed. wishful thinking) All gliders with spars made from the correct
material are safe and can be returned to service...

On Saturday, March 23, 2013 9:58:54 AM UTC-4, Karl Kunz wrote:
...it is very difficult to find people who can do this testing in the field and it is expensive.

If all three of these statements are correct, then it would be worthwhile to outfit a certified technician in a van with the right equipment, go on a road trip, and test a large number of grounded Blaniks in a short time. If they were all tested by the same technician, with the same equipment, the dataset would be more convincing, especially if it revealed a serial number range that used a crack prone alloy.

Payback would be huge if most of the L-13s were returned to service.
Hard to fund/organize? Yep. Worth it? Yep.

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

I've been after them for over two years to OK an xray inspection. Nobody seems interested. No money in for anybody. We've XRAYED and Mag Fluxed (one was bent, came out of a wreak) twelve of these fittings and nobody cares. None were cracked.
My plan was to do xray inspection every three years or less if they want. Change flight manual to limit Vne to 100kts, No ground launches,NO aerobatics, Only those maneuvers necessary for a commercial license. We had it all set up but no one cared.
The NDT guy would go to your field and do all the L 13s you could bring. Oh, I forgot, The XRAY can be done without taking anything apart. How's that for apples? I know it works,We did it. We did it at many different angles and exposures and it works great BUT nobody listened or cared. Gino DiNucci CFI,II,G and A&P IA

On Saturday, March 23, 2013 10:33:14 AM UTC-6, Low-N-Slow wrote:
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



I've been after them for over two years to OK an xray inspection. Nobody seems interested. No money in for anybody. We've XRAYED and Mag Fluxed (one was bent, came out of a wreak) twelve of these fittings and nobody cares. None were cracked.

My plan was to do xray inspection every three years or less if they want. Change flight manual to limit Vne to 100kts, No ground launches,NO aerobatics, Only those maneuvers necessary for a commercial license. We had it all set up but no one cared.

The NDT guy would go to your field and do all the L 13s you could bring. Oh, I forgot, The XRAY can be done without taking anything apart. How's that for apples? I know it works,We did it. We did it at many different angles and exposures and it works great BUT nobody listened or cared. Gino DiNucci CFI,II,G and A&P IA

Let's review. The FAA certainly did consider x-raying, but unless it comes from EASA, they probably won't budge on that.

http://www.ssa.org/files/member/Clar... %20091410.pdf

http://www.ssa.org/files/member/opin...ers_092010.pdf

http://www.ssa.org/files/member/Blan...Jan%202011.doc

http://www.ssa.org/myhome.asp?mbr=67...iv e=4/1/2011

http://www.ssa.org/myhome.asp?mbr=8671991229&id=2753

http://www.ssa.org/MyHome.asp?mbr=6789819598&show=-1'&id=3030

Gino,

At the time, I located about 11 wings that could have been x-rayed, then disassembled to validate the process. Unfortunately, logs for said wings were not available, which would not have helped the process. In any event, the FAA wouldn't consider an AMOC as an L-13 owner with a CNC shop and DER in Arizona were exploring.

However, as the above links will disclose, the FAA is not going to move without EASA addressing certain issues. However, EASA did move on L-13A's (those with the modified root to L-23 design), but there is no way to tell from the US registry if there are any in the US unless the owners speak up. There was discussion on RAS that some update was forthcoming, but I haven't seen it and the SSA Governmental Liaison airworthiness representative was not able to attend the recent SSA BOD meeting in Houston.

On another topic, the SSA has queried the FAA after reports from the UK emerged about an SB for a life extension program of the IS28-B2 Lark as we probably have 25 or so currently grounded.

I don't have any sage advice regarding the L-13's and whether owners should pickle them, turn them into sims, or put them out as display signs or wind roses. I think it was unfortunate that a more prudent decision, like allowing those with less than 1800 hours to keep flying normally, or under restricted conditions, wasn't taken by EASA, but that's just my personal opinion. Likewise, the reluctance to consider an AMOC is disappointing.

Frank Whiteley