Wow! Ooops, take #3

Yikes.
http://ad.easa.europa.eu/ad/2015-0052-E

On Thursday, April 2, 2015 at 4:44:59 PM UTC-4, Dave Nadler wrote:
Yikes.
http://ad.easa.europa.eu/ad/2015-0052-E

Wow, there are many more pure gliders now...

On Thursday, April 2, 2015 at 4:16:21 PM UTC-5, Andrzej Kobus wrote:
On Thursday, April 2, 2015 at 4:44:59 PM UTC-4, Dave Nadler wrote:
Yikes.
http://ad.easa.europa.eu/ad/2015-0052-E

Wow, there are many more pure gliders now...

Hmm. Says it only applies if you have Solo 2350 c and a non foldable propeller. But in the "reason" section, it implies that all Solo 2350 C engine operation is prohibited. Don't know enough on the specific variants of the Solo 2350 to know how many this really impacts.

Also interesting is that you must inspect within 30 days and report your findings. Even if there is no issue to report, it does not remove the restriction from using the engine.

Bad news for all that are affected.

It will only be a matter of time before the U.S. FAA issues an AD based on the AESA AD that will impact gliders in the US.
US owners should heed the cautions and not operate the SOLO engine.
Interesting that the AD specifically identified the previous SOLO service bulletin as not acceptable.

BillT

Looking at the Solo website http://aircraft.solo-online.com/index.php it looks like the c model is very different in that it shows a belt drive while the straight 2350 shows a direct drive. It appears that the AD is only for the C model.

DVM

God doesn't like motors on sailplanes.......

On Thursday, April 2, 2015 at 4:44:59 PM UTC-4, Dave Nadler wrote:
Yikes.
http://ad.easa.europa.eu/ad/2015-0052-E

The product information website for Solo engines shows that two models of gliders are affected: Ventus CM and the DG1000T. Other gliders with solo motors have differing model numbers.

On Thursday, April 2, 2015 at 4:44:59 PM UTC-4, Dave Nadler wrote:
Yikes.
http://ad.easa.europa.eu/ad/2015-0052-E

Sounds along the lines of this.....

http://www.bugatti100p.com/web_docum...lvibration.pdf

Sorta long read (the link), but curious to see results from the new AD.

On Thursday, April 2, 2015 at 2:44:59 PM UTC-6, Dave Nadler wrote:
Yikes.
http://ad.easa.europa.eu/ad/2015-0052-E

Based on Mr Nadler's description, failure more or less inevitable.
Too small a radius will reduce the part's fatigue limit by somewhere between one third and one half roughly speaking. A 90 degree non-radius would result in a more or less infinite reduction in the fatigue limit (which is the stress on a part below which it should have an infinite fatigue life; in the real world all sorts of things reduce this limit, as we are seeing).
Rough machining can be even more insidious. Each piece of rough machining that you can see by eye is more or less the same as an already existing early fatigue crack. Its root radius at a microscopic level is effectively infinite with a corresponding reduction in the fatigue limit. Very bad news especially when it happens at a designed in place of inherently high stress.
All they had to do was to add some hard chromium plate on any wear surface that ran around the radius and failure would have been even earlier.
Pretty basic stuff. For it to have been repeated, as seems to have happened after a known problem, amounts to extreme carelessness.

On Friday, April 3, 2015 at 5:25:34 PM UTC-4, howard banks wrote:
On Thursday, April 2, 2015 at 2:44:59 PM UTC-6, Dave Nadler wrote:
Yikes.
http://ad.easa.europa.eu/ad/2015-0052-E

Based on Mr Nadler's description, failure more or less inevitable.
Too small a radius will reduce the part's fatigue limit by somewhere
between one third and one half roughly speaking. A 90 degree non-radius
would result in a more or less infinite reduction in the fatigue limit
(which is the stress on a part below which it should have an infinite
fatigue life; in the real world all sorts of things reduce this limit,
as we are seeing).
Rough machining can be even more insidious. Each piece of rough machining
that you can see by eye is more or less the same as an already existing
early fatigue crack. Its root radius at a microscopic level is effectively
infinite with a corresponding reduction in the fatigue limit.
Very bad news especially when it happens at a designed in place of
inherently high stress.
All they had to do was to add some hard chromium plate on any wear
surface that ran around the radius and failure would have been even
earlier.
Pretty basic stuff. For it to have been repeated, as seems to have
happened after a known problem, amounts to extreme carelessness.

To be clear: The failed part I examined in fall 2013 was a "take #2" part.
The part was redesigned for "take #3", "resolving" the 2013 AD.
The new "take #3" part failed, leading to the most recent AD.
I have no idea what the failure of "take #3" looks like...

It is a bit surprising that 3 iterations of this part have failed...

But it is not an easy problem!

Hope that is clear,
Best Regards, Dave