New MSB about to be issued

[mhoran]

I'm surprised that Diamond is recommending taking the oil sample from the drain valve. Blackstone says not to take an immediate sample but rather take samples throughout draining of the sump, as the first bit of oil out the drain valve will be older (what has settled at the bottom.) They sell a vacuum pump so you can take periodic samples without having to drain the whole sump: https://www.blackstone-labs.com/products/vacuum-pump/. I guess Diamond's never heard of such a thing.

[pete423]

I listened to most of the call with Diamond today regarding the MSB. Here are a few takeaway I got from it, please correct me if I understood it wrong.

1. Oil sample can only detect oversized piston that is rubbing.
2. The oversized piston pin issue that cause cracked piston currently cannot be detected. (The picture was sobering)
3. The core exchange they currently offer has cylinder that has been reworked to accommodate the slightly larger pistons.
4. They are producing 20 core exchange per week, and they are shipping already.
5. The oversized piston was sourced from the original Mercedes Supplier.
6. The 900 hours was selected due to CURRENT DOCUMENTED CASE of failure at 1200+ hours and that there are currently six DOCUMENTED CASES of engine failure.

On the DA42 forum there is a thread of "piston melted in the cylinder" at 983 hours. That sounds awfully close to what the MSB is covering. If this or other cases becomes a DOCUMENTED CASE, would they have to adjust the artificial 900 hours mark lower?

From what I can understand, all the affected engines are the ones Austro built themselves instead of the ones they purchased from Mercedes. Perfecting engine manufacturing on a large scale is a huge undertaking. The fact they are using Mercedes's supplier for the piston, and this still happened pretty much proved the point. It is not just simply slapping some component together. Mercedes has been building engines for a long time, there are a lot of know how's involved. It would be challenging for another company to just get the same components and build it together at scale with bulletproof reliability without those know how's. Just my humble 2 cents.

[haykinson]

I don't think that all the affected engines are those they built themselves. I thought that they'd only been building them since late 2021 / early 2022, but there are affected engines going much further back. For all we know, this same issue is also affecting this same engine for Mercedes as well — it's just that engine failure there is less likely to be as catastrophic, and we don't know if it's serious enough to have required a recall. Unless someone had checked already...

A couple of other takeaways from the call:
1. Diamond will provide core replacements or prorated fixed engines for free if your engine has to be replaced at 900hrs or if it fails due to aluminum in the oil prior to TBO. They will do this regardless of current warranty limits.
2. The Diamond team wasn't aware that folks in the US have the ability to run their engines past TBO, and it sound unlikely that they will honor the above if you choose to go past TBO.

[pete423]

According to AVweb's factory tour video on DA40NG, Austro have been building the engine at least since Spring 2020.

https://www.avweb.com/multimedia/votw/a ... ght-trial/

[Soareyes]

TBR.

On a hunch I googled "Mercedes engine piston problems" and got quite a few automotive related hits. It's not just us.

[Boatguy]

A couple of other takeaways from the call:
1. Diamond will provide core replacements or prorated fixed engines for free if your engine has to be replaced at 900hrs or if it fails due to aluminum in the oil prior to TBO. They will do this regardless of current warranty limits.

There is a bit to unpack here:

a) My understanding is that they are only providing components (could be block, pistons, connecting rods, etc.) and it's your DSC that will assemble a new healthy engine from your engine and the components supplied by Austro. They are not providing a complete "new" or even refurbished engine. Is my understanding correct?

b) What is a "prorated fixed engine for free"? How do we reconcile "prorated" and "free"?

c) "if it fails". Does that mean it fails in flight? Or that the AL exceeds 8ppm?

d) All of the above applies to any Austro engine with less than 1,800hrs?

[RookieFlyer]

TBR.

On a hunch I googled "Mercedes engine piston problems" and got quite a few automotive related hits. It's not just us.

True - but I couldn't find any piston issues related to the OM640.

If anything, the OM640 seems to be regarded by spanner monkeys as reliable with good longevity, but apparently a bit of a pig to work on due to its slanted, layered and compact design, requiring the engine be lifted out for any significant work.

A common problem appears to be oil leaking from engine mounts, but other than that I couldn't find any major issues reported. One high-milage engine I watched being stripped down was said to be in very good internal condition, apart from some evidentially minor camshaft lode scouring and some noticeable crankshaft intermediate support bearing wear, thought to be evidence of perhaps lack of regular oil changes.

Of course, the automotive OM640's are way less stressed than their Austro cousins, with the three variants coming in at 80, 107, and 138 hp (OM640.940, .942 and .941 respectively) instead of 168 and 180 hp for the AE300 and 330.

Austro is no doubt on a learning curve and continuing to develop and strengthen the design based on feedback from wear, tear and failure, and hopefully this will bode well for future reliability.

[erchegyia]

Did anybody get the info when they expect this to become an AD?

[jc7204]

Did anybody get the info when they expect this to become an AD?

Attached is a screen shot from the presentation (which they may or may not make available) that they expect the MSB to be ratified by EASA in around a month and the AD 2-3 weeks later.

[erchegyia]

Attached is a screen shot from the presentation (which they may or may not make available) that they expect the MSB to be ratified by EASA in around a month and the AD 2-3 weeks later.

Thanks! Sounds like a very long time without any obligatory actions...