Cylinder head cracks

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Greg Ball

Cylinder head cracks

Post by Greg Ball »

Tagging on to the question of why not - why not rebuild the core etc. One thing that is really troubling me about the airplane/ engine combination which otherwise seems perfect for me and my experience level: Is whether this has anything to do with the cracks that the NTSB found at a flight school (adjunct to an accident investigation) between the intake and exhaust values of it seems almost every cylinder or every NG they had. Diamond reported said it was unrelated to the accident, fine, and didn't affect the engine's functionality...

But the reported cracks plus more or less treating the old cores as rubbish, is not a combination that makes me feel comfortable. In one sense, I'd actually prefer replacement anyway, if you have the funds. But I'd also want to have all reasonable confidence in the engine throughout its lifetime.

I'd love for someone to tell me I'm concerned over nothing, increase my comfort and such.
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Re: What to do with that old Austro engine

Post by Boatguy »

Greg Ball wrote: Mon Mar 28, 2022 11:48 pm Tagging on to the question of why not - why not rebuild the core etc. One thing that is really troubling me about the airplane/ engine combination which otherwise seems perfect for me and my experience level: Is whether this has anything to do with the cracks that the NTSB found at a flight school (adjunct to an accident investigation) between the intake and exhaust values of it seems almost every cylinder or every NG they had. Diamond reported said it was unrelated to the accident, fine, and didn't affect the engine's functionality...
Can you please post the document or a link that is the source of this finding?
Greg Ball

Re: What to do with that old Austro Engine

Post by Greg Ball »

Sure, here is the link to the NTSB final:

https://data.ntsb.gov/carol-repgen/api/ ... /94574/pdf

I'm not sure if a link from my search results is transferrable like that, so the NTSB Docket is: ERA13LA043 The accident was in Palm Coast Florida on 10/11/2012 and the report with the other references came out 06/11/2014. You have to read down into the document further towards the end to find the other cracking references. I had just searched for make "Diamond" and model contains "NG"
Greg Ball

Re: What to do with that old Austro Engine

Post by Greg Ball »

Apologies, I gave the wrong accident information. The link is still correct. But the other information is that the accident was 12/29/2016 and the report on 07/15/2021 with a docket of WPR17LA050 which occurred in Kingman Arizona.
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Re: What to do with that old Austro engine

Post by chili4way »

Thread drift, even if interesting.
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Re: What to do with that old Austro Engine

Post by Boatguy »

Greg Ball wrote: Tue Mar 29, 2022 2:44 pm Apologies, I gave the wrong accident information. The link is still correct. But the other information is that the accident was 12/29/2016 and the report on 07/15/2021 with a docket of WPR17LA050 which occurred in Kingman Arizona.
Worthy subject. I suggest you start a new thread.
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Re: Cylindar head cracks

Post by Chris »

Split into a new thread
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Re: Cylinder head cracks

Post by pietromarx »

That report makes for some interesting reading. The NTSB looked into this much more than I have seen for other similar incidents (no injuries, etc.).

<ThreadDrift>
The report will certainly add some fuel to the Austro vs. Lycoming conversation.
</ThreadDrift>
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Re: Cylinder head cracks

Post by chili4way »

Tagging on to the question of why not - why not rebuild the core etc. ... Is whether this has anything to do with the cracks that the NTSB found at a flight school (adjunct to an accident investigation) between the intake and exhaust values
There is no relationship between this event and Austro's decision to discontinue its overhaul service. (That unfortunate decision appears to be strictly labor optimization for engine availability.) The reason there can be no relationship is that the cylinder head is replaced during an overhaul. Recent overhauls would use the new, stronger version that was developed to withstand the additional stresses of the AE330 engine. This is what will come with replacement engines. The core (i.e. the cylinder block) isn't cited as an issue in the report. The initial issue was due to a piston failure that appears to be have been caused by a maintenance-induced failure (MIF). Some of the other cases cited suggested issue induced by coolant loss.

From page 12 of WPR17LA050:
During the investigation, cracks were observed within the combustion chambers bridging the intake and exhaust valves of cylinders Nos. 2 and 3 (see figure 6). Review of the other Austro Engines-investigated events revealed similar cracks in all three engines. Representatives from Austro Engines stated that the cracks in the cylinder head, “are not expected to restrict the functionality in any manner.”
To be fair to the OP, the term "combustion chamber" could make it sound like the cylinder block was involved, however, the valves and the cracks cited in the report are located in the cylinder head that would be replaced during the overhaul.
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Re: Cylinder head cracks

Post by UglyBuzzard »

Thank you chili4way!

The OP is now "UglyBuzzard" BTW. I very much love seeing that there is a stronger head coming from the AE330 at replacement.

FWIW, to the comment that the NTSB looked into this more than usual, the report says: "... a complete examination was performed under the supervision of the Austrian Civil Aviation Safety Investigation Authority. A series of examination reports were prepared by
Austro Engines and independent testing facilities..."


Yah, I wasn't too concerned about the FOD damage, it was the more systemic "bridging cracks" (I think is the correct term) and the cooling system pressurization from a different crack.

In no way do I have any expertise, but being concerned enough to try and learn something I did some more looking. In some SAE papers I found, it appears that bridging cracks were a bugaboo in the development of diesel auto engines because they were something that appeared to depend on the individual application. In other words (if I'm interpreting right) it was especially irritating to the designers that what was working fine in one type of vehicle or application could be a problem in another due to external differences like temperature, mounting, usage, etc. If there is any truth in that, then this might be a somewhat expected (or at least not completely surprising) teething issue that Austro would have an eye on, discover over time and resolve.
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