Viking 130 engine failure at 1150 hours

MarkH

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MarkH
(Not my video, but I like to follow aircraft auto conversions)
The link starts with an examination of the engine, the first 30 minutes are background and an engine swap.

This video came up in my Youtube feed, it seems that the engine had a custom tune for 87 octane fuel (Viking recommends 91). The cause of failure seems to be detonation.

I find this very interesting because there aren't a ton of these engines flying and, as a result, there have not been many failures. This seems to be a pretty catastrophic failure, but the engine still ran and made enough power to get back and land.
 
Auto engine conversions have proven unreliable in aircraft applications. Frankly, I wouldn’t want to fly behind any of them.

There are auto conversions that have proven reliable enough to be certificated. While I understand the hesitation to fly behind them, I believe that their development and use in experimental aviation is good for all of GA.

I am stunned that there is a Viking engine that lasted to 1150 hours

While I understand the surprise (the lack of data for high time Vikings is its own issue), I think the context is important and there is value in what can be learned from this. Something to keep in mind with Viking engines (from a data analysis standpoint) is that all of them have an unknown service history, specifically because they are sourced from salvage cars.
 
I believe the Continental diesel that Tecnam is using is based on the same Mercedes engine of the Austro when Continental took over the Thielert (sp?) debacle.

While Rotax wasn’t a car engine, it did get its aviation start in experimental planes. General Atomics gave Rotax a huge boost of confidence (and money) when they put them in the MQ-1 Predator.
 
From the FWIW department ...

Proper Corvair conversions have proven to give robust power, smooth performance, and good reliability. William Wynne has done a lot in 35 years to make these conversions what they are today. Dan Weseman (Sport Performance Aviation) has had a lot of positive developement of Corvair engines over the last 15 years even using one on his prototype single seat Panther aircraft:

1700616202649.png

Here's a list of WW only conversions that shows 124 aircraft with over 22K hours: https://www.markbaldridge.com/flyingcorvairs/
 
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just get a nice adult beverage and google the developer of the viking engine and have a fun evening reading the story.......

Best to leave that alone or we'll get a thread lock ... :eek:
 
I believe the Continental diesel that Tecnam is using is based on the same Mercedes engine of the Austro when Continental took over the Thielert (sp?) debacle.

While Rotax wasn’t a car engine, it did get its aviation start in experimental planes. General Atomics gave Rotax a huge boost of confidence (and money) when they put them in the MQ-1 Predator.
Rotax sold 50 000+ 4 stroke aviation engines so far since the 1980s ... according to wikipedia there were 400 Predator drones built so perhaps a boost in confidence but i am not sure about money …


… in their own (marketing) words…
IMG_0983.jpeg
 
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When I run into people at an airport that fly around a lot, I've never run into one running an auto conversion.

When I run into people running auto conversions, they never seem to be flying.
 
I would trade my Lyco O-235 in for a Viking engine in a heart beat, if I had the money to do so. There are thousands of these Honda engines flying now (all over the world) with very few problems after the initial gear box issues were sorted out.

There are so many benefits over the traditional aircraft engines (possible exception Rotax, ULS, maybe a few others) that there really is no comparison.

I get the fact that the collective perception is that lyco's and conti's are "real" aircraft engines. I used to feel that way myself. That was until I built my own plane with a lyco and realized that all the disparate parts from different manufacturers were all susceptible to their own install issues, maintenance issues, and failure issues (carb, magneto, fuel pump, alternator, starter, etc). And all extremely expensive.

The heart of the issue is that the vast majority of homebuilders (like myself) are designing and installing their entire firewall forward in a completely unique and one-off install. They are doing it for the first time. With the exception of Van's Aircraft, none of the kit manufacturers provide any guidance on how to install any part of the firewall forward. You have to figure out every attachment, every support, torque setting, hose and tubing connector, every wiring connector, the complete wiring system, the entire fuel system. You have to figure out every single item yourself because your aircraft is a on-off design, even if there are hundreds of similar airframes.

The odds of any of us ending up with an install any where near a certificated aircraft is small. There will be any number of mistakes, install errors, and on and on.

The idea of a simple, complete, factory built packaged system from Viking makes the likelihood of fewer problems logical.

Yes, if you took a certificated and time proven firewall forward into a homebuilt, I believe it would be more reliable than Viking system. But the reality is people like me, with zero experience, are left to try and figure out every detail, mostly in a vacuum.

Compared to a Honda engine that has been around for years and installed in literally hundreds of thousands of vehicles, the advantages are very real. Runs on auto gas, fuel injection, far more efficient, cheap to replace any part, etc..

Yet the one aspect I've come to appreciate after issues with all of the sub-components on my engine, is the the entire Honda system is designed, built, wired, and installed as a single unit, including wiring. The completely packaged system is more reliable than the lyco's and conti's when you consider the failure points of all the disparate components, and not just a catastrophic failure of the engine itself. I would also argue that the Honda engine itself is less prone to catastrophic failure than traditional aircraft engines, due to higher level of engineering and product improvement over many years.

When you consider the significant difference in range (due to increase efficiency) and the far, far lower cost of ownership, combined with Honda reliability, the Viking engine beats Lyco's and Conti's on every metric, IMO.

Also, in the case of the subject engine owner, he clearly admits to not following manufacturer recommendations for both the type of fuel and regularly exceeding max. recommended engine rpms. You can't fix stupid.
 
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Auto engine conversions have proven unreliable in aircraft applications. Frankly, I wouldn’t want to fly behind any of them.
Always hard to establish the safety record of auto-engine conversions, because FAA records don't reliably establish the number of specific engines in the fleet. About 15% of Experimental Amateur-Built aircraft are merely listed as having "AMAT/EXP" engines. There's nothing to prevent a company selling conversions as claiming the majority of those are theirs. It should be noted that one company, at least, claims an installed base that is ten times higher than the US records reflect (although non-US engines can mess up such comparisons).

In addition, there is no standardization for identifying the auto engine types. An FAA (or NTSB...) record saying the aircraft has a Great Plains conversion is pretty definite, but if the record says Volkswagen that DOESN'T mean it's NOT a Great Plains conversion.

I use two methods to examine engine safety statistics. The first completely ignores the installed base, and uses exclusively NTSB accident reports. This method computes the percentage of accidents that were caused by engine mechanical failures:
1700674816120.png

Note, again, the percentages is the percentage of ACCIDENTS, not the percentage of the entire installed fleet. This plot DOES NOT MEAN that 22% of auto engines suffer a mechanical issue, just that 22% of the known accidents were due to engine issue.

And for homebuilts, the "known accidents" issue can be important, because homebuilts are much more suited to disassembly and removal from the crash site before the local gendarmerie arrives....

Anyway, as the above shows, when accidents happen, it's about three times the likelihood that an auto-engine had an issue than a conventional engine.

However, this sort of statistic messes people up a bit. They expect to see an accident rate for the entire fleet...hence my capitalized reminders above.

I have made a stab at estimating the number of installed engines. As I mentioned, about 15% of the homebuilts don't list a specific engine. However, NTSB reports are a bit better. I cross-referenced the list of AMAT/EXP engines in the FAA registry with the NTSB reports, and got the engine types for about 150 AMAT/EXP engines. I use that data compute the estimated percentage of the AMAT/EXP fleet that are particular engine types. It's done for both the active aircraft as well as the de-registered ones.

Here's what the auto-engine conversion numbers look like:
1700675666784.png
About 10.24% of the AMAT/EXP engines in the crosslisted NTSB list were VWs, so I applied that percentage to the number of AMAT/EXP engines in both the active and deregistered aircraft list to compute the estimated total number of installed engines. Note that there have been about four times the number of homebuilts with VW engines than the current registry reflects. Other types do not see as much of an increase.

For comparison, here's the same data for Lycoming:
1700675983129.png

With that, I can estimate how often a given type of engine fails in a given year (for homebuilts):
1700676175738.png
It's not on the graphic, but the worst-case I saw was a common two-stroke engine, with an installed base of ~780 engines and a 0.245% annual failure rate.

Now, consider how "serious" the failure rates are. The Honda, for instance, has a ~0.15% annual failure rate...ZERO point 15 PERCENT. That's one accident each year for ~600 aircraft. My 22-year accident database shows only 9 accidents where the Honda engine was a causal factor. That's really not that bad.

Of course, my processes have their issues. I examine homebuilt accidents from 1998-2021, for example, and the aircraft in the deregistered list may come from far before that time period...makes the results a bit better.

Also, based on the percentage of the number of accidents (the first graphic), the Rotax 912 and the Continental O-200 come out about the same. But as you can see in the last graph, the 912 is higher than the O-200. The Rotax fleet size is difficult to determine, since not only are there engines listed as AMAT/EXP, there are listings showing generic "Bombardier" or "Rotax" engine types without a specific model. These could be 912s, and equally could be two-stroke 582s. I have run a similar process to try to identify the Bombardier or Rotax engine types.

Ron Wanttaja
 
There are thousands of these Honda engines flying now (all over the world) ...
Please provide proof. Get me a list of N-Numbers (and registration numbers for those outside the US). I estimate about 250 in the US.

I went through this with Corvair engines a year or so back. One of our happy crew provided me with a list of Corvair-powered engines and I was able to calibrate my fleet-size-estimating process.

Ron Wanttaja
 
It seems the owners of the latest generation Viking engines are pretty happy with them. It's really hard to tell what the success rate is because of all the background noise from people who have a sour taste for the companies owner. As with all new engine applications there will be growing pains sorting out the different failure modes. The 912 certainly wasn't a success right out of the gate and originally had like an 800 hour tbo. VW's took decade's to sort out if you'd even say they are now, same goes for Corvair engines. The Subaru conversions have always sucked, the engine wasn't all that reliable in a car much less an airplane. The Apex engines have had their own gearbox and engine problems as well. Hopefully one of these companies have the staying power to keep fine tuning the application into a genuine alternative.
 
The majority of auto installs are one offs done by someone of unknown experience level. my auto engine plan is to use an unpressurized coolant system with electric coolant pumps. if it fails does that mean all auto engines should be considered unreliable or that my specific installation was not thorough engineered?
 
When I run into people running auto conversions, they never seem to be flying.
I flew about 200 hours over 4 years behind the Mosler half VW in my Fisher 404. Other than valves that needed grinding (which has also happened on my Lycoming), the only engine related troubles I had was with the Slick magneto. The guy in the hangar next to me had a Corvair powered Zenith CH601, and he flew it a lot. Now I'm sharing a hangar with another guy with a Corvair powered Rebel. I don't see it flying because we're on different schedules, but I know he recently finished his 40 hour test period.
 
How do you know owners are happy with them or that they arent having failures and issues not reported through an ntsb accident report?? The developer highly moderates his own forum and a few others as a moderator to delete anything negative posyed and has gone after other builders who tried to start their own forum to discuss the problems they were having. He isn't a person I would trust to design something that could kill me if it stops working at the wrong time.
 
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