I Love My AeroVee

[mike.smith]

Now that I've assembled and run one, if I were to do it over I would strongly consider buying a complete and running engine instead. Knowing that someone with expert VW experience assembled the parts and ran them at their facility is a lot more confidence-inspiring (and a lot less frustration-inducing) than finding out that I've been shipped a bunch of parts that no one inspected before sending them out to a customer.

Noel:

Very good post. Now that I have more experience with the VW I understand all those things better. Except for the Nickasil cylinders, I seemed to have gotten good parts back in 2012.

It took me 3 months! to put my VW together the first time. I didn't complete anything without thoroughly understanding it first. Not because I wanted it that way; just because I was nervous (scared?) about every step, and getting it wrong. Having a third party VW books was essential, as even Sonex notes.

When I replaced my failing Nickasil cylinders it took me only 1 month to rebuild it. When I had a prop strike and replace the crank, bearings, etc, it took me 2 nights to tear it down, and 2 nights to put it back together. It's run stronger than ever since then.

I know my engine inside and out (literally and figuratively). I LOVE knowing my engine inside and out. I can fix or replace anything, and I'm as good as an Indy pit crew in removing and re-hanging an engine. Like I said previously, with my small tool kit I can fix most anything, and can almost rebuild the darn thing at a remote airport.

So for me, I would rather build an engine than buy a running one. For my next building project I plan to buy a run out O-200 and learn to rebuild it. But of course that's just me. Building an engine isn't for everyone. But it does have its up sides to be considered :-)

[Fastcapy]

Mike Smith, you are correct about it being nice about knowing the engine so intimately. I know I personally had more hours invested in just prepping the case and parts for assembly than they advertise as assembly time.

I to think it is imperative to use other sources when building the motor. The VW book and The Samba were great resources as were some of the VW guys out west who I was able to chat with. Without that extra guidance I think I would have given up on mine.

I think the issue for a lot of people is they buy it as a kit and expect the components to be fully tested, not just ordered from whatever source has them in stock and not verifying the fit and function of the parts. This lack of QC is seen in stuff like the Nikasils, the Mofo heads and other stuff. If you expect and anticipate the issues you can make it work, however if I was to build another Sonex I wouldn't put an Aerovee on it, even though I have a good grasp on what needs to be done to get it running to my overly picky standards.

[peter anson]

I found it really interesting reading about Mike Smith's experience of how working on his engine gave him so much extra confidence not only in his engine but in his ability to repair faults, because his experience exactly mirrors my own with my Jabiru 3300. Like Mike, a few years ago I had a prop strike. I called Jabiru and they recommended a bulk strip (A$8000) and a new crank (A$2000). Any extras would drive the price pretty close to what I paid for the engine so I decided it was time to learn about Jabiru engines. It was a good decision as I found that the engine was quite straightforward to work on. I think that I eventually spent about A$2700 but that covered the cost of several engine upgrades, one major improvement and a couple of repairs to things that were going to cause me problems in the near future. (But I would still prefer an engine that has been test-run.)

Peter
Sonex 894 350 hours - 160 hours since prop strike

[tom0nex74]

Mike Smith hit it right on the head. It does what it does pretty darn well Get the areo-injectror tuned with the right needle, then its all throttle and mixture to whatever parameters you want. Replacement parts available at your local VW dealer. Mike.......if you got 20 more HP you'd be looking for 20 more.......Tom Ryan 0nex 74

[mike.smith]

Mike.......if you got 20 more HP you'd be looking for 20 more

No doubt! But with hills and trees all around me in New England, just 20 hp extra would sure make life better! :-) But I'm not gonna' get 100 hp for $8K! :-(

[lutorm]

I am by no means an expert, but I understand engines and am not intimidated by them.
...
With any of the VW conversions that don't come to you as already assembled and test-run, you need to treat it like a second "homebuilt" project you are taking on.

This is exactly right.

If "kit" brings to your mind a match-drilled quick-build RV or something where you rivet it together and go, I think you've got the wrong picture. (Maybe "kits" are too good these days?) Think of it more as the kind of experimental airframe "kit" that is a bunch of half-fabbed materials and a set of plans. You wouldn't go at such a kit by just starting to follow the instructions. No, first you make sure you understand the whole thing, learn the fabrication methods used to make sure you can do airworthy work, talk to other people who have done built them, learn about the design, learn about upgrades and modifications people have come up with since the design was created, etc, etc. That's more like the kind of kit the Aerovee seems to be.

I don't mind that. But like Noel said, you have to understand engines and not be intimidated by them. And I would add: know the basic tools and procedures used in engine shops. If you follow these steps, I don't see any reason you'd end up with a less airworthy product than if you built that airframe. As always with amateur work, you have to substitute your lack of experience with extra care. (But I'm sure as hell not going to trust my engine work to fly around without first boring circles within gliding distance to the airport at full throttle for a substantial number of hours, that's just common sense. For any engine. Airplane piston engines are all ridiculously unreliable.)

It seems people have a psychological hangup about engines. They're really nothing different from any other project. If you don't trust your workmanship, don't do it. That applies to an airframe as well as an engine. If you don't make 100% sure you understand how to build that airframe, you could end up with any number of catastrophic airframe faults. People seem to be OK with that risk, but not that of the engine stopping (which scares me less than stuff like losing control surfaces, jamming controls, asymmetric flap deploy, etc). If you fly SE piston aircraft enough, you will have an engine go out, that's just statistics. Even if it's a Lycoming. You have to be OK with that basic risk.

Edit: Just to be clear, I don't even think Sonex is doing anything wrong (except possibly overly optimistic salesman talk.) I don't doubt that they've tried and tested the Aerovee design to the best of their ability. But they're a small operation, and any testing they reasonably can do has little chance of uncovering all the possible problems that may occur 1% of the time. But with many hundreds of Aerovees out there, people will hit those edge cases. That's also just statistics. Compare that to the number of miles auto manufacturers put on their engines in testing to achieve their reliability numbers.

[kmacht]

For those of you who believe that paying attention to detail during assembly will give you a reliable aerovee engine, how do you square that against the fact that two factory aircraft had their engines fail on takeoff with disastrous results? That is what is really bothering me about my aerovee. I could live with the limits of the lower horsepower and climb rate but if the factory can't build and run engines reliably, how is the average builder supposed to believe that they can? The fact that those accidents come to mind every time I fly my airplane is the reason I am selling my aerovee. It has never stumbled or given me a reason to doubt it in flight but the fun in flying has been taken away because I just don't trust it or the factory anymore. For others the risk/reward might still be there.

Keith
#554

[Gordon]

The AeroVee Love Affair.........?

Noel........you comments are well taken......I agree. I bought my VW engine from Scott Casler (Hummel engines) in Coolidge, Az. He is a professional engine builder and hopefully scrutinizes the parts prior to assembly. Once assembled, he runs the engine in a test stand. That gives me a certain amount of comfort. My engine cost me $7075.00 (August 2017 price) so it's not like it cost MORE than the AeroVee "kit engine". If nothing else, this speeds up the "first flight" date because I didn't have to spend 3 months building the engine......just saying.

I especially like Dale Williams comment......."my aircraft engine should run AT LEAST as good as the truck I drive to the airport"..........well said for sure. I drive a 2014 Silverado with a Duramax diesel.....nuf said.

Any comments from the Revmaster or Hummel engine flyers? Would love to hear your feedback.

Gordon.........Onex........Hummel 2400

[Stogie6]

I am in the middle of reading the book “How to rebuild your Volkswagen Air-Cooled engine” and found a passage on page 117. Bottom left of page, More Patience.
Just sayin’

[NWade]

For those of you who believe that paying attention to detail during assembly will give you a reliable aerovee engine, how do you square that against the fact that two factory aircraft had their engines fail on takeoff with disastrous results?

Keith -

Emotion and confidence are tricky things and I don't know that any one logical explanation can change someone's position (...and I'm not saying that it necessarily should). For myself, as someone who's had problems with the engine parts I was given to assemble into an AeroVee, I consider the following things:

1) Every engine on an aircraft has failed at least once or twice. Lycomings and Continentals have been the reason why planes have crashed. ADs and Service Bulletins make it plain that there is nothing magical or bullet-proof about their design - plenty of weaknesses and improper parts have been identified in those documents over time. Their long legacy means that there has been more time for all the engineering to be vetted and many weak points addressed, and we shouldn't completely discount the earned wisdom due to their legacy/history. But at the same time they are still complicated devices with many moving pieces that experience stress, fatigue, and neglect and therefore have had (and will continue to have) failures.

2) There are a few hundred AeroVee engines out there, but they aren't regularly falling out of the sky - if they had major failures on a frequent basis, we'd hear about it. There are plenty of stories of people running into problems during assembly or early running of their engines - some due to parts problems and lack of attention by suppliers, some due to poor assembly by builders; but far fewer stories about people making off-field landings and trashing their aircraft due to an in-flight failure of the engine. You don't see NTSB or Kathryn's Report links to AeroVee-powered airplane accidents popping up on a regular cadence every week or every month.

3) The Turbo failure / crash happened back with v1 of the Turbo installation - one which we know exacerbates heat-soaking of the turbo after shutdown and hence lots of potential for oil coking / turbo seizing. And as the NTSB pointed out, had they chosen to make a full-runway takeoff instead of an intersection takeoff the outcome might have been a whole lot different. I say this not to disparage the departed, but to point out that it was a confluence of multiple factors - not just the engine - that resulted in fatalities. Our opinions & emotions are often shaped at a high-level by outcomes, rather than examination of what went wrong and the processes that led to the outcome. The improved turbo system today appears to be better at dealing with the oil coking problems; but still isn't perfect and requires close observation/maintenance. I know several Turbo owners who've removed the system and are very upset at the deficiencies of the original design and the apparent lack of expert knowledge and testing (especially vis-a-vis longevity and reliability) - but most of these same people are still running the engine as a normally-aspirated AeroVee and they haven't switched to an entirely different powerplant. I think that says something about the underlying system being adequate for our purposes.
(Side-note: as someone who bought a turbo kit in late 2016, I eagerly await the reveal of the prototype water cooling system that Mark mentioned on the forum here a couple of weeks ago. I hope it is available before I have put many hours on the engine as I feel that it is important for the long-term viability of the Turbo system).

4) As for the crash of N12YX, I find several things notable. First, the NTSB did not inspect the scene of the accident. Second, there is no mention of the NTSB checking the carb system - which I find interesting given the change in engine sound, drop in RPM, and action by the instructor to fiddle with the mixture control at ~200 ft AGL. Personally, in a moment of surprise during the early ground-testing of my engine, I accidentally yanked my mixture cable loose (as I hadn't secured the cable as strongly as I should - I focused too much on making sure the control swiveled smoothly and not enough on the cable being firmly locked into swivel by the set screw). So I wonder if something on the carb came loose on N12YX? We'll never know. But the point is that all the NTSB report mentions is low compression on 2 cylinders and 2 exhaust valves that were worn. We don't know *which* 2 cylinders. We don't know what the compression was. Famed A&P Mike Busch has shown that low compression on cylinders don't usually cause much of a loss of power (he has EAA/AOPA webinars & articles that go into this in-detail). But we don't know to what degree the exhaust valves were leaking/failing; which may have been a more severe problem than just leaky piston rings or a grooved cylinder bore allowing blow-by. We don't know what the fuel situation was, or whether this might have been fuel-flow related. We don't know how recently the engine had been run or how frequently it had been run over the past 12 months (engines like to be run regularly to keep moisture and corrosion levels low). We don't know when its oil was last changed, when it got its last compression check or borescope inspection, what the spark-plugs looked like, whether a spark plug wire got melted by an exhaust pipe, whether the intake manifold had developed any leaks, and on and on... The loss of power was sudden; but the underlying issue may have been a slow creeping problem that could have been detected earlier. We just don't know. However, if it was a major deficiency in the design of the engine there's no reason for Sonex to keep that a secret. Doing so would only lead to much worse repercussions (for the business and in terms of legal liability) later on when word got out or evidence mounted that this was a common problem. And the only (non-Turbo) service bulletin that appears to have been issued within a few months of this accident is the one stating that fully synthetic oils should not be used. An important SB to know and to heed; but not any kind of indictment of the engine itself.

5) Of the AeroVees that have failed, we haven't seen a consistent failure of a single part, or within one specific section of the powerplant system. If there was a major flaw or weak point in the base AeroVee, we'd expect to see the same problem identified repeatedly in accidents or teardowns of engines (witness the seized turbine in the Turbo engines, which definitely appears to be a common thread across several of those failures). Since we don't see that commonality in parts failures across the AeroVee lineup, it lends me confidence that the core of the system is adequate for the stresses / loads that we put on it.

Having said all that, I can identify with your comment about some of the fun being taken out of it. Frustrations with receiving improperly machined and non-QC'ed parts have had an impact on me. Personally, I have resolved _not_ to obsess over the money I've already spent or the time I've sunk into dealing with issues - because focusing on that isn't going to get my plane in the air or make sure its safe for my wife to fly. What I choose to do instead is focus on ensuring that every step I take advances me towards a safe, flyable airplane. And I keep that "mission" in mind whenever I look at a part, assemble an item, or weigh the validity of the factory's documentation/advice/responses.

Take care and best of luck,

--Noel