Engine Reliability?

[EdW]

I'm a long way down the road from considering a powerplant, but was wondering, with all the discussion regarding the AeroVee, how does the reliability of this unit compare to the Revmanser, or the Hummel? What about Great Plains? Is the problem with the basic engine, or with the mods/accessories installed? Anyone out there done any basic research on the various engines?

ED

Just east of Graceland

[Gordon]

VW Reliability..........?

Ed.........In regard to your engine reliability concerns.........you are not alone on that one. I am using a Hummel engine built by Scott Casler in Coolidge, Az. He is a professional engine builder, when the engine is finished, he puts it on a stand and test runs EVERY engine before shipping them. That is worth something in my book. Revmaster does the same.

The AeroVee may well be a good engine IF assembled EXACTLY right..........but....if this is your first engine build you may miss one small thing that will come back to bit you later. That could be fatal.

I compare "first time" engine builders to "first time" airplane painters.........you will not likely get "show quality" the first time. When it comes to engine reliability...............I want that "show quality" the first time........I may not get a "2nd chance" it my luck turns really bad.

Just saying............

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

[kmacht]

I haven't tried to do that type of search in about a year but the last time I did it was very hard to get any sort of statistically valid data. The ntsb usually lists the engine type as other. Sometimes they list a manufacturer but not often unless it is a variant of a certified engine. You can sort of get the data for an aerovee by cross referencing the accident information to the sonex completion list where a motor is usually specified but not always. Since remaster and great plains don't manufacture aircraft it is harder to parse out.

As to the mention of doing a test stand run, that does give you some additional confidence but the majority of aerovee accidents aren't in the first few hours of the engines life. Had you put the aerovee on the same test stand before flying it is unlikely you would have found anything wrong.

It is my opinion (and only an opinion) that fuel delivery might have something to do with the glut og takeoff accidents. We have been living with the "burps" for years on the sonex/aerovee motors. People have installed burp tubes, removed gascolators, insulated fuel lines, etc all with some success but a root cause has yet to be found. No matter whose engine you choose I would recommend spending just as much time as you did researchimg the engine thinking about what to use for a fuel delivery system from the tank, the fuel line, filter, and the carb. The best of engines won't run without fuel

Keith
#554

[samiam]

I'm not an Aerovee owner/flyer (I'm putting a Corvair in my Sonex), but I find it disheartening to see the negativity that has come about lately about this little engine. I'll be the first to admit to some concerns about the turbo model - I would be reluctant to personally pursue it at this time. However, the NA Aerovee has had an excellent history of success. It has a great price point for budget minded builders. Additionally, it confers the outstanding benefit of being able to build it yourself from a kit.

Some will see building it themselves as a drawback; for them, other companies offer a factory built option. But for those who want the experience of building the entire airplane and understanding the engine, it is wonderful that they are able to experience that.

[Waiex 49]

Having followed this forum for quite a while, it seems there are a number of people who don’t agree with your opinion that the AeroVee “has an excellent history of success”.

Too many crashes from engine failures, in my opinion.

[EdW]

Having followed this forum for quite a while, it seems there are a number of people who don’t agree with your opinion that the AeroVee “has an excellent history of success”.

Too many crashes from engine failures, in my opinion.

This is what I'm getting at...How do we know that the AeroVee is more or less dependable than any other? This is the empirical info I'm interested in.

I fly a Piper Apache. It is the sweetest, most comfortable airplane I've ever flown. BUT! It has a reputation for being a mean,nasty uncontrollable beast at low speed. How did it get this rep? "My wife's aunts brother in law heard a conversation between two bar maids, and they said that..." So, I take all those stories with a HUGE grain of salt. By the way, any airplane will do you bodily harm if you let it get away from you.

As far as building the engine, I've been an A&P for sixty two years, and formerly ran an engine shop, so I'm not reticent about my build-up skills. I just want facts, not rumors, innuendos and theories. Is the VW engine reliable at the speeds we operate it? What is the mean time between failures? Are those failures the engine itself or those items we've bolted to the case. What items have a high failure rate?

Ed

OK, I've got my drone license...when does the season open, and what's the bag limit?

[daleandee]

This is what I'm getting at...How do we know that the AeroVee is more or less dependable than any other? This is the empirical info I'm interested in.

I'm not certain that actual empirical data exist to answer the question. I drive a an air-cooled VW beetle and it has been very reliable. Having said that ... I'm not asking the engine to put out much more power than the cooling fins on the heads were ever designed for and it wasn't built out of aftermarket racing engine dune buggy parts by an amateur builder with a prop on the end of the crank. I'm not saying the Aerovee is a bad conversion but this is where it's at. There have been a number of builders that have used VW engines very successfully in single place airplanes with smaller displacements (1835 works well here). Now the little VW engine is being tasked with more displacement and more work. There has to be a reasonable limit to what this small engine can be expected to do. When builder's talk of flying two up on a hot day at climb rates of 200-300 FPM the little engine is taking a beating and life expectancy suffers. TANSTAAFL!

Below are my thoughts given on another thread that reiterates the point I have been trying to make for a long time:

For the basic budget builder I do think the Aerovee is a good beginners option. No doubt the little VW engine works very hard in a two up environment but the original intent (at least I believe) was to build a light weight tail dragger airplane that had good performance on reasonable power. Now that we are building them with so many wonderful things we like and they are closer to 700 lbs empty than the 600 or less that was intended ... we fault the little engine that could and want something larger. I stand guilty as charged. My 650 lbs nose roller needed more than the VW could provide. The tail wheel with 120 horses is a blast to fly. Of course it's not welcomed anywhere near a company represented function but I'm OK with that.

Again ... for a light weight tail wheel airplane with small payloads on cool days the little VW engine can work if you keep up with the head & valve maintenance. As far as the Aerovee itself is concerned ... I'm a fairly good mechanic but when I opted for the Corvair on my Cleanex I had it built by a man that knows & builds Corvair flight engines for a living. It was well worth the cost to do that. Perhaps Sonex should consider hiring an excellent engine builder so that they could then offer an assembled core engine to take the guess work out of the engine build for those that desired to do so. But then there is that liability thing that no one wants to touch ...

Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
Signature Finish 2200 Paint Job
171.2 hours / Status - Flying
Member # 109 - Florida Sonex Association
Latest video: https://www.youtube.com/watch?v=1VP7UYEqQ-g

[Rynoth]

Ed, you're asking a very good question that I don't believe has a very clear answer. This is, in the end, a voluntary builder forum and, as such, represents a vocal minority of those who actually build/fly Sonex/Aeroconversions products. I don't say this to discredit the value of this forum, but as you already pointed out, there are a lot of rumors, innuendos and theories that, in the absence of industry-standard statistical data, are indeed simply the opinions of those who post them.

[NWade]

In addition to Ryan and EdW's points about data vs. stories, its worth pointing out that plenty of Continental and Lycoming engines have failed over the years, from just about all of the things that have taken down Sonexes (i.e. something goes wrong in the fuel system and the engine stops turning, a rod-end comes apart and the rod puts a hole in the case, an assembly error results in sealant plugging up critical oil-galley holes, etc). The turbo is the only unit that seems to have problems that manifest in the form of consistent symptoms across the board (namely the coked oil in the center bearing and a stiff/frozen turbine as a result). Well, that and the Nikasil cylinders that had a tendency to mushroom or roll over at the end as the head bolts were re-torqued.

Beyond those two items, I haven't seen a pattern of the same part failing in multiple engines. Can anyone else point to a series of accidents or engine failures across multiple airplanes, where the same part appears to be at fault?

--Noel
Sonex #1339, AeroVee Turbo being ground-tested & tuned

[radfordc]

It is my opinion (and only an opinion) that fuel delivery might have something to do with the glut og takeoff accidents. We have been living with the "burps" for years on the sonex/aerovee motors. People have installed burp tubes, removed gascolators, insulated fuel lines, etc all with some success but a root cause has yet to be found.

I think the root cause is proven...it's bubbles in the fuel caused by hot gas vaporizing in the fuel line. When these bubbles reach the Aerocarb you get a "burp". This happens most often with Mogas and especially when running "winter blend" that has a lower vapor pressure.

The reason you don't hear about burps in other engines is that very few use a metered flow system like the Aerocarb. A carb that has a bowl won't burp because the bubbles go away in the bowl. A fuel injected system won't burp because the fuel is under pressure all the way to the cylinders so that bubbles can't form.

The solution to the burps in the Aerocarb/Aerovee is to either prevent bubbles in the first place (100LL, insulated fuel lines) or to let the bubbles escape before they reach the carb (burp tube).