Aerovee Concerns/Clarifications for a Newbee

[radeluca]

HI everyone, I am new to the site. I am excited because I just received my set of Sonex plans. I plan to scratch build. I had made up my mind about the Aerovee engine. I really like it, and that is what I want to use. I have been doing some research on it and have come across many different opinions. Some say it’s a good little engine, and others say otherwise. Being new I am looking for some clarifying answers. I am sure this subject has been thoroughly discussed, and I apologize if this is the wrong place to talk about it. I apologize that this is long, but I really want some feedback.
I have done some research on the NTSB website, and have looked for incidents/accidents involving Sonex aircrafts with the 80HP Aerovee engines. I am excluding all the Jabirus, Revmasters, Hummels, Great Plains, Turbo Charged, Others, etc. Also, I am excluding any incidents/accidents regarding fuel starvation, weather related, pilot not properly controlling the aircraft, density altitude, etc. These are strictly 80 HP Aerovee Engines that had some sort of mechanical malfunction. These are sonex airframes (sonex, waiex, onex) I found:
N478SX Crankshaft failure
N184L Loss of Power Unknown Reasons
N997KK Loss of Power Unknown Reasons
N1006N Loss of Power (Not adjusting valves)
N18YX Loss of Power Unknown Reasons
N198PC Loss of Power Unknow Reasons
N634SX Loss of Power Unknown Reasons
N732SX Spark Plug Popped Out
N461MM Loss of Power Unknown Reasons
N7035Z Crankshaft Failure (had previous prop strike)
N393X Still Investigating
N1950J Still Investigating
N12YX Still Investigating
Based on the above, I can see that 6 of them were the result of some engine malfunction with undetermined reasons, 3 are still under investigation (I am assuming these are 80HP Aerovee powered), 2 were crank failures, 1 was a spark plug popping out, and 1 was not adjusting the valves as directed. With this info, these are the questions I have:

1) Have I mistakenly left out any other incidents/accidents involving 80HP Aerovee failures on Sonexs that anyone knows about that is on the NTSB website but that I have left off? Have I mistaken the reports based on the N numbers and cause of accidents above (basically correct me if I am wrong on the list above)?

2) Is there documented evidence of other 80HP Aerovee powered Sonex accidents in other countries that was a result of the engine failing? Is there documented evidence of 80HP Aerovee accidents on other airframes besides Sonex both here and abroad that was a result of the engine failing?

3) Regarding crankshaft failures, I can see there are 2 documented, but to be fair I am only counting 1 since the second one previously had a prop strike and the crank was not checked, so it doesn’t seem fair to count that one. I have read a few forums and people make it sound like it happens all too often. I read one person’s post and said it happened to them too, and another saying he knows someone that it happened to. My questions is, why was it not reported? I couldn’t find anything on the NTSB site. Is this happening to people, and not being reported? Is there documented evidence both from here and abroad on this happening on either the Sonexs, or any other airframe?

4) I have read that there are about 1000 Aerovees out there. Can anyone shed some light on this if that is accurate? I don’t want to sound insensitive because 1 crash, 1 loss of life is 1 too many. But if it is only the above list, and there really are 1000 of them, it doesn’t seem like it has a very bad failure rate. I know that 6 are the result of engine failure with unknown reasons (that’s scary), 3 are under investigation, and 2 seem to be result of engine failure due to improper maintenance procedures. Again, I will want to get all the facts as possible to make a good informed decision.

5) OK, this is for your guy’s opinions. I like the looks of the Aerovee 80HP, and it seems like an easy to assemble and easy to maintain engine. For those who fly behind or have flown behind the the 80HP Aerovee, what would you say to a newcomer? Have you had personal experiences such as engine failures, crankshaft failures with the 80 HP Aerovee?

I am sorry it is soo long, but I am new and just want to get as many facts as I can to really make a good informed decision.

[kmacht]

The first crankshaft failure was due to the builder incorrectly pushing the prop hub back off without supporting the crank after it didn't install all the way down the first time it was assembled. Sonex has provided details on to to properly remove the hub and now also sells the crank and hub as as pre assembled option.

Keith
#554

[SonexN76ET]

You bring up some very good points. What bothers me are the loss of power for indeterminate reasons.

Besides the power losses you list there are a few more that did not make it to the NTSB reports due to being able to land with no damage or injuries. Two were due to faulty throttle cables/linkages and one was due to a valve rocker arm breaking. Another one due to inadvertently using auto gas with alcohol that caused the fuel lines to swell and restrict fuel flow.

The spark plug popping out was clearly a maintenance error and could have happened on any engine.

The throttle cables have been substantially upgraded since those incidents regarding throttle cables occurred.

We do not know the cause of the broken rocker.

There are losses of power for indeterminate reasons in the NTSB reports on many types of engines and it is not unique to the Aerovee. Suspected items that can cause this in any engine are vapor lock, water in the fuel system, carb ice, improper engine leaning, ignitions grounding out due to faulty wiring, fuel flow blockages, induction system components leaking, fuel vents getting plugged, and incorrect carburation settings. I am sure there are other gremlins out there. Most of these risks can be minimized with using proper proven installation techniques.

The thing that differentiates the Aerovee from other widely used aircraft engines is that we build them ourselves. We also make the choice in which fuel lines and engine controls to use. We make the decision on fuel line routing. We decide how close to let our fuel lines come to the exhaust pipes. We decide what type of induction to use. There are numerous variables and some compound variables in each installation and engine build.

I have flown a 2,200 mile cross country with my Aerovee. While I did it, I would have been more comfortable flying with a certificated engine. In my opinion you need to be an engine guy comfortable working on engines to be completely comfortable with building your own engine. It is not for everyone. That being said, I in reality I could not and can not afford to own and operate and maintain a certificated aircraft engine. So I maintain my Aerovee with precision and fly conservatively and always have a plan for an emergency landing. It has performed well over the past two and a half years for me.

Thanks,

Jake

[wlarson861]

The AeroVee is a great engine but you have to be a "fiddler". I have spent a lot of time adjusting the engine and tweaking it for best performance. As far as replacing it with anything out there on the market though every other option is an experimental engine. I upgraded to the turbo and would highly recommend it for a guy building new. The downside to an AeroVee or any VW derivative is the amount of time you spend adjusting the valves etc. With certified engines they seem more set and forget but there are no certified engines that fit into the Sonex. I am enamored with the new UL engines for their FADC design but the cost is prohibitive to me. For a legacy Sonex I would go AeroVee turbo. for a B-model I would probably day UL. My 2 cents worth.

[Onex107]

The Aerovee is a proven engine, but, it must be assembled, adjusted, and maintained by you. Owning and flying a certified airplane has a system (FAA) that takes that responsibility out of your hands. You depend on the reputation of the manufacturer and service bulletins generated by "reported" problems and if severe enough they become mandatory AD's that your mechanic must comply with. You have very little to do with it. The engines are basically no different, just heavily regulated.
The Aerovee requires you to assemble it, adjust it, preflight it, and fly it right out of the box. No test cell time to measure and adjust output before leaving the ground. Static rpm run ups are all you get. High break in temps., timing, and AeroInjector adjustments have to happen before or after the first few flights. You must be familiar with the operation of the engine.
Every 25 hours I do the equivalent of a 100 hour inspection. Change the oil, clean or replace the plugs, adjust the valves, do a compression check, re-torque the prop. This only takes a few hours but I know my engine intimately and there will be no surprises. That's what it takes for me to have confidence that it will perform as expected. As Bill said, the Aerovee is the type engine that must be fiddled with. If you do not want to do this, consider buying an engine that has been factory assembled and test run. For a significant increase in cost you have eliminated those two things. You must still maintain it or find someone familiar with the brand that you can rely on.
The advantages of the Aerovee are low initial cost, maintenance expenses, and overhaul cost. And, the Soex line was designed with that engine in mind. Installing higher horse power, heavier, water cooled, FADEC controlled engines In a Soex is plowing relatively new ground, all with their own problems.
In conclusion, I chose the Aerovee for all the good reasons. The only problems I have had were caused by me, made during assembly. Easily corrected. The Hobbs just turned 151.3 hours and I'm looking forward to hundreds more.

[gammaxy]

In conclusion, I chose the Aerovee for all the good reasons. The only problems I have had were caused by me, made during assembly. Easily corrected. The Hobbs just turned 151.3 hours and I'm looking forward to hundreds more.

In an earlier post you mention losing a cylinder due to a fouled plug. Do you feel like this was a problem you caused during assembly? What do you think the culprit was? I would expect that the big gaps (compared to other aviation engines) and the redundant ignition would make completely losing a cylinder due to fouling while in flight (at high power settings) to be pretty unlikely.

[radeluca]

Hello everyone, thank you so much for your help and info. I really appreciate it. I am feeling better about it.

[mike.smith]

The Aerovee is a proven engine, but, it must be assembled, adjusted, and maintained by you.
The advantages of the Aerovee are low initial cost, maintenance expenses, and overhaul cost. And, the Sonex line was designed with that engine in mind.

I agree. I have 220 hours on mine, and after the initial break-in of the engine and the AeroInjector, it's been pretty gas-and-go. I adjust the valves at least every 25 hours, get an oil sample report at every oil change (25 hours), and clean the air filter every now an then. In 3 years and 220 hours I haven't even yet had to replace a spark plug; just cleaned and gapped them. They've been in very good shape at each annual condition inspection. We'll see how they look this spring at the next inspection. I highly recommend getting oil analysis no matter what engine you have. If anything is going on in the engine, it will likely begin to show up as a trend in the reports.

When I had a prop strike a year ago I had the engine apart and cleaned in 2 evenings, and installed a new crank and bearings in 2 more evenings (doing that essentially means putting 90% of the engine back together again). If I had not been the builder of the engine the prop strike would have been a MUCH larger event. Incidentally the inside of the engine, including the crank and bearings, looked almost new. I replaced them from an abundance of caution, and because it would have taken too long and cost too much to send out the crank for inspection.

I've flown two trips to Oshkosh, totaling almost 4,000 miles with no mechanical issues. That was running the engine 10 hours a day.

My biggest "issue" with the VW is I can't seem to keep the right pushrod tubes from seeping oil. It amounts to maybe a teaspoon for every couple of hours of flight, so it's not enough to really even register on the dipstick, but it does register as drips on the pavement under my cowl. It's more of a nuisance than anything. I've tried several times to do all the things you're supposed to do to keep them from weeping, but so far I'm still trying. That's really a VW thing and not an AeroVee thing.

[radfordc]

In conclusion, I chose the Aerovee for all the good reasons. The only problems I have had were caused by me, made during assembly. Easily corrected. The Hobbs just turned 151.3 hours and I'm looking forward to hundreds more.

In an earlier post you mention losing a cylinder due to a fouled plug. Do you feel like this was a problem you caused during assembly? What do you think the culprit was? I would expect that the big gaps (compared to other aviation engines) and the redundant ignition would make completely losing a cylinder due to fouling while in flight (at high power settings) to be pretty unlikely.

I use to lose 4 spark plugs on every flight. That was due to shutting off the electronic ignition and running on only the mags. My engine ran cooler like that.

[Fastcapy]

I hated mine at first. Once I replaced the Aerocarb with the Rotec, changed the intake elbows to a different design, replaced all of the plug wires with high quality wires and some other small changes I now feel it is an OK motor.

I still find it just OK, because it seems like a never ending battle chasing down oil leaks (Sonex has said if it isn't leaking there isn't oil in it) which I don't really care for oil dripping on my exhaust pipes. I have rebuilt the top end twice, once was a goofy deal though that wasn't any fault of the Aerovee. It is a very needy motor, meaning you have to like to work on it, a lot. They say it is a motor for those who like to tinker and I think that is a bit of an understatement. The guy I bought my motor from actually had a motor and a half and it was good because I have used a lot of the spare parts that I had from him.

It is a pooch on warm/high DA days.I doubt you will see 80hp on takeoff as you are probably not going to turn that many RPMS, you will more likely see 70-74hp on a good day with low DA and a motor running well. However, the performance isn't any worse than a lot of other 2 place airplanes out there.

Pros: Low cost way to get flying. Good fuel consumption. Replacement parts are cheap through online VW parts houses. There are aftermarket parts available. Easy to rebuild. Core of the motor is pretty robust. Has a nice sound to it.

Cons: Oil leaks, fix one and another pops up. Always seem to be working on something on it. Low TBO, many people are getting maybe 500hrs before overhaul, although in fairness you could do an OH every 250hours for the rest of your life and still be under the cost of an OH on a lycoming or continental and they are easy to rebuild. A little under-powered as a 2 place powerplant. Wasn't at all satisfied with the Aerocarb. Some have good luck with them many don't. Be careful not to pull the threads out of the head with the spark plugs.

The best thing I ever did for my Aerovee was change the intake elbows to a smoother flow design and install the Rotec TBI. It almost seems like a different motor now.

However, had I had the funds to purchase a motor with more HP I would have. I don't feel like changing it now since my money and time is going into building a different plane so I will deal with it until I sell it when my next build is done.