Video from my engine failure & emergency landing on 6/29/18

[kmacht]

And the factory still maintains there isn't a problem, the burps are normal and not to worry about it.....

[Msing48]

The engine stoppage that I had was on a first test flight of a friend's Sonex. The mixture screw had quickly repostioned itself. However, it was not because of a loose set screw. It was because the set screw had never been installed.

On my Sonex I exchanded the original Aerocarb (sticking slide) with the AeroInjector and never had another carb issue as long as I had the Aerovee engine. I had no problems with the set screw turning the mixture screw on either carb. When I replaced the Aerovee after 9 years with a Jabiru 3300, the new AeroInjector did have a problem with the set screw turning the mixture screw. I slightly deformed the square brass piece where it held the needle ball and had no problem.

I actually like the Aeroinjector a lot. Except for the sticking slide issues with the early AeroCarb, the AeroInjectors have served me well for the 12+ years using them on both engines. I understand the complaints that some of you have but maybe I am of a somewhat different mindset than some of you. I accepted the fact that I built an experimental aircraft and that it was totally my responsibility to make it safe no matter what or who's parts/components I choose to use. Would I prefer that everything I purchased was perfect? Sure, just as I wish every part I made for this plansbuilt aircraft was perfect. I think there are a LOT more Sonex owners that have none of these set screw problems than there are those that have the problems. Phase one testing is designed to weed out these problems and should be done in areas providing adequate emergency landing spots.

Maybe I sound like a factory rep but I assure you I am not.

[SonexFactoryTech]

And the factory still maintains there isn't a problem, the burps are normal and not to worry about it.....

Sonex Aircraft maintains that there is cause to every problem but there is no single cause to every problem. We encourage Tom to contact us directly for one-on-one support on his engine/fuel delivery issue, which may be caused by more factors than the list has suggested. As a second-hand owner, Tom may not know if his fuel system is correctly installed. He may not know if his AeroInjector was properly tuned. He may not know that someone sloshed his fuel tank and the sloshing compound is plugging his fuel filter. He may not know a mud dauber has made a home in his fuel vent.

Sonex Aircraft prefers not to charge forward with knee-jerk assessments like some vocal members of this group that take every opportunity to assail the AeroCarb/AeroInjector. However, in our opinion, we hear surging indicative of fuel starvation (for whatever reason) and not an intermittent miss caused by vapor in the fuel line.

Sonex Aircraft, LLC

[mike.smith]

That doesn't sound even remotely like a "burp" issue. Totally different IMHO. I would offer 2 things to look at:
1. Obviously the entire fuel system from tank pickup, to vent, to injector needle.
2. I had a similar thing happen (but not surging; just a pronounced power drop). I have a bracket on the engine the holds the mixture and throttle cables at a continuous and smooth arc from the firewall to the AeroInjector. After an oil change I forgot to tighten the bracket and that let the entire mixture cable housing move, rather than the housing staying in place and only the cable inside moving. I landed, tightened the bracket and have had no issue in the 3 years since that happened.

And excellent job keeping your cool and flying the airplane!!

[Titanium Cranium]

As the second owner of my plane, and with the original owner/builder having passed away before I purchased the plane, I've had to learn things about my plane and the Sonex design in general through experience and, luckily, though here. Kerry at Sonex tech support has been very helpful with answering the questions I've had, and while I haven't spoken to Sonex about this yet, I'm sure they'll be very helpful. I definitely understand the controversy over the whole "known issue" thing, but I also know that we can have two identical planes and have one produce a problem that the other doesn't. That's the nature of mechanical things, especially experimental. That's something I accept and I won't hold that against anyone on either side of the debate. For me, I'm not really concerned with the debate. I just appreciate the feedback you all have provided in helping me figure out what's wrong with my plane. Based on what I've been reading about the burp issue, it does sound like that may very well be what I have, but on a more continual vapor lock basis. I've had the burp on my plane in the past, although I didn't know that the very brief stumble I occasionally felt on my take off roll was known as a burp, or that it was a momentary vapor lock. I knew that it only happened if my plane had already been running and was hot, and I just figured that it was sensitive to how fast I applied full throttle. I aborted the first takeoff where I felt it, but when I tried it again, I applied full throttle slowly and smoothly, and I didn't feel it. I would only feel it if everything was hot and if I pushed the throttle too quickly. I know some planes are sensitive to that, so I just figured mine was too. On Thursday evening before my emergency landing, I did feel just a few stumbles on my 3rd leg of the day while cruising at 4500 ft, but when I adjusted my mixture slightly richer, it went away, but the engine and everything in the cowling was very hot from having flown almost 7 hours that day. On Friday, my first 2 legs went without incident, but also brought us from Oklahoma into New Mexico, where it was a hotter environment than I'd ever flown my plane in, and the density altitude was far higher than anything I'd ever done with it. The engine and cowling was very hot when we landed at KTCC, and we had just experienced about 2 1/2 hours of rough turbulence, so we parked the plane for a little over 2 hours and went to get some lunch. I figured that would cool things off a lot, but the plane was also sitting in the sun with the outside temperatures being 102 degrees. It was in the sunlight with it shining on my black glare shield the whole time. That definitely kept things hot during the break, and it only cooled off to 100 degrees outside by the time we departed. Everything was normal when we got in and started up. I did find that I had to give it slightly more throttle at that airport than normal (both after landing and before takeoff) but I figured that was normal considering the field elevation was about 4000 ft and the density altitude was 7800 when we landed and 7400 when we took off. I did a longer run-up than normal to check everything, mainly because I was flying into an area that was higher terrain, had very few airports, and I wanted to make sure I had leaned my mixture for the best performance possible with a 7400 ft density altitude. The plane performed better than I expected and was climbing nicely at about 200 ft/min at gross weight and at about 75 mph. All numbers looked great with my EGT being about 1200, my CHTs all being below 375, oil temp staying around 200, and with oil pressure being about 30. These numbers held pretty constant until shortly after we climbed through 6000 ft, which is when the engine stumbled a few times. I made the mixture richer as I had the evening before, but with no improvement, and leaning also had not smoothed the engine out. That's when I turned toward I-40 and started trying to make additional adjustments. Pulling back the throttle a bit didn't seem to help, and adding full throttle didn't either. That's when I got ATC on the radio to report engine troubles. As I descended, the engine started to stumble even more and became notably worse, which is when I declared the emergency to ATC. After pulling the plane off the runway in the crazy winds and making a couple phone calls, I was exhausted, so I decided to see if the engine would start again, and it did, just as it had prior to takeoff. I was able to taxi under power to a hangar near the FBO and shut it down without any issue. Based on my knowledge of vapor lock (admittedly not a vast knowledge by any means) and based on the understanding of the brief stumbles I experienced numerous times before, it sure seems like the common burp was turning into a full-blown vapor lock condition. I do plan on pulling the Aerocarb apart to clean it, and I may go ahead and bypass the gascolater so I can fly it home, then install the burp line setup. I'd like to install the burp line before flying it back, but I'm sure I'll end up running into some fittings that I'll need, and the nearest hardware store would be at least 200 miles away. I definitely want to do a good amount of ground runs under power for at least 15 minutes, and do a solid hour of flying around the field before I'd be comfortable flying it home, but I think that it'll be good if I focus on pulling the cowling for a bit to let things cool down longer at fuel stops.

[WesRagle]

I definitely want to do a good amount of ground runs under power for at least 15 minutes

Hi Tom,

You might want to check page 61 of the current revision of the AeroVee assembly manual before performing extended high power ground runs. The manual is available here "https://www.sonexaircraft.com/manuals/".

Best of Luck and Take Care

[Titanium Cranium]

Thanks for the info Wes. I'll call Sonex tech support to find out what they think is a safe ground run time. I don't know if engine time plays a role in what is considered a safe ground run time, as I see the warning for ground runs is listed in the break-in/first start up section of the manual, and mine has about 160 hours on it.

[DCASonex]

If you want to do extended ground runs at high power settings,with any air cooled aircraft engine, take a look at the extensive cooling shrouds and blowers used for dyno testing to take the place of strong ram air effect of actual flying. If you cannot duplicate that, don't run the engine for long. Hot spots can quickly develop especially on steel cylinders that do not conduct heat as well as aluminum causing oil to break down and rings to scuff or score the bores.

David A.

[Titanium Cranium]

Just wanted to give you all an update. I got back out to New Mexico to fix my Waiex and fly it back home to Ohio. I did a double layer of fuel line heat shielding and wrapped the exhaust to minimize heat transfer. That did the trick. The test flight went perfectly, so I started the flight home. With the time it took to check things over, make the repairs, and then wait out a dust storm, I only made it to Amarillo before sunset. The next day I completed 4 legs between Amarillo and Dayton (of course I managed to pick a day with a headwind blowing out of the East). As a precaution, because I couldn't install the "burp line" prior to flying home, I pulled my cowling for an hour after the second leg to ensure that things cooled off well. I didn't have a single "burp" or issue at all on the flight home, aside from some ridiculous turbulence between Missouri and Illinois. Now that I have her home and my own tools at my disposal, I'll install a burp line and make a heat shield for the gascolator. I also plan to wrap only the right side exhaust at first so I can take temperature measurements to see what kind of difference I actually get between a wrapped and unwrapped exhaust. I'll wrap both in the end, but I'd like to see what kind of difference it makes. I'll let you all know what the results are of that, but it looks like all I needed to do was find some ways to prevent the vapor lock.