Aeroinjector -- caution!

[Fastcapy]

I have a slightly used Rotec on my desk (paper weight) that I wouldn't sell to my worst enemy.

Just as I have both an Aeroinjector and Aerocarb I won't sell because of all the problems I had with them and the factory's stubbornness to fix known issues with them, like the issue described in this thread.

FWIW, I have had no issues with my Rotec in 125hrs, and they have been helpful when I have contacted them about setting it up etc. With my Rotec I actually feel comfortable with my motor now and take it on 350mi cross countries to see my son at college on a regular basis. With my Aerocrab I never flew further than my friends could drive a trailer in couple of hours to pick me up because I had no faith in that carb after non stop issues with 2 of them.

[floridasonex]

I think the design should be such that you don't have to
Peen the threads or put ball bearings in it.

RT

[sonex1374]

Roger,

Most AeroInjectors do not have the overly-loose fit that you described in your needle carrier, and thus do not have the same issue you had with yours. Was this due to wear over time, or loose tolerances from the beginning.... I'm not in a position to answer that. However, other users might experience something similar, so it's important that we share our problems and solutions freely. My point about peening the threads was simply to offer a way to restore the "drag" on the needle carrier to prevent unwanted movement. Galling will be an issue if you overdue it, though. Another solution would be to order a replacement carrier that was not worn excessively.

I'm intrigued by your suggested modification to the carb to prevent the carrier from moving to an overly-lean position. That may warrant further consideration. Over time these things have a way of getting incorporated into the design, and that's good for all of us.

This is another situation where as the pilot in command and chief mechanic of our planes we have to remain tuned-in to indicators of problems, and if we have a suspicion that things are not right, we need to follow up and find out why. Sharing these negative experiences is vital to improving the breed and increasing safety across the fleet. Thank you for doing so!

Jeff

[floridasonex]

"just as I have both an Aeroinjector and Aerocarb I won't sell because of all the problems I had with them and the factory's stubbornness to fix known issues with them, like the issue described in this thread."

Honestly ... this whole thing makes me mad as hell. Not only because of the major loss of power that could have left me in a pile in the swamp but because I chased my tail on temperatures for several weeks not knowing when I made adjustments to the needle the set screw was continuously pushing it back even more lean. If I was the manufacturer of a product that had a failure that could result in someone being killed I would be on the phone immediately to discuss it .. . Not simply send them an email to pound down the threads.
I finished and started flying this Sonex 5 years ago. Prior to that I owned a Sonex that I didn't build. So I'm not new to the Sonex/Aerovee. Before that I built and flew for a few years a Titan Tornado S with a Jab 2200. I had no issues with it. This isn't a case of it not being setup right. It's a case of a potentially fatal manufacturing defect. I'm sure I can come up with a solution to keep this from happening. That would probably take the form of a pin or screw in the slider to keep the carrier from moving lean. First I'm going to explore other carb options. I'm not sure I'm comfortable continuing to use the Aeroinjector.

RT

[Sonex1517]

Well stated.

I am also one who chased a problem with my AeroInjector that was the result of a loose locking screw. Peening the threads solved the issue.

I also find it irresponsible for a manufacturer to be aware of a problem like this and totally ignore it. I am certain we will be told this has never been reported before, and this is the first that the have heard of it. Just as I find it irresponsible to continue selling a turbo that has never been tested properly and has a “solution” that the manufacturer admits has not been tested.

[kmacht]

The problem with peening the threads is that it is only a temporary solution. It restores the drag only until the stainless screw wears the soft aluminum housing threads away again. It doesn’t take many adjustments until everything is loose again. This has been an issue since at least 2009 when I sent the factory tech support a question on what to do about it. Their solution was to hit it with a hammer. If you search this forum or the old yahoo archives you will find that you aren’t the only one that has had this issue. You are the first that I have heard of it causing issues in flight.

Keith
#554

[lutorm]

I added a very small O-ring between the adjustment screw and needle carrier. The intent was to get rid of the play where the carrier is held in the screw, but it also had the unintentional side effect of acting as a "thread locker" of sorts since the friction against the O-ring prevents the screw from turning freely. I don't think it would move under vibration even if the set screw came loose.

[builderflyer]

Once you have the needle adjusted close to where you want it turn it in a couple of turns and add a drop of blue loctite. Then back the needle up those same couple of turns to engage the loctite. Let the loctite set up before installing the set screw. If you have to make small needle adjustments in the future you can do that and the residual loctite keeps the needle from moving while you engage the set screw once again. Been doing the above for years with success.

Art,,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,,,Jabiru 3300 #261

[lpaaruule]

I have a first generation Rotec TBI that I had installed on my Jabiru 3300, but ended up replacing it with an AeroInjector before I ever started the engine due to hearing what happened to John Gillis, and a couple RV owners. A friend of mine flew with a Rotec TBI for a couple years until it's seals started leaking, and causing the engine to run too rich. Before I switched to the AeroInjector, I bought the new regulator diaphram, and needle design, but never installed it.

My AeroInjector's adjustment screw turned freely when I first got it. I was surprised to hear Kerry say in the Sonex Flight podcast that it has been standard practice for Sonex to peen the threads now for years, as mine wasn't peened. Having said that, I knew (thanks to this forum) that this could be an issue and peened the threads myself right from the start. Unfortunately I was overzealous in the peening, and could barely turn the screw back in, and had metal flakes falling in the needle channel. After cleaning the AeroInjector and working the screw, it's now snug, but working well.

The other issue I had with the AeroInjector was it sticking at idle, even without the engine running. At first I thought it was my cable routing, but it ended up being the slide sticking on the back side. I disassembled the AeroInjector, and applied a very light dusting of graphite, and blew it out so there would be barely any graphite left in on the slide. My AeroInjector has worked very smoothly from then on.

So far, I have about 32 hours on the plane, and I've been very happy with the AeroInjectors performance. The adjustment screw it tight enough that I'll be surprised (literally) if it loosens before I readjust it for winter flying. If it's easy to turn, I'll peen it again. In the mean time, hopefully someone will come up with another solution.

As for the Rotec TBI, the engines that quit that I know of were all using the second generation version. Like I said previously, Rotec MIGHT have solved the problem with the new needle, and diaphram, but I decided that I didn't want to be the one to find out. Having said that, I'd sell the Rotec TBI to someone at half price as long as they are fully aware of the reasons that I decided not to use it.

[Sonerai13]

I have heard that, if you take a small piece of stainless steel, cut to the square shape of the needle carrier, and insert this between the needle carrier screw and the set screw, it will prevent both the creep of the needle while tightening the set screw, and the loosening of the set screw once tightened down. I have not tried it personally, but plan to at some point in the near future. Will report back.