I have a low time Behotec 180 that flamed out twice in flight at the Route 66 jet rally this past weekend and I am at a loss to explain why it happened. Both times the flameouts occurred right at 4 minutes into the flight at the same steady throttle setting with no noticeable thing amiss during the flight up to that point. Can the timing of when the flameouts occurred just be coincidence?

The first thing one suspects and the first we eliminated is the fuel system. No sign of air bubbles in the fuel line, the filter or anywhere else except the UAT and that volume of air was pretty small; about what you would expect from a normal flight. We pulled the tank and checked the clunk and that was in good shape as well.

There is one thing different from the previous flights where the engine performed normally. I sent the transmitter in for service because the speaker had completely quit working. I was told by EspritRC that they replaced the main board in the transmitter, (Jeti DS-16), tested it to make sure all was good and returned it to me shortly before the rally. The engine started normally, just like always, so I didn’t suspect there was any effect from the service work that might have caused the flameouts. I have yet to redo the stick setup on the ECU but that will happen before I do ground testing. Since the engine started normally and ran fine for 4 minutes I really don’t suspect that redoing the ECU/stick learning process will solve the issue.

Of course, I discussed the flameouts with various other pilots at the rally. One asked what battery I was using to power the ECU. The battery is an HRB 3s 4000mah 100C battery. They said the voltage was too high and was heating up the ECU. This evening I charged the battery and it was at 12.5 volts coming off the charger. A manual for the type ECU the engine uses says power should be 12 volts maximum. The battery was freshly charged prior to the first flameout flight. That extra .5 volt doesn’t seem to be enough to create issues?

Fuel doesn’t seem to be an issue because the same fuel, Jet A with 5% Kingtech oil, was used in another smaller engine for many flights at the rally with no issues.

Anyone have similar experience with this engine?

Unknown or unknowable causes are the worst!!

See if you can reproduce the problem on the ground.


Do a “flight on the ground” and see if it is reproducible.

You should NOT "assume" things.....

I have one Behotec engine and have not used it much, but the start sequence is different than other Turbines I have. I will note that the KingTech engines require a three cell LiFe battery for the ECU, while maintaining that a "start" sequence must not be initiated with an ECU voltage over 10.0 volts and they are NOT lying.

This prohibition is not due to some issue with the ECU, or the engine electronics, but the starter glow plug will NOT take over 10.0 volts without burning out.

Please be aware that Turbine engine settings, unlike their glow counter parts, ARE NOT APPROXIMATE!

Start over with a fresh setup on a different model memory with the required settings and see how things go......

Hi Steve,
Had a 'ramp up' board fail in my Behotec (didn't know that something like that could exist!). Symptoms were as you describe - everything normal right up to the point of failure in flight with no white smoke. May not be that but worth a check - had to send it in though for it to be discovered.
Bob

As I read the original post describing the problem, I had just experienced this very same type of issue and thought I how ironic to see this.
I did all of the very same troubleshooting to search for my problem. Long story short, My motor was a Jet Munts 200 and my issues started in a very same manner. I had never had a flame out since owning the motor over several yrs of use. Mine flamed out about 5 minutes into my flights with no visual signs. I inspected fuel system and checked all my cables after first flame out, even tried a different battery. After second flame out on my next day out to the field, It turned out that I found a loose screw mounting the motor's front circuit board. Tightened the screw and checked all wire soldered points on board. I didn't change anything else. Took plane back out to the field this past Saturday and got my flawless running motor back again. 3 great flights.
I know this may sound strange to some, but this is my personal experience over the past couple weeks. May be worth looking at and good luck with your troubleshooting.

I absolutely will be doing ground testing to try and reproduce the flameout and make adjustments before it flies again.

I had a similar experience with my Boomerang XL, the engine stopped after 4-5 min after TO, I have it on video, end up been clear algae plugging the fuel filter, clean it and the symptoms went away.

I just read a similar post about a Behotec on FB. Turns out the electronic board was faulty and Behotec fixed under warranty.
Jeti Duplex Owner's Group (Sept 10th)

You could try calling Woody at Ultimate Jets, they are the USA Behotec folks;

https://www.ultimate-jets.net/

Maybe the vent has limited air flow, ones I have bad valve with similar problems the electromagnet was weak and the fuel has been restored until closing the fuel flow