MaJ. Woody

My Feedback: (28)

Hi Guys.
On my sixth Panther flight today I had a flame out. The Titan SE is bran new and has less than one hour on it. The GSU says power fail.....indicating that my RX batt was low. Well I check them before every flight and each pack was a 6.57V under load. After getting that message on the GSU I checked the batteries again and they were at 6.54V each. I fired up the titan and she ran great. No bubbles anywhere. I was stumped. Well I had a similar problem on one of my P-70's and it turned out to be a faulty RPM Sensor. When the ECU see's zero RPM it thinks it has lost power and shuts things down. I think that is how Bob Wilcox explained it to me. Anyway based on that experience I plugged the GSU back in and pressed the ignition switch several times. I was getting good rpm readouts so I am still stumped. I am worried to fly this plane again for fear of another flame out this time maybe in a bad spot that would cause me to ditch and trash my airplane. When I do fly it again I will keep it very high and limit myself to a racetrack pattern that can provide more options in the event of another flame out .
Any ideas??

MaJ. Woody

My Feedback: (28)

By the way my ECU battery was at 7.8V.

I was just reading about static electricity in the Jetcat Support forum. Funny thing was that the loose grass around the airport was stuck to my Jersey Modeler can. I could not wipe it off. I had to blow the grass off the fuel can. Do you thing I had a static electricity issue? My fuel can was almost empty if that mean anything.

Here is the post from the other forum I was reading:




Jetcat experts,

Can you tell me specifically what can cause a PowerFail Error message? Is it power loss from the receiver battery only? Or power loss from the ECU pack only? Or perhaps either can cause this message...

My Titan shut down during midflight. After "landing" the model, we attached the GSU to the ECU, and we could not read the output - the GSU character field was filled with very dim text boxes. After relocating the model, and doing a quick check on the ECU pack, we were able to read the PowerFail message.

Post-event, the receiver pack read 5.2v with a mild load, and ECU I believe was reading 7.5v with a very short duration 1.0A discharge. Tomorrow, I will discharge both packs (NiCd), but I am confident they will be of good capacity.

Thanks for any suggestions...


Update - I just got off the phone with Bob Wilcox, and he strongly suspects I've been bitten by the static electricity buildup issue, from the fuel lines. I'll eventually post later after I get some addtnl flights, to see if this can be confirmed.

_____________________________

-Ron S.

Wayne22

My Feedback: (2)

It may not be a faulty rpm sensor, but the sensor may be picking up something other the rpm signals. I have a very similar situation (different engine, differnt jet) and after exhaustive trouble shooting I found out that it was a noisy flap servo of all things!! It was causing some sort of interference which fooled the sensor into reading false and low RPM's so the ECU shut the turbine down. Easy to check- turn everything on, plug in the gdt and exercise every servo. Put a bit of load on the flight surfaces....if you see any RPM reading when the engine is stopped, you're getting some interference and will have to take steps to eliminate the cause.......


Have you flown the L-39 yet?

MaJ. Woody

My Feedback: (28)

Thanks Wayne.
Come to think of it I have a noisy flap servo myself. I also have an ocassional noisy steering servo. I will put the GSU in place and move the servos as you suggest. I have one flight on the L-39 and it flew great.

quist

My Feedback: (198)

I have 10 flights on my Titan SE and have had 2 of the same flame outs. I haven't had a chance to send the motor in yet.

At first I thought maybe it was a loose wire. It died on a very high speed high G pull. The second time was on a slow 1/4 throttle flyby 10' agl over the runway. that is a very bad place for a flame out.

acw

My Feedback: (1)

This is very interesting and easy to check. Thanks for sharing!

KC36330

IF you have a power surge on either of the electrical systems (the ECU or the RX batteries) you can get a power fail and flame out. I've had it happen because of a bad servo that caused an excessive amperage draw at a particular point in its travel pulling down the RX battery for a micro second and once when i had a future jet jock helping fuel everything up and he got sand in my smoke system (i didn't have a filter on it back then), a grain of sand got stuck in the smoke pump gears and locked it up, the power spike of that killed the turbine, the engine fired right back up and if the smoke pump hadn't been locked up I'd of never found the cause of that one.

so to sum it up, your batteries may well check in acceptable voltage range but a short power spike still could of caused the problem.

quist

My Feedback: (198)

I know battery condition was not a factor in mine. I wasn't in a position that I was pulling any amps, extended slow straight and level flight. I am also running dual a123 batteries, my only restriction is the two powerplugs going into the receiver. It also happened on the first flight of the day both times.

MaJ. Woody

My Feedback: (28)

Lots of good info coming my way. Thank you. I tried hooking up the GSU and moving the servos and even put some load on the servos as suggested but no RPM was displayed. Pushing the ignition button and watching the RPM readout produces some weird readings. For example if you push the button and run it up to say 3500 rpm and release it it will start to wind down. The numbers count down rather clunky meaning not very linear. Anyway, when the display gets to zero the turbine is still spinning a bit. Then after the turbine stops spinning the gsu goes from zero to like 700 rpm and then winds down to zero. I was concerned by this but I tested my Titan that is in my F-18 and it acted the exact same way. Next I tested both of my P-70's in my L-39 and A-4 and they did the same thing so it must be just the nature of the beast.

Gary Jefferson

My Feedback: (167)

Dom, I don't know what type of batteries you are using or if it would have any affect but you might want to check and see if the battery setting in the ECU matches the same type of battery and cell setting for the batteries you are using; i.e. Li-Po or NiCad and 6 cell, 8 cell, etc.

Also, you can watch the GSU on startup to see the voltage. If there is a substantial drop or problem with the batteries you may see it on startup because of the high battery loads on startup.

MaJ. Woody

My Feedback: (28)

Hi Gary.
Thanks for the response.
I just checked the battery setting and it is set for Nicd 7.2V. I am using the supplied 7.2V Nimh 3800 Mah pack so this is correct (the only other setting is for Lipo's). Interesting, I checked the statistic menu and there is a display for low battery cut outs and the value displayed is zero. Should this not say 1 since I was given a power fail error? Or is this like failsafe counts where it resets itself after you cycle the power?

Gary Jefferson

My Feedback: (167)

Dominick, it probably resets itself, not really sure.

In the manual it says that power fail can be caused by an ECU or receiver battery that was disconnected or intermittent or if the receiver pack goes lower than 3 volts. Maybe you can check for loose ECU power cables, solder joints, etc.


Are you running a 2.4 Ghz system? Did you check the fail safe count in the GSU?

Ron S

My Feedback: (2)

Please pass the cause down to us if you figure out your Powerfail. I've had this happen twice to me out of about 8-9 flights, with both times adding minor damage to the airplane. After the first occasion, I added the conductive fluid to the fuel. I had 3 successful flights, then on the 4th flight (at top gun of course) it Powerfailed again. I've never noticed any hint of static charge buildup during fueling - of which some of you have seen.

I alway top off my batts (all NiCd) before every flight. Most of my flight control and big drain items are on a dual 6v pack seperate from from the rx, ecu, and retract/brake servos run off of a separate 4.8 pack. And on every flight I will lose approx 130-150 mAh on the 4.8 pack.

So far, I've banged on the packs while attached to a voltmeter to look for suspect welds/solder joints. I now have the turbine installed on a test stand, and will disconnect wires so I can find out for sure what can and cannot cause a Powerfail.

I'm not saying it is a turbine issue necessarily - but this is my 3rd Jetcat, and 5th turbine in about 5-6 years.

Edit - thanks for the suggestion regarding adding a load while testing - I'll try that out on my test stand. Good suggestion!

KC36330

a power fail results in the ECU not recording the last run, all information in the ECU will be from the previous run.

Miquel

I had the same problem, the probem is the conector of trotle or aux your can check it Start the turbine and when is runig o touch the conector (ECU) and your can see whit GSU the saim fail.

pilott28

My Feedback: (27)

I had this problem once a while back, and we never did find the cause. There could be a lot of transient reasons and unless it repeats itself, you may never get a definitive answer.

I reported the problem to the manufacturer, and they eventually built a small fail safe time delay into the system, so that if it were truly a transient event, the engine wouldn't quit. You might check with Bob W. to see if there is a way to set this into the existing JetCat ECU.

I'm not sure why this isn't set up as a standard feature, much like loss of signal from the receiver. There is probably a reason .. maybe Mr. Matt could shed some light on the engineering aspects of this problem.

i3dm

My Feedback: (51)

A friend of mine bought a new P70 that flamed out on the first flight (ground test was fine).

When we plugged the GSU we got a flat (blank) screen and GREEN \ RED lights steady on. reset the system, says POWERFAIL on the last run, and all works fine.
did this again a couple flights later, talked to jetcat in Germany, they said to send it back, he did and got a new one by warrenty, they said it was a bad turbine. i do not know the exact reason for the failure. all batteries were fine (load tested) before and after the flame outs.

AndyAndrews

Why don't we have dual batteries for the ECU/Pump like most of us do on the RX's? Weight? Has anyone done this before?

KC36330

IMO it just isn't necessary. the only major current request from the battery is during start and it's not often at all that you'll ever get enough of a current drain in flight for the ECU battery to drop out, if you are getting unexpected low battery cut offs you should charge more often or replace the battery. with the exception of the smoke pump additions often tied in with the ECU battery the only thing on it is the ECU which if it has a fault causing an excessive current draw (turibine is gonna shut down regardless) or the fuel pump is jambed (no fuel, no flame) and dual batteries ain't gonna solve the issue.

lugebob

I used to be plagued by Powerfail Conditions. Of course my craft sees a bit more shock type G's on the road, but it took me for ever to find that I actually had a loose factory crimp connection on one of the JR type leads. Everything would run fine until something got bumped a certain way. I troubleshot with a o'scope probe on the Pulse wire (Throttle) to the ECU and went all over everything tapping, banging and moving wires until I saw the pulse train glitch on the scope. It was still illusive to find the exact wire, but I did not have to RUN to isolate the culprit. I just starting replacing wires in the circuit with new connectors until it stopped.

good luck

Kevin_W

My Feedback: (1)

Several years ago I was helping a guy with his F-22. It would run fine until we started to taxi it out to the runway, then quit at almost the exact same location. The reason was always "power fail".
After the third or fourth time I noticed that the shutdown coincided with him wiggling the elevators during the taxi.
The system was fine until the elevator servos (the largest servos in the plane) were commanded to move. When they did the load on the receiver battery went too high and the ECU sensed low voltage and shut down.
He said he couldn't understand why it would do that because he had used redundant battery packs.
When I checked out his install I quickly found the problem. He had used the little standard Futaba switch (with 22 gauge wire), and his "redundant packs" were both Futaba packs (with 22 gauge wire) and he had long extensions (22 gauge wire) between the packs and the switch.
I loaned him the receiver pack out of my airplane, and we bypassed the switch by plugging it directly into the reveiver. That solved the problem.

He was lucky that it happened on the ground.


The point of this is that it could be any number of things.

It could be due to a bad cell in the battery, a loose connection (which could be anywhere between the battery and any of the servos or ECU), a bad switch, improper wiring, or possibly even a servo that is going bad.

I would first visually inspect all wiring connectors and switches.
While running the engine and apply a load to several of the servos (simulating flight loads),then wiggle wires and tap on switches and connectors at the same time. Try loading the servos in different directions and wiggling the controls around while loaded.
It shouldn't take too long to isolate the problem.

MaJ. Woody

My Feedback: (28)

Just checked all the connections to the ECU again. All seem fine including the solder joints on the power cable. The throttle connection while tight between the servo connector and prongs has more side to side wiggle than the rest. I must assume the whole assembly is moving a bit inside. I wanted to check but there is a tamper seal on the ECU and I don't want to void my warranty.

Vincent

My Feedback: (61)

I had a problem a couple of years ago with my Titan where it would not start at the field. I plugged in the gsu and discovered there was zero rpm on the startup sequence. I unplugged the black telecom wire from the motor and reseated it. The system would come back up ok and work for that flying session.After having this happen a few times i ended up replacing the telecom wire and never had a problem since.
Good info on this thread.
V..

Kevin_W

My Feedback: (1)

If you suspect the ECU has a problem send it in and have Bob Wilcox take a look at it.
But,
As I tried to explain in the other post, the problem could be anywhere in the electrical system.
A poor connection or a bad component almost anywhere in the electrical system can create a high amperage load that will cause the ECU to sense low voltage. The high load condition could be very brief (bad spot on a servo pot, control surface binding at certain deflections, wire or connector that creates a short under certain g-loads). The battery voltage will drop while the high load condition exists, but will return to normal as soon as conditions change. This will make it fairly frustrating at first, but if you systematically go through it as I suggested above you should be able to find the cause.

MaJ. Woody

My Feedback: (28)

What would you consider high amperage? I am running two 6V packs to the RX that can each deliver 40 amps. I have a couple servos that buzz a bit but when I put them on my Hanger 9 meter it only shows very little current draw while buzzing.