flame out
11-25-2002, 06:21 PM
#1
flame out
I have had 2 mysterious flame outs on the last 2 outings. After each one the GSU says low RPM and it was a low rpm of 26000. I have a P120. 4.0 ecu but old exposed rpm sensor. After each flameout I checked and there were no bubbles and filter was clean. The flameouts occured after a vertical snap and one occured after a tailslide when the engine was at idle. Never in forward flight with power. Idle set at 34000. I immediately ran the engine after coming in and would run to full power then back to idle. The rpm would dip to about 31 or 32, but at 50% power and then back to idle it would dip below 30. Would the min. rpm be too low or spool down time too quick? Or something else?
Also, how does the ECU know how many cells the receiver is?
Scott Marr
Also, how does the ECU know how many cells the receiver is?
Scott Marr
11-25-2002, 10:50 PM
#2
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flame out
I had some problems with a low rpm on me P-80, this is what I did to fix the problem. First I check the alignment of the rpm sensor and added shroud on the sensor and re-check the fuel tanks. This corrected the problem. Kelly
11-26-2002, 07:53 PM
#3
HI Scott
Sorry for the delay in response, I wanted to check one thing with Bob Wilcox and he is on a much needed vacation.
First, as to the flame out. Did you see any white smoke coming out of the plane? I can tell you more about this after I know that.
It is unlikely that the LEDs are the issue with a V4.0 ECU. This version of ECU has a software based "sanity check" that is continually performed on the incoming LED data, and will revert to an open loop mode if the RPM data is corrupted.
If you saw smoke it is a flame out (induced by an air bubble). I would check to see that your kerosene filter is mounted vertically, and thump it a couple of times with your finger to make sure no air is trapped in it. Otherwise start looking for sources of leaks on the suction side of the fuel system
The ECU battery cell selection is not a normal user changeable item.
Good luck,
First, as to the flame out. Did you see any white smoke coming out of the plane? I can tell you more about this after I know that.
It is unlikely that the LEDs are the issue with a V4.0 ECU. This version of ECU has a software based "sanity check" that is continually performed on the incoming LED data, and will revert to an open loop mode if the RPM data is corrupted.
If you saw smoke it is a flame out (induced by an air bubble). I would check to see that your kerosene filter is mounted vertically, and thump it a couple of times with your finger to make sure no air is trapped in it. Otherwise start looking for sources of leaks on the suction side of the fuel system
The ECU battery cell selection is not a normal user changeable item.
Good luck,
11-26-2002, 08:35 PM
#4
NO SMOKING
Hi Matt,
There was no smoke. IE no bubbles or air in system either time.
I havent upgraded to the new rpm thingamajig. I have heard of some flameouts with the one I have.
The question about batterys was posed to the receiver not the ecu pack. I had another flameout that said power failure. My receiver battery got down to 6v and ECU shutdown turbine. My low battery warning was disabled, so it just shut it down. I tried to find, in the programming, where the input was for 4.8 or 6.0 volts and couldn't find it. I figured the ECU must pick up the cell value automatically.
Scott
There was no smoke. IE no bubbles or air in system either time.
I havent upgraded to the new rpm thingamajig. I have heard of some flameouts with the one I have.
The question about batterys was posed to the receiver not the ecu pack. I had another flameout that said power failure. My receiver battery got down to 6v and ECU shutdown turbine. My low battery warning was disabled, so it just shut it down. I tried to find, in the programming, where the input was for 4.8 or 6.0 volts and couldn't find it. I figured the ECU must pick up the cell value automatically.
Scott
11-26-2002, 09:22 PM
#5
Hi Scott
As for battery conditions and shutdowns, there are 2 types
1.) As for the battery failsafe, that only applies to the ECU ( AKA pump or turbine ) battery. If you disable battery failsafe, then upon cell voltage <1.0V, the turbine will shutdown (no smoke) and the off condition will be shown as "BatteryLow".
2.) The "power fail" condition is fairly new, and is driven by the lowest RX battery input the ECU can take before the CPU browns out. Not sure what is is set at, probably somewhere around 3 volts, irrespective of the RX cell count you are using. That is usually caused by a bad switch, or your battery is really really low! THis has nothing to do with number 1, above. So chances are your battery was very bad, you had a momentary load that took it below 3 V or something to that effect.
As for the other flameout:
It is not beyond the realm of possibility that the LED sensor problem is at play here, but very unlikely. Let's pursue other avenues first.
Do you happen to remember the commanded pump voltage on any of these shutdowns? This is not the max voltage, but instead the pump voltage at shutdown.
1.) As for the battery failsafe, that only applies to the ECU ( AKA pump or turbine ) battery. If you disable battery failsafe, then upon cell voltage <1.0V, the turbine will shutdown (no smoke) and the off condition will be shown as "BatteryLow".
2.) The "power fail" condition is fairly new, and is driven by the lowest RX battery input the ECU can take before the CPU browns out. Not sure what is is set at, probably somewhere around 3 volts, irrespective of the RX cell count you are using. That is usually caused by a bad switch, or your battery is really really low! THis has nothing to do with number 1, above. So chances are your battery was very bad, you had a momentary load that took it below 3 V or something to that effect.
As for the other flameout:
It is not beyond the realm of possibility that the LED sensor problem is at play here, but very unlikely. Let's pursue other avenues first.
Do you happen to remember the commanded pump voltage on any of these shutdowns? This is not the max voltage, but instead the pump voltage at shutdown.
11-26-2002, 10:56 PM
#7
battery
Matt,
After the power fail flameout, I checked the RX battery and it read 5.80 on a load. I was in a four point roll on the knife edge at full power when it flamed out. I doubt battery could get to 3v. The battery is a 3000ma 6.0volt. This was about the 7th flight of the day without recharging. I am using a voltage regulator. There isnt a low battery limit that would shut turbine down if it got below say 5.5 volts? I really cant see it getting to 3v as the battery is fine.
Thanks
Scott
After the power fail flameout, I checked the RX battery and it read 5.80 on a load. I was in a four point roll on the knife edge at full power when it flamed out. I doubt battery could get to 3v. The battery is a 3000ma 6.0volt. This was about the 7th flight of the day without recharging. I am using a voltage regulator. There isnt a low battery limit that would shut turbine down if it got below say 5.5 volts? I really cant see it getting to 3v as the battery is fine.
Thanks
Scott
11-27-2002, 12:19 AM
#9
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flame out
Scott....
Just thought I would chime in on this one sice I had my first flame out with a Jetcat at FIJR. I had the same error on shutdown (low rpm) at around 26000 rpm. Culprit was an air bubble trapped in the filter. a few flicks of the filter at full throttle sent some very big bubbles out of the system. Would advise checking this first...
Good luck...
Todd
Just thought I would chime in on this one sice I had my first flame out with a Jetcat at FIJR. I had the same error on shutdown (low rpm) at around 26000 rpm. Culprit was an air bubble trapped in the filter. a few flicks of the filter at full throttle sent some very big bubbles out of the system. Would advise checking this first...
Good luck...
Todd
11-27-2002, 12:48 AM
#10
air
Todd,
Thanks for the input, but I have checked every possible air variable. Definitely not air related. I have checked filter, thumped it, opened it, everything. UAT looks fine, etc. There is never any air apparent in lines anywhere.
I have just remembered that the first flight I had on this motor it flamed out in Lubbock. It also showed low rpm 26,000. John Redman went through it and recalibrated egt and a few other things i cant really recall. This was my first Jetcat so it looked foreign to me then. After he did that I had another 75 perfect flights. But a few weeks ago I went to start and temp probe said 4 degrees, so we recalibrated EGT and then it showed a blown plug. Replaced that plug, then 5 minutes into flight it flamed out. I refueled and flew the rest of day with no problems. This past weekend on the 2nd or 3rd flight it did same thing. Both days were very sunny and about 60 degrees.
I have tried running it to reinact flameout, but cant make it.
Im still kinda wondering about spool down time. It dipping below min RPM after power to idle seems a little suspect. Seems like it should settle at 34,000, never going below 34K. Watcha think?
Thanks again,
Scott
I'll check the brand of regulator.
Thanks for the input, but I have checked every possible air variable. Definitely not air related. I have checked filter, thumped it, opened it, everything. UAT looks fine, etc. There is never any air apparent in lines anywhere.
I have just remembered that the first flight I had on this motor it flamed out in Lubbock. It also showed low rpm 26,000. John Redman went through it and recalibrated egt and a few other things i cant really recall. This was my first Jetcat so it looked foreign to me then. After he did that I had another 75 perfect flights. But a few weeks ago I went to start and temp probe said 4 degrees, so we recalibrated EGT and then it showed a blown plug. Replaced that plug, then 5 minutes into flight it flamed out. I refueled and flew the rest of day with no problems. This past weekend on the 2nd or 3rd flight it did same thing. Both days were very sunny and about 60 degrees.
I have tried running it to reinact flameout, but cant make it.
Im still kinda wondering about spool down time. It dipping below min RPM after power to idle seems a little suspect. Seems like it should settle at 34,000, never going below 34K. Watcha think?
Thanks again,
Scott
I'll check the brand of regulator.
11-27-2002, 12:53 AM
#11
Hi Scott
THe low RPM has to be 10% below spec for at least 3 seconds, so a quick low RPM excursion will not do it. It will go below the low RPM, if it did not the spool down times would have to be much longer (so called "underdamped" controller settings)
Another possibility is a restriction in the fuel system, not just air bubbles. That is what I want to talk to Wilcox about. It has to do with a restrictive fuel system and how that affects reponse at idle.
I understand that your filters were clean, but it can also be cause by a pinched line, or a clogged cluck or UAT.
I am trying to respect his vacation, but I will contact him tomorrow.
Another possibility is a restriction in the fuel system, not just air bubbles. That is what I want to talk to Wilcox about. It has to do with a restrictive fuel system and how that affects reponse at idle.
I understand that your filters were clean, but it can also be cause by a pinched line, or a clogged cluck or UAT.
I am trying to respect his vacation, but I will contact him tomorrow.
11-27-2002, 12:58 AM
#12
vacation
Hey man, dont bother him. I posted this here because its not super important and I thought some others might could use the info. Im not going to be able to fly for at least a week and I had figured I would just pull the motor and send it in to have it checked and have the upgrade done. Just picking your brain, cause i couldnt figure it out. Let him have his vacation, he needs it.
Scott
I'll check for restrictions in line and pull UAT out.
Scott
I'll check for restrictions in line and pull UAT out.
