Moebius44

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Can you expand on how you came to understand that a 600+ step difference is the minimum value?

Thanks!

Karsten022

Hello,

That's what Alfred Frank from www.Frankturbine.com found out. There were always problems with turbine shut offs with Futaba Transmitters in flight. When these turbines, together with the ECU and the same pump, were installed in models with Graupner transmitters, this error did not occur. Futaba seems to have a lower trim path by default. Then the recommendation came to set the value to at least 600.

Best regards,
Karsten

Moebius44

My Feedback: (1)

Thank you kindly Karsten022.

I too am experiencing puffing events - after spooling down and idle has been established. It can can lead to a immediate flameout. The error code in my case is MINIMUM RPM DROPPED.

What I've learned recently; at around the 5hr mark the fuel pump gear assemblies can exhibit run-in characteristics (gradual pressure reduction) that can cause flameout generating the above error code. The suggestion is to slightly raise Start Pump Voltage (SPV) to compensate for gear wear / resulting reduced fuel pressure. However, I was told by someone else that the SPV is not in-play - once the turbine is running off the KERO fuel line / valve (FYI my system is KERO / KERO). Anyone know definitely?

Note: I recently reduced SPV from the default 0.4V to 0.38V to reduce wet start volume. I will be reversing this to see if the puffing anomaly goes away!

Karsten022

That is right - the SPV has noting to do with your flame out. It is normal that it is possible to reduce the value if the turbine runs a while because the pump in now going better.

The message MINIMUM RPM DROPPED could be 2 faults:
1. The tank tubes are to small --> the negative pressure in the tanks is to high. For tubines over 160 N the inner Diameter should be 3,5 to 4 mm
2. The deceleration times in the ECU are to low. If it is possible to open Menu 9 go to 9.10 an 9.11 and increase the values.
If it is not possible to open Menu 9 go to Menu 1.3 and change to middle or slow.

Best regards,
Karsten

Moebius44

My Feedback: (1)

Thanks, system employs 4mm ID fuel lines. It appears ACC / DEC set to Medium has solved the issue sufficiently to fly. Here's what I discovered today:
- Throttle relearn (733 to 753 steps): no change
- Replace Burner control valve (possible leak source): no change
- ACC / DEC lowered from Fast to Medium: very light / infrequent puff events
- ACC / DEC lowered from Medium to Slow: No puff events
- ACC / DEC raised from Slow to Medium: 3 run-ups, imperceptible puff on first run-up's return to idle, none in 2nd, 3rd

I think I'll stick with Medium and fly without going all the way to idle (no flight maneuvering requirement). Learning how to employ vectored thrust high alpha) during landing, so will need some throttle anyways until over the numbers.

Thanks, if I was just a little more knowledgeable, I could have avoided the trip to the Factory :^)

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Im 2 issues in my behotec jb180 turbine, sometimes during taxing when i increase throttle from idle the turbine goes in to puffs and turbine flames out with msg, "minimum rpm dropped". Second problem is that when i do high speed pass and then go vertical, after couple of seconds in vertical my turbine starts to lose rpm, infact once i thought the turbine has flammed out coz the rpm went pretty low though i had throttle stick to almost 70%, however when I leveled out the plane the rom gradually started to increase reach the correct rpm at 70% throttle. Is this due to weak fuel pump.. Or. Anything. Else?

Moebius44

My Feedback: (1)

This is a known issue. Behotec knows there is an issue.

[email protected]

known issue but no solution?