Power drop on fast acceleration

[rkeith2]

I was flying yesterday and puched out full stick on the Wren 54 which I usually do when I am showing off the Bergen and the power dropped off where I was preapred to auto in.

As I dropped the stick the power picked back up again. It happened 2X so I did not try for a third and just flew and did some 3d in idle 1 since the engine sounded fine -

Ideas? History?

[chopper jockey]

was your power drop off due to rotor speed decay or was your turbine slowing down?

[Greg Alderman]

Ron...did you download the FADEC data? Possibly sounds like you could have hit the 800C max temp and the FADEC dropped RPMs until temp dropped...I have yet to see this happen on mine but did see in on a JetCat at a flyin in PA a month or two ago...

[rkeith2]

Greg -

I did not even think to look at the GSU data. Would it still be there as a last event or do I have to get it while its hot?

[Greg Alderman]

no the only thing the data display would see was the temp at shutdown...to see the stored data you would need to down load it to a PC...the FADEC stores the last 59 minutes worth of data...the data is updated every .5 secs so you can get a good feel for what the turbine is doing...gives RPM, EGT, Pump Voltage, throtle position...

Greg

[chopper jockey]

Its very unlikely a wren will max out on temp during flight, no matter how fast the climb out is. It is more likely to be either the clutch is slipping or the second stage wheel is cavitating. I had a similar effect on my acrobat when the standard drive belt started to loose teeth, the head speed would decay at full climb pitch and recover during the descent, the turbine was fine. :wink:

[rkeith2]

Let me clarify a little here - if the clutch was slipping the turbine power / speed would escalate.

The turbine sounded like I was bringing the throttle down.

[Heli_jack]

I doubt if this would be it, but a friend of mine had a power issue on a JetCat on a hard punch, and found out his servos were traveling too far and he was stalling his servos and lowering his voltages enough that the ECU shut it down.

Again I doubt it, but something to look at.
Jack

[cbergen]

Any chance you turned on some cyclic to throttle mixes recently??

What mode were you in when it was dropping off?

Idle 1 was OK, No power loss doing aerobatics?

[rkeith2]

I was in idle 2 where the mid curve is about 40 then ramps up to about 70, 75

All the 3D stuff was okay and she sounded fine, it was just the 2 punchouts ...

No FOD, no other problems I could find.

I am going to San Diego Saturday and will do a noontime demo and would like to have a solution before then. I have done some pressure dropping normal mode full power climbouts and never had this occur so i am assuming something changed somewhere.

I will go over the 9303 again to MAKE SURE I have not added something. I have not messed with the Turbine setup on the TX for quite a while.

me

[Gary Travis]

Ron
With the 9303 radio ,make sure you have the pitch and throttle levers on the side of the radio disabled.
Gary

[rkeith2]

I always disable those sliders first thing on all models ...

Getting ready to go thru the fuel delivery system tonight and see if I can find anything.

[rkeith2]

Debris in the fuel line and loose fitting again at the combustion entrance.

Tightened and flushed = should be good to go.