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HelicopterTurbine Helicopters › Turbine cut-out mid flight - white smoke!
12-29-2009 12:29 PM  7 years agoPost 1
iandavidson99

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Ipswich, England

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Today I took my recently acquired Predator Turbine out for a flight and after doing some simple figure of eights, just for fun I gave it full throttle to discover her climb rate. After rocketing up to about 100ft she suddenly cut-out with white smoke coming from the exhaust.

Thankfully I managed to semi-auto her down and limited the damage to a single broken skid, but what could have caused this to happen?

The ambient air temperature was around 4’C and it was half way through my first (and only!) tank of fuel of the day. The only aspect I can’t quite recall is whether the cut-out happened when I had the throttle full open, or more likely I feel, when I eased back on the throttle to halt the climb.

Any help/suggestions would be hugely appreciated - next time I might not be so lucky

As always - many thanks!

Ian

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12-29-2009 01:30 PM  7 years agoPost 2
Rappy 60

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Paris, France

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but what could have caused this to happen?
My guess is that your deceleration value is too low in the ECU. You might want to raise this value up to avoid flame outs. There are basically two values that affect how fast the turbine reacts to throttle inputs.

Acceleration and Deceleration.

The acceleration value will determine how fast the turbine spools up, however if it spools too quickly this can cause a flame out, therefore the acceleration value directly affects the turbine from zero to full throttle climb outs.

The deceleration value will determine how fast the turbine spools down, again if it spools down too fast it can cause a flame out, therefore the deceleration value directly affects the turbine from full throttle to zero during descending maneuvers.

I typically like to have a good acceleration (lower number) response and less deceleration response (higher number), that way the turbine does not fully spool down and has power available for quick transitions.

These values are available to tune via the hand held terminal.

Typically I will either add or subtract by 1 from the default value and test climb outs and descents (close to the ground) to see where the engine flames out. I then bump up the numbers by 8 or 9 points for a safety zone.

Hope this helps out,

Dale

Load "*",8,1

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12-29-2009 01:55 PM  7 years agoPost 3
iandavidson99

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Ipswich, England

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Hi Dale,

Many thanks for your prompt and comprehensive response. Having now checked, my current settings are as below - are these similar to yours?

Acceleration Delay... 020
Deceleration Delay... 030
Stability Delay... 050

One theory I conjured up while returning from the flying field, was, could it have possibly been caused by oxygen starvation due to the canopy restricting the air-flow needed into the turbine when I asked for full throttle?

Cheers,

Ian

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12-29-2009 02:12 PM  7 years agoPost 4
Rappy 60

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Paris, France

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One theory I conjured up while returning from the flying field, was, could it have possibly been caused by oxygen starvation due to the canopy restricting the air-flow needed into the turbine when I asked for full throttle?
Don't think so.
Acceleration Delay... 020
Deceleration Delay... 030
Stability Delay... 050
Start by adding 5 to the deceleration delay (035) and see if this makes a difference. I don't have my turbine settings here, but they will differ to each turbine. You can test this by just spooling up to zero pitch on the blades on the ground (like you are getting ready to take off) and dropping the throttle to zero (idle).

Dale

Load "*",8,1

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12-29-2009 02:23 PM  7 years agoPost 5
iandavidson99

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Ipswich, England

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Hi Dale,

Great, I'll give that a go and see how I get on. Many thanks again for your help and advice.

... I now need to go and purchase a new set of skids :-)

Cheers,

Ian

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12-29-2009 03:57 PM  7 years agoPost 6
MattJen

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UK

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up your deceleration to 50.

that is what mine is on.

Also,

can you list your throttle curve ? as something maybe a miss there,

it may just need upping a couple of points on your throttle curve,but if you can list the points/values you have it will help us help you a lot

failing that, i am off for a few days in a couple of weeks am happy to meet up and check it over if you want.

Matt

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12-29-2009 04:52 PM  7 years agoPost 7
MattJen

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UK

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Hi Ian

Sorry I have had a late night, getting used to being a baker, LOL,
I am certain i know what the problem is now,

What type of fuel tank do you have ?

What fuel pipe are you using ?

Can you put up some photos of how it is connected to the pipe,

Big clue here, you have almost certainly got a fuel problem... but still set your accel/decel to 50, but this is an unrelated issue..

Sorry i realized this after re reading your post....

Also,

A download would be vital if you know how to do it, would be a great help, and i can positively confirm my fuel starvation suspicion by looking at the download data.

Matt

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12-29-2009 04:53 PM  7 years agoPost 8
iandavidson99

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Ipswich, England

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Hi Matt,

Many thanks for your input and deceleration setting. I like the idea of possibly meeting up, so I’ll PM you about this!

I have a DX7 so only a 5pt curve. I’ve set my curve to 0, 70, 80, 90, 100. Hover occurs around mid-stick (so 80), but it’s quite possible that after my rapid climb I could have pulled the stick back to 25% (so below 70) to initiate a spritely (but definitely not manic) descend.

That said, the engine cut out before she really had time to change direction at the top and come down under power. Currently the maximum RPM is set to 130,000.

As a side note, where is the best place to get spares (e.g. skids!) for the Century Predator in the UK? I have a great local model shop, but I'm sure if I mention anything to them other than Align, they'll scratch their heads

Cheers,

Ian

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12-29-2009 05:08 PM  7 years agoPost 9
MattJen

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UK

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Hi Ian

Sorry, originally i read this thread when i was tired,got carried along with the drift of the topic, ie acel/decel,

After re reading your post properly i realize this is very likely a fuel feed issue..changing your decel/acel wont do anything or cure this problem.

This is a classic symptom and has happened to more people than i care to remember..

A data download would go towards confirming it beyond all reasonable doubt.

Matt

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12-29-2009 05:21 PM  7 years agoPost 10
iandavidson99

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Ipswich, England

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Hi Matt,

Thanks again :-)

I've taken a couple of photos (hopefully atttached to this posting - notice the broken skid!), but if you would like any more, please just say.

[img] /helicopter/gallery/80519/Mobile_Photo_29_Dec_2009_17_17_17.jpg [desc]
[img] /helicopter/gallery/80519/Mobile_Photo_29_Dec_2009_17_11_43.jpg [desc]

I have also downloaded the data from the FADEC, but I'm unsure where to upload this to so you can get it?

Cheers,

Ian

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12-29-2009 05:30 PM  7 years agoPost 11
MattJen

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UK

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hi Ian, Can you send a photo of the following

CLOSE UP OF all your fuel pipes leaving the UAT..

To get a get a download up onto the post, just copy and paste..

The skids you can get from centruy Uk, and dont forget to check your blade grips and thrust races after a heavy landing.

Matt

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12-29-2009 05:48 PM  7 years agoPost 12
Rappy 60

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Paris, France

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up your deceleration to 50.

that is what mine is on.
Matt, just because your setting is 50, does not mean that his should be 50 also. Again, the acceleration and deceleration settings are based on the engine and they will be different for every engine. Setting it to 50 (which is high) will isolate it if its a fuel problem or not but he should not just set it to that and forget about it. He stated that he did a fast climb out and if it was fuel starvation then I doubt he would be climbing that fast and would of flamed out during the climb out, not after he started to descend. But then I guess your the expert so I'll leave it to you. Good luck

Dale

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12-29-2009 05:48 PM  7 years agoPost 13
iandavidson99

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Ipswich, England

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Hi Matt,

Sorry for the grainy quality of the photos, there were taken with an iPhone. As before, please just say if you want more.

As for the FADEC data, is it really ok for me to cut 'n' paste a 6000+ line 143kB text file into a forum posting?

[img] /helicopter/gallery/80519/Mobile_Photo_29_Dec_2009_17_42_06.jpg [desc]
[img] /helicopter/gallery/80519/Mobile_Photo_29_Dec_2009_17_41_19.jpg [desc]
[img] /helicopter/gallery/80519/Mobile_Photo_29_Dec_2009_17_41_52.jpg [desc]
[img] /helicopter/gallery/80519/Mobile_Photo_29_Dec_2009_17_41_32.jpg [desc]
[img] /helicopter/gallery/80519/Mobile_Photo_29_Dec_2009_17_40_50.jpg [desc

Cheers,

Ian

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12-29-2009 06:10 PM  7 years agoPost 14
iandavidson99

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Ipswich, England

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Hi Dale,

I'm very much a newbie to turbines, so hugely grateful to both of you for your advice. I will be taking it all onboard :-)

Just to clarify, I'm pretty sure the 'flame-out' (well, I didn't see any flames only white smoke, but that seems to be the right term) occurred when I halted the climb abruptly and tried to bring her down swiftly

Thanks again,

Ian

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12-29-2009 06:11 PM  7 years agoPost 15
MattJen

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UK

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Hi Ian, it's hard to see anything on the photos, I think at this stage the data readout is what we need. If you havn't run the engine at all since the flame out you could copy in just the last 50 lines because that is the bit I need to see.

The fadecs are not set to each individual engine they are a just general setting for that engine Wren say. Some owners do try to tune the set-up to more agressive settings on the fadec but this is not recommended by Wren. A 50 accel 50 decel is a slightly softer more reliable older engine setting once used by Wren, but as I said it's not really the issue here it's just one that slows the engine throttling very slightly.

Only a download will reveal a clue as to the actual problem which sounds like fuel starvation due to pulling in air during a full throttle climb.

Matt

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12-29-2009 06:19 PM  7 years agoPost 16
ppridday

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Detroit Lakes MN

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I had the same issue with my MW54/Predator as well and it did turn out to be a fuel issue. I was drawing air from somewhere on the inlet side of the fuel pump. As Matt said a data dump showed it up easily. The area that I believe caused it was at the fuel pump itself. Bell Bloke had some ideas for me to try out and it seems to have cured my problem. This basically was using a smaller diameter fuel tubing all around and then wrestling it over the tank piping and fuel pump nipple. I have only had about four flights on it since the fix (Which is sad seeing as it was about 7 months ago) but have had no flame outs at any throttle settings.

Paul

"There's someone in my head, but it's not me..."

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12-29-2009 06:30 PM  7 years agoPost 17
iandavidson99

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Ipswich, England

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Below is a link to a dump of my FADEC data

http://dl.dropbox.com/u/267254/fadec.txt

It's a .txt file, but you should still be able to open it in Excel as a .csv

After the landing(?) I tried a few times to start it again (which the data will probably show), but it wouldn't fire. I'm not too worried about this however, as I was probably out of gas.

Cheers,

Ian

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12-29-2009 07:12 PM  7 years agoPost 18
MattJen

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UK

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Hi Ian, the data shows what looks to be a lean cut at page 34.
This means its air in the fuel. You can see on the data that the stick is at full power and the pump is pumping hard, rpm is up at 115,000 then suddenly out goes the flame indicated by the temp drop even though the stick position and pump rate remain unchanged and then the engine begins to spool down.
You can even see that the pump does not stop until the engine is at 31,000rpm hence all the white smoke you saw.
The data shows even the speed of your reactions too.
Accel Decel rates only come into play when rapid throttle changes are made, and you didn't make any so this points to fuel feed problems or air in the fuel.
Hope this helps

Matt

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12-29-2009 07:34 PM  7 years agoPost 19
iandavidson99

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Ipswich, England

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Hi Matt,

Thanks for that - that's extremely helpful!

So, if air got into the fuel, does that imply that my rapid climb followed by an attempt at a spritly decsent had nothing to do with it flaming out, or how could the two be linked?

What could have caused air getting into the fuel, or is that opening up a whole new can of worms? Perhaps we should meet up

Cheers,

Ian

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12-29-2009 07:56 PM  7 years agoPost 20
MattJen

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UK

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Hi Ian, yes the two are linked.
Because you have a fuel system fault when you gave it full throttle your fuel pipes started drawing in air due to the increased fuel demand. That's not to say that you can't fly it hard, Bell thrashes his to within an inch of it's life but his fuel system is good.
The pipes on your fuel system look very old or prehaps they are the wrong grade for jet fuel, replacing all the fuel lines to the engine and putting inserts in as ppridday suggested will fix the problem.
I will pm you Bells number as I have to go to work now, he is expecting your call.

Matt.

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