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HomeTurbine✈️Aircraft🚁HelicopterTurbine Helicopters › JetCat PHT3-3 shutting off in mid air due to: Over RPM
07-27-2013 07:47 AM  6 years ago
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Thomas Ekdahl

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Tønsberg, Norway

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JetCat PHT3-3 shutting off in mid air due to: Over RPM
I was enjoying som flying with my Vario Bell 205 with JetCat PHT3-3 yesterday. Nice weather, no wind, 24 degrees in the shadows.

After doing some normal flying I decided to do an almost full power climb out. When reducing power and pointing the nose down for forward flight at the top of the climb out, the turbine just shut off, forcing me to do an autorotation. (To auto this 20Kg bird is my worst nightmare).

Fortunately the auto went better than expected, more like a heavy controlled landing. I did not feel I had a lot of power left at the bottom of the auto, but enough to slow things down considerable.

The damage I have seen so far was some scale details fell off, and small damage to the blade root, and a very small bulk in the middle of the same blade.

I have measured the main rotor axle and the spindle - and it does not show any signs of being bent.

1. The turbine Last Of cond was: Over-RPM
>Turbine exceeded the maximum RPM, by 5% and a delay of 0.5 seconds - >then engine turns off................

What kind of behavior is this? The ECU deliberately shuts down the turbine for a condition solved 2 seconds later........... Watch out for this.

I have asked JetCat if I can tweek these settings, I would much prefer to fly with slightly higher RPM for a few seconds than having the turbine shut down in mid air. I would change it to like 10% over RPM for 5 seconds. The mechanics should tolerate this, when it is due to a full power climbout and reduction in power afterwards, resulting in over RPM for a very short period of time.

I consider this behaviour a bit dangerous, what do you think?

2. Can I fly with the lightly damaged aluminium blade (Vario original 413/5). Se pictures. Or is it best to change it?

https://dl.dropboxusercontent.com/u...io/DSC_1955.jpg
https://dl.dropboxusercontent.com/u...io/DSC_1956.jpg
https://dl.dropboxusercontent.com/u...io/DSC_1957.jpg

3. Other mechanical / structural things I should check or replace after this incident?

Thanks.
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07-27-2013 09:39 AM  6 years ago
modtron

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Oxford. UK

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Thomas,

What rpm is your engine set to -94000 / 98000 ?
It should only see an over rpm if it went over 100000.
Did you use the GSU to see the Max rpm and MaxR temp reached during the flight ?

The say the temp was 24 in the shade and no wind - it could be that with the enclosed location and obviously high outside temp, that that could also have been part of the issue.

I have the same set up in my own 212, but there is more room around the engine for air flow, where as in the 205, it is a lot tighter ?

When you contacted JetCat, what did Roman say about your issue ?

As for the metal Viper Blades, you would be best to consult Vario or Jung about the damage - the damage at the root and the skin profile is unknown without using xray equipment.

Our ruling for the UK, would be "no longer useable under any circumstances".

A for checks - check the tail joint area, as it is a know week point and can fail very easily.

Sorry for your problems, but I hope you get a solution sorted.

modtron
Oxford UK
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07-28-2013 05:58 PM  6 years ago
Thomas Ekdahl

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Tønsberg, Norway

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Engine RPM set to: 94000, 960 RPm on rotor head

RPM at shutoff was: 107600RPM
586 deg shut off temp
1.2v pump at shut off.

Avg RPM 90700

656 deg max temp
398 deg avg temp
1.82v max pump
1.1v avg pump

From the logs you clearly see the power climbout as the highest pump volt on the flight. When dropping from 1.82v to 1.2v it overspeeds RPM and shuts down.

Everything else looks to be below max margins.

Logs:

https://dl.dropboxusercontent.com/u...02013-07-26.log

Regarding outside temp, yes it is not often this warm when I fly, thats why I think it was important to mention it, but it looks like the turbine temperature is well within the normal.

I mailed Roman friday afternoon, I do not expect him to answer before monday at earliest (then I'm very happy).

As for the blades, I will no go to the length to x-ray them. If a replace is whats recommended, thats what I will do (checking with Vario).

Thanks.
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07-28-2013 06:09 PM  6 years ago
modtron

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Oxford. UK

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By the sound of your description, it looks like the pump voltage increased during the climb out and then when levelling off and the nose being dropped, that is when the rotor unloaded which allowed the turbine to over speed.
The ECU then saw this and reacted by shutting down the engine.
Not ideal by any account - not to sure what way to resolve it either ?

I hope you get a response back from Roman, but he is very SLOW to reply and JetCat also shut down during next week for annual holidays.

It may be worth emailing either Sandra or Saranda and ask them to get Roman to reply ASAP.

modtron
Oxford UK
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07-28-2013 06:49 PM  6 years ago
MattJen

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UK

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that is when the rotor unloaded which allowed the turbine to over speed.

Just an idea maybe adjust your pitch curve so the engine doesn't unload too much ?

139 94750 94000 486
140 95730 94000 467
141 96770 94000 432

reason i say this, it seems your engine is not under load hence it is over speeding by nearly 2770 rpm.

There will always be a delay between stick input and turbine response as turbines are inherintly laggy.

Anyway it is just an idea..

EDIT..
Is there any chance the clutch could be slipping ?
All The Best
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07-28-2013 07:21 PM  6 years ago
Thomas Ekdahl

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Saranda is on CC on the mail, as is Christian. But I think I will call tomorrow morning to get an answer as fast as possible. But Roman does not always answer my phone calls either.

Modtron - I think you describe the situation correct, this is what I feel happended.

MattJen - If you see the pump voltage from 139 to 141, it just looks like I'm applying more pitch and the engine playing catch up. The pump voltage increases when low RPM, and decreases on high RPM. (Just my thought)

Regarding slipping clutch, interesting theory. I don't know how I could check that out. When flying it does not feel like it is slipping, no signs of excessive wear or material buildup around clutch. The engine has under 12 hours runtime, and 60 flights, so I hope this is not the case.

Regarding pitch curve. I think it is impossible to make a curve that does not unload the engine to much after a high power climbout. I do want to stop the upwards motion, so I don't see how this curve should look if it should work in other situation (suggestions welcome). I think a delay on the pitch channel would have solved it (making the change from one point to another take more time, letting the engine normalise the load). But to delay pitch input would probably make some other interesting problems (But this would be possible on my transmitter I think (Jeti DS-16), and the delay could be short, like 1 second. It would be good to solve this problem in the ECU, or the transmitter, but for now I only see the possibility of not making sudden pitch movements, but even smoother - but this is not a good solution.

Maybe we should feed the pitch channel to the ECU too, so it can know the expected power needed before it happens (as a modern 3 axis gyro), and also see that the reason for overspeed is less pitch, and just accept it for a few seconds). This is a tip to JetCat.

Thanks for all tips.
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08-02-2013 07:37 AM  6 years ago
Thomas Ekdahl

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Status for now:
- Mail sendt to Roman, Saranda and Christian at JetCat on friday - no answers yet (1 week waiting)

- I have called Roman on his direct phone 5 to 10 times each day since monday without getting an answer (but sometimes the line is busy, sometimes he never answers and sometimes he closes the connection (I can hear this and it really puts me of). They call this number a "hot line".

Udo has answered once but he does knot have knowledge about helicopter turbines.

And JetCat holiday is next week.

That means that I have to wait at least 2 weeks before any answers (in my experience we are talking months), and all flying action has the same delay (If I have to have replacement parts or send the turbine in for service - everything will be delayed since I don't get answers to the questions I ask so I do not know what to do.

I think the JetCat products is good, but their customer service is worse than anything I know, so I would not recommend buying a JetCat product if this is the kind of service they give every normal non privileged customer.

The problem is that only Roman knows the helicopter and turboprop turbines, and no other employees. This does not scale very well as a business.

Just my 2 cents.
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08-02-2013 08:02 AM  6 years ago
modtron

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Oxford. UK

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Thomas,

I know your problem and while not defending JetCat, I do know that things may well change with regards to servicing times.
I have had conversations with Marcus about the situation and he does understand but cannot change things instantly or overnight.
As you say, they are now shut until the 12th, but Roman does still look at emails so keep sending them until you get a reply.

modtron
Oxford UK
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08-02-2013 08:23 AM  6 years ago
PETER ROB

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Devon UK

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Bad customer service
Thomas, I have a lot of JetCat turbines, and found that The JetCat service, is OK when things are straightforward
Answers to problems not in the normal run, are very slow in coming
In their defence, we as the pilots carry out manouvers, to which they are not privy to, so the answer may be difficult
Read some of the reply's here to under stand what I mean

At the moment I have one Jakadofsky turbine, with another on it's way,
The present one was in the heavy landing I had a couple of weeks ago
I emailed Peter Jakadofsky as to what his thoughts were to what I should do
He said their workshop was very busy and he would not have a slot to look at mine until August
Yesterday 1st August, emailed me to say they had stripped my turbine and found bearings needed replacing, plus electrical components were damaged, he offered me a quicky turn around, but if I wanted the Kero start fitted, it would be 4 weeks turn around time
I opter for the quicky return, I received the invoice yesterday evening, paid by internet transfer, as soon as the funds are received by their bank it will be shipped back to me
I am expecting delivery early next week
Now that is what i call service
This may not be the cheapest option, but for peace of mind and getting it fixed correctly the first time, it will always be my option
Peter R
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08-02-2013 08:38 AM  6 years ago
Thomas Ekdahl

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Tønsberg, Norway

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Note that I do not require a finished solution from JetCat at this time, I only wan't to talk to them or get a reply "we are looking into this" and will get back to you in x days. If they think a service is need, I just wan't to know now - so I can send it back, instead of waiting 4 weeks and then send it back (because my turnaround is quicker then).

So my frustration goes to not beeing able to talk to JetCat at all. They do not answer my calls at all.

I have mailed with Jakadofsky earlier and got the impression of good and personal service, my next heli turbine will be a Jakadofsky in a Starwood Lama (on my wish list).

But I have to say that one time last year, when buying a used JetCat turboprop - Roman answerd quick and was very helpful resulting in a buy.
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08-02-2013 08:57 AM  6 years ago
PETER ROB

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Frustrating
Thomas, JetCat blow hot and cold
I have been in your situation a few times with them, but on the whole they are not that bad
I think you have sent the download from your last run to them
Normally this prompts an answer

I can not fault the Jakadofsky Turbine, except to say it is limited in my applications
I do like the JetCat 2 stage
Peter R
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08-03-2013 11:20 PM  6 years ago
chopper jockey

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uk

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If over rpm / over temp. occurs in a full size helicopter, even fadec control ones, the engine is absolutely not commanded to shut down.
Everything is designed to keep the engine running at all costs and let the pilot decide whether to shut down or not.
I think Jet Cat should up date the firmware to show an indication only.
No point in shutting down an engine to protect it if it then destroys itself in a crash.
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08-16-2013 02:47 PM  6 years ago
Thomas Ekdahl

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>I think Jet Cat should up date the firmware to show an indication only.

I'completely agree. It would be nice to have as telemetric data to my Jeti DS-16 Transmitter, so I can decide to land if I wan't to.

I have tried to call Roman / JetCat many times a day this week too. Without anybody answering calls or emails. But some times I feel they "hang up" on mee, and sometimes busy.

My first point of contact was 26/7-2013.

I see the rest of the turbine flying season going down the drain now, because if I have to send it back, the usual turnaround time is more than 3 months including freight times to norway - and then we have full winter here.

You really have to have a lot of turbine models if you wan't to fly regularly.

I'also mailed with another person with the same problem, telling me he had to send in the ECU to JetCat, and that they changed MaxRPM from 94.000 to 98.000 and the problem was completely solved.
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08-22-2013 07:27 PM  6 years ago
Thomas Ekdahl

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Tønsberg, Norway

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Latest status
When not only copying Roman, Christian, Saranda and Udo - but adding Doris to the mail list when enquiring JetCat I suddenly got good response times from Doris.

She talked to Roman, and I was asked to send the turbine back in for service.

= So many thanks to Doris for sort of saving JetCat, I regret not involving her earlier.

The sad part is that if Roman told me to send the turbine back for service a month ago, I would have one month more flying this year. And it would have taken him 30 seconds to tell me and I would have been happy.

With normal turnaround time as I experience it twice last year, I have a 3,5 month wait. That means I get it back in mid december, and the ship will not fly again before next spring.

I have had 3 service returns on 12 hours of flying on the PHT3-3. That means statistically speaking a new service every 4 hours (not 50 as stated) - so I'm not impressed by the quality. Is it only made for hangar queens and not normal usage?

In fact I will put my chopper for sale and try another brand of turbine - so JetCat get rid of me, and I of them.
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08-22-2013 08:39 PM  6 years ago
Thomas Ekdahl

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Tønsberg, Norway

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For sale: http://www.rcmarked.no/detail.php?id=55628

- Serious offers wanted.
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08-22-2013 10:15 PM  6 years ago
PETER ROB

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Devon UK

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over temp. occurs
Thomas, Not sure if this could be of any interest to you
I am new to Jakadofsky, and sent a turbine back to Jakadofsky after a very hard landing
Jakadofsky advised me that they could not check my turbine over, until August, so I returned it in the last week in July
On 1st August I had an email from Peter Jakadofsky saying it needed bearings replaced, I authorised the work, received the turbine 5 days later
Thats good service
Ok reading through the manual, there is a part which may be of interest to you
Do not over pitch, if you do the engine temperature will rise, if it rises too high the turbine will go to shut down

Over pitching can occur for a few reasons
Firstly, a hard climb out, too much pitch
Low revs, trying for slow head speed, over pitch to compensate for the lack of revs
Over sized blades, turbine working hard

So if you were running with any of these conditions then followed with a hard full stick climb out then the turbine could go into failsafe and shut down
Not sure if this applies to you but I will be checking my turbine temperatures after my first flights with the new turbines
Peter R
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10-09-2013 08:47 AM  5 years ago
Thomas Ekdahl

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Tønsberg, Norway

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Then I got my PHT3-3 back from service.

JetCat tells me the following is done:

>the motor shaft was okay, so they didn´t change also the bearings.
>The EGV was overhault. Software-Update was also executed. with the >new software-Update this problem is solved. There should be no other >problem at all.

This is ECU Version 6.1 I think (have to check)

JetCat does not wan't to tell me what has changed in the new software to make it work, so I have sent them a new e-mail asking for this.

Looking forward to testing it out again.
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HomeTurbine✈️Aircraft🚁HelicopterTurbine Helicopters › JetCat PHT3-3 shutting off in mid air due to: Over RPM
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