Hi

Today at the field, while I was starting my P160 SX turbine, but forgot to open the Festo manual ball valve before start-up. During the start-up sequence I opened it up and due to pressure build-up in the fuel system had a wet start.

The pipe is a bit discouloured and it as 2 small boses. The soldering joints are ok. Should I replace the pipe or can it handle more flights? I can post some pics later on.

Also the F4 seems to build up quite heat in the under rear of the fuselage, due to exhaust. Elevators and underside of the tail seems to heat a bit. Is this normal?

The plane and the pipe are from earlier kits. Don't know if there was an improvement in SM pipes, but it sure should handle a wet start

Regards

Nuno

My Dear Jet Nuno, I am sorry to hear that you had an Hot Start, I am quite sure you did not disconnect  the Kerosene tube  from the
turbine before you proceed with the primming process, that is very common to happen because if you do not do that of course the
turbine gets flooded  without  you notice and  when you start the turbine it  will have for sure an Hot Start or Wet Start,  as you wish
to call it,  or you have what you call ball valve in the wrong place, to be honest it is not a good idea to have this ball valve in any part
of the fuel circuit,  this does not help at all, as you experienced,  that only caused you problems.
All this is referred on the manual,  I also advise, if you are a new comer to turbines,  you should practice on a test bench the first few
runs before you fit the turbine in to the model,  also as a  beginner,  it is advisable to have a CO2  extinguisher near by at all  times, 
in fact,  if  you have done all I am telling you now,  your exhaust tube and the model would be OK by now.
By the way, have you a Jet Cat official distributor in Portugal?  It might be a good idea to go and see them and ask for help, I am sure
they will help and teach you how to operate with your turbine safely,  avoiding you having further damage on the model and turbine.
I live in Cape Code, ( Boston area) I will go to Portugal next  August on holiday,  if by  then you still have problems I will be very pleased
to introduce you to this first steps on turbines to avoid all this problems you have had.
Take care.

Jetnuno is far from being a beginner.

The rear of my F-4 doesn't get very hot and I am using a P-200 and a Tam pipe.

Jet Flash,

Since you fly in the US, you do know that AMA turbine regs. require a manual shutoff valve in the fuel system, right? Personally, I've never had to use it for safety purposes, but I know of instances where that was the only thing that saved the plane from being a flaming lump. Also, its a very good precaution to keep from filling your turbine with fuel when fueling the aircraft in case the electronic valve does not close completely or effectively.

Bob

Why would not be adviseable to have a fuel cutoff valve in the fuel line? I have yet to see a setup that does not use this feature. Matter of fact I once saw an engine have a fuel pump failure, running away resulting in a horrific fire, and without the fuel cut-off valve, it would have been much worse. Sounds to me like something all of us may have done in the past. jetnuno, I don't own an F-4 so I am not going to comment on your pipe problem, but I am sorry to hear of your problems. Take care.
Tommy

My .02... Flyable SM F-4 $10000.00 Up, New Pipe Under $400.00. Get her Ordered... This is a Bifurcated pipe here...But Hay... You Know make the call.

Hi

Thanks for your replies. I am about to order a new pipe, but took some photos. There is a small bose inside the pipe and a brownnish that I gently scuffed with scotch-brite. The soldering joints are rock solid.

I guess I'll maiden with this pipe untill new one gets in.

Jetflash - How can you be so sure about something you didn't witnessed? Fyi, the fuel sistem was properly primed and if you read my previous post carefully, you will understand that this happened because I forgot to open the ball valve during start-up. I never started a turbine, both in test bench and in airplanes without a manual ball valve. This is a must for safety reasons, eventhough they are not included in the JC turbine package.

I know the "official distributor in Portugal" you refer and I can assure you that I'll be better on my own. Regarding the kind help you are offering me, would be nice to know a little more from you and your experience regarding jets.

Enjoy your vacation in Portugal

Best regards

Nuno

In matter of fact, I never use shut off valve on my models and never had any problems, for what I have noticed, there are more cases to have problems with the cut off valve than without, this is the reason why I prefer this way, maybe one day I might change my mind and if I have to put a shut off valve I will place it before the pump at least will not in put any pressure on the fuel system.
I also do not use any switch for the turbine battery I connect it direct to the ECU, believe me, the more accessories we use in between the more things can go wrong, this is my opinion, of course, we all have different approach on the same matter, I have been flying jets quite for some years and what I am saying here has been very positive but does not mean I am 100% correct.
Please forgive me the ones who do not agree with me.
Regards

If that picture shows the pipe after you buffed it with scotch brite and it is ''bowed'', in other words warped, then the pipe is damaged IMHO. The weld spots would have to get very hot for them to break - but it could be possible for the metal walls, themselves, to weaken and collapse under thrust and heat if they have been heated enough in the first place via direct flame for a long enough time to weaken them.

Only you know how bad the pipe looked before the touch-up and how warped it is. It's hard for me to tell in the pictures but I'm definitely ''conservative'' when it comes to these types of situations so please take that that for what it is worth. I wonder if your hot tail is a sign of a pin hole leak in the pipe or a crack. Is it a dual walled pipe?

Hi Jet Nuno,
you are right, I should have asked you first how you did it, and comment afterwards, sorry for that.
Please see my previous post, I explained there why I never use shut off valves and as you experienced shut of valves is not as save as most people think that is, It is more common and often one forgets
to open the shut off valve on the start up sequence than the pump to have a failure, I am not that wrong, am I? For what I could understand you do not trust the Portuguese Jet Cat official dealer, in this case
why don´t you contact Jet Cat in Germany for advice? Unless you don´t trust them either?
By the way, if that hapens again, instead of open the valve during the start up, it is better to abort it, disconect the fuel line from the turbine, open the valve to realese the pressure, connect it and start all over
again, this is the way how I would do it if I had a valve fited.
I am sorry to have mistaken you as a beginner, for what I can see now, you probably have more experience in turbines than I have, in this case keep burning, eventually you will get there, we all know,
learning with mistakes is the best way to improve, if costs are not a problem for you.
I might sound a bit hard to you but I only sincerely wanted to help.
Regarding your exhaust tube after the wet start seems OK to me, according of course with the picture you show on your post.
Regards

Hi Eddie

The pic you refer, is before I scuffed it with scotch-brite. Now it as a smother surface. The pipe is twin walled pipe from SM. Attached there's another pic.

The plane is a F4 and in this plane the pipe ends before the tail plane, heating it up a bit. Next time I'll start the turbine, I'll measure the temperature in the elevator.

Regards

Nuno

You know what, I can't really see a single area in the pics that is a certain failure point except for the suspicion that the warping in the pipe wall before the bifurcation may be a sign of metal that has stretched (weakened) under heat and air loads during the hot start - but I can't also say that I know the pics really show the whole picture either - it is inconclusive. There was a thread a while back on the debate points of weather a wet/hot start is dangerous for further use of a pipe. It seems it was about one to two years back. A lot of very informative information. Do a search and see that thread. You may find some information on that thread that may convince you to either keep the pipe in the jet, or replace it. I wish I could give you more information. All my pipes have been straight pipes, I've never used a bifrucated pipe - so that is a further complication that I can't offer insight on.

Nuno,

I have a SM F-4 using the SM pipe and the bottom of the stabs and the area above the tailhook has always gotten warm. I've watched those areas closely for any signs of heat damage and have never seen any.

same here. just make it part of your post flight or pre-flight inspection

Just put the valve inline before the pump..... or not??????

Hi

I never use any valve, reduction or any acessory in the suction side of the pump. The anwser to your question is, don't do it. Remember, Festos were design to work under pressure, not suction.

Regards

Nuno

Best I can tell from the pictures, I notice the outer pipe is gold colored, indicating the inner pipe must have gotten pretty pretty hot. Gold color OK, extensive areas of 'blued' metal, however, indicates tempering (softening), i.e., the pipe has lost its stiffness. If that's the case re the inner pipe, it becomes subject to collapse at full thrust (Bernoulli effect). If the blued portions can be permanently deformed easily (dented), then that pipe should be replaced.

Just curious Jetflash: you mention you live in the Boston area....'Cape Code'. You mean Cape Cod? That's where I'm from and the only turbine guy around, to my knowledge. Where do you fly? And absolutely nothing wrong (and much to be gained!) in using properly installed (tubing ends square, pushed fully in) Festo products on the suction side. I prefer a ball valve there, to on the pressure side, where mine are straight runs from pump to turbine. Festo products are actually manufactured for pneumatic uses, pressure and suction, but it's certainly been proven worldwide over the past fifteen years that they are fully reliable in our installations!

Ray<br type="_moz" />

Hi guys

I have ordered a nw pipe from Skymaster and after a lot of work finally got the one I was looking for...

This pipe is more angled in the final exit than the original one, thus forced me to set the turbine standoffs in a different manner. The pipe in the picture is the original, but the new one as a bigger angle.
My concern now is the angle that I have in the turbine regarding the fuse.

This angle is quite big, but it is the only possible position to align the turbine with the pipe. I also have lowereed the finnal exit of the pipe to align the pipe regarding the turbine and the fuse axis. This as lowered the exhaust and helps protect the elevator.

My question; what do you thisnk of this set-up? Is the turbine very angled regarding the fuse?

Best regards

Nuno

Hi Nuno
I just checked mine again it is no where near that it is only 3 degrees down you better sort it out before you try and fly it mine is a ***** cat I love my F4

regards

Andy

My turbine is nearly straight. I will double check once I get home next week.

Nuno,

That is too much of an angle on the turbine. You should have 3-5 degrees max. There should be mounting blocks glued to the former and below the turbine mounting rails to which the pipe straps bolt to. In other words, the pipe mounting straps will be below the turbine mounting rails. Hard to tell from the pics how you have the front of the pipe secured.

Hi

Thanks for your replies.

I took some pics of the old pipe and found out what the problem is. The new pipe is not properly built. The exhaust angle is bigger in the new pipe, so to have the exhaust exit straight, The angle in the turbine as to be bigger. Pic. 3 is new pipe and pic. 4 is older pipe. As you can see the angle is quite different.

Unfortunately, it is the second time Skymaster send me an incorrect pipe and I am waiting for more than 4 monthes to maiden this plane[:@][:@]

I have already reported this problem and asked for a correct pipe for the second time and no reply till now. I will be at JetPower and return this to them. Hope to have a correct one, FINALLY...

Regards

Nuno

You could also order a pipe from Tam.

Hi Dantley

At the time I asked for a quote, but went the cheapest way. Turned out to be the wrong way. 5 monthes gone and no pipe, but hey Skymaster is the plane manufacturer right? And the first was a good one...

I guess SM will deal with the issue the right way

Regards

Nuno

Nuno, my setup looks different than yours. First my pipe appears to be wider than yours. I see you had to add an additional wood pc to seat the rear of your pipe. That P160SX is rated at the same thrust as my K170. I'm not sure that the pipe you have is wide enough for that P160SX. I had Tam's make my pipe for the P160SX and later put in the Kingtech. I just don't like the pipes these chinese companies provide. I don't think they are consistant and have had them fail before. I have no problem with heat on the rear. The plastic tailcones are slightly discolored on the bottom from heat but it's not deformed and the paint isn't affected. There is approx 50 flights on this jet.

Second, the angle of your turbine is much greater than mine. Something doesn't look right here. Can you send another pic showing how the turbine and pipe is mounted?

Here is a picture of my install: