kingtech turbine rc engine k70g2 fatal problem
 

Hello everyone,
Has anyone encountered a fatal malfunction with the Kingtech K70g2 engine?
Attached above pictures that describe the results.
I would like to point out that the case happened to another four engines of this kind (k70g) in Israel.
All of them had a FOD screen and yet it was a failure, in addition to another 2 turbines of the same series k70g were sent to repair due to ball bearings They failed. Customers in Israel are concerned that something is wrong with this engine. In the other models like k120,k140, we did not encounter such a problem.

Isaac Berman

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Nasty stuff!

My friends and I have been running something like 8 of these. No failures like that.

My bearing experience was on another model K, but it maybe similar issue: There is a bearing problem with K160 V2s. They admitted to the issue and we have had several Ks with failed bearings. I heard my bearings going bad on 3 sequential starts and sent it in for service after the third time. The repair order did not specify what was wrong, so I called. Apparently "there was a design problem." They replaced the entire core. But, I also noticed the start sequence changed. The start sequence now sounds like there is a short squirt of fuel shot into the turbine before it even turns over for the start (i.e. the pump runs for ~1 second before rolling over the spindle.) However, ...

It sure does look like something was ingested on your pics. but you indicated that there was a FOD. Are you sure it was tight to the cowl? If you had bearings going, from my experience it seems like you should have heard them during the start sequence. But then again, maybe not. I hate it when they come apart. I had a P-90 RXi come apart mid air. All sorts of internal damage but there was no damage to the first wheel's blades. But the last wheel was broken right off and kind of hanging out of the exhaust cone. But once the blades disintegrate, there is no telling what damage will result from the vibrations. Good luck.

Could a bearing failure cause what's in the pics? I wouldn't expect any internal parts to come forward to cause damage to the blades like that, but I've never seen any such failures to have any first hand experience.

My K70G2 has had no issues whatsoever.

I've seen that type of damage on other motors before. A piece broke off one of the compressor blades and rattled around in there, damaging the other compressor blades.

On my motor (that did it twice) the piece was finally ejected out *through* the FOD screen. Initially, I thought it was a failure of the FOD screen and something had punched through and gotten in there. However, upon further close examination of the FOD screen, it was seen that the broken strands around the hole were bend *out* not *in*, indicating that the foreign object came from the compressor wheel itself and was launched *out* through the FOD screen.

This failure has become somewhat less prevalent now that must compressor wheels are machined from billet vs. being cast, but it still happens.

Bob

edit: the motors that I have seen this in were not Kingtechs....

We have found this experience at least 3 motors in Thailand.All damaged motors were checked that FOD screen still been tight and not came apart.
These motors were sent to factory for repairing and have been sent back but the problem is happened again and again.
I noticed the compressor blade that engraved with KT marking may be broken first that make debris destroy motor.
I have reported the problem to Kingtech now and We ban K-70 at our flying club now until Kingtech will solve this problem.
I don't know why they still selling the K-70 model in KT website while they stop selling K-310 that have the same problem.
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Wow, you promoting Kingtech like this...

Was I promoting anything?

You mad?

Awww look friends....

No it is called feeling sorry for people like you two.

All I can say is if I were certain manufactures I would be reconsidering my reps and / or dealers. This juvenile bull***** is enough to turn me off of a product. When I need product support this is not the level of service or professionalism I would expect.

Is this issue only affecting the 70g2? Any current issues with any of the other engine sizes? Barry?

I have a friend with a K140 that did the same thing.. Whatever let go, it ejected out through the FOD screen as well as damaging internals. He sent it back and they blamed the damage on FOD, so they quoted him a nice repair bill. Needless to say, he said it was his first and last Kingtech turbine. He didn't need a company calling him a liar when evidence showed otherwise.
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If there is a design fault I would like to hope kingtech will take care of the problem. I personally have quite a few kingtechs without problems.
this reminds me of the wren 160 saga that bit many of us......

Yes, we are having some K-70 compressor wheel problems, not all, but some. The factory is looking into the possible harmonic or some sort of sympathetic vibration induced damage to some of these wheels. The factory has a new design of the compressor, the initial testing with this new wheel yields a lower temperature and better thrust. So the new K-70 should have a lower full throttle RPM.

We are very sorry for the trouble and thank you for your patience for working with us.

Regards,
Barry

The testing process is lengthy, so no new engine will be delivered until further notice, thank you.

Barry

LET'S KEEP THIS ONE POLITE GENTLEMEN. PLEASE STOP THE FLAME WAR NOW.

I want to keep this thread going as there is a probable issue and some RCU members will be concerned.

Thanks for updating us Barry. I know you guys are dependent on the factory to give us good products and that you guys really work hard to service these for us. Based on my experience, I don't think most folks would complain about your service quality or turn-around times. These products do cost a lot of $s. So there are some folks a turbine failure has a huge impact on.

For the rest of us watching this thread; Being successful in this aspect of the hobby pretty much depends on one's attitude. Ones attitude is a choice. Let me explain.

This "turbine failure" type of thing happens to many manufacturers' products, especially ones that are on the cutting edge of high-performance and technology! . I went thru three P-90RXIs before the manufacturer got them fixed. At the time, I clearly felt they were released to us prematurely. By the end of those P-90 experiences, I had already decided to try another brand, even though in the past, I typically had been very brand loyal. Then, I also watched a friend go thru 3 W-100s before he (and I) gave up on Wren even though Ron's service shop was only a couple hours down the road. I also had two brand new snow-machines that had harmonics occur at 6800 RPM. This would cause the engines to self-destruct. I also had a new truck that could not keep fuel injectors working. Ended up lemmoning it.

The one common thing to my experiences listed here was the products were all what I call "first year production models." I have come to the conclusion that if I do NOT want to be the product tester, never buy a product that is in its first year of production. On the other hand, if I am willing to deal with being the tester, then I will risk buying a first year production model and just deal with any failures. Unless you want to set yourself up for many disappointments, I feel that is a decision you have to make early with jets, . Given that all 7 turbines that I have owned have been back to the shop in their first few hours, I have come to the conclusion that we are the beta testers for all turbine manufacturers. If I was not willing to deal with that, I would be flying exclusively with props. Think about it, … how can a manufacturer test their engines in all the conditions we expose these engine to? If you are not willing to do the testing, … feel free to give me a call. I got a couple nice prop planes I can sell you and I have already tested them, … a lot. :)

Our club typically has ~ 27 jet guys. Based on what I have seen, we all have experienced some sort of turbine failure. I have either witnessed or help troubleshoot many of these. What is also common to our jet guys is they all seem to, at least outwardly, accept the fact that we are the beta testers. They never seem to be ranting on the INet or even at our gatherings. They frequently change brands and most are willing to own multiple brands at the same time. Guess we keep the good ones and the bad ones just tend to take care of themselves, etc. etc. Point being that; How we respond to a turbine failure is an attitude choice. Good attitudes seem to be catching. So are bad ones. Which one do you want to be viewed with? If you can't deal with maintaining a good attitude, then never buy a first year production model!

So when you are faced with an issue to be fixed, be thankful that the Barrys and Georges and other service guys are there. They to are only dealing with the products the manufacturers send to us for testing and the conditions we expose these products to. If you do not want to take the risks that goes with cutting edge technology and high-performance and the conditions we expose these products to, then you may want to reconsider what sport you really would enjoy.

DISCLAIMER: All this being said MAY not preclude me from initially being a bit POed when the next one dies! :)

Barry, I have a fairly early serial # of this engine - if there's anything I can offer to help the process please feel free to PM me.

I have a K70G2 #179 in a TopRCModels cougar. I've had it for a year and has about 20 flights. This is my first KT turbine and it runs fantastic. Now I'm a bit concerned having read through this thread.

If I need to send it in for a checkup please let me know ASAP. I'll be happy to do that. Otherwise I will continue to fly with it in the near future.
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As I mentioned above, I had an engine from another manufacturer that did the same thing *twice*. It came to pass that that engine developed a history of doing that, so when I sent mine in, it was repaired at no cost to me (*twice*). I did hear from other guys with that engine that the first few times it happened there was some push-back from the manufacturer that it was a user problem, not an engine problem. However, after the engines started coming back with the same issue, the manufacturer realized that it *was* an engine problem and they came out with a new compressor and started replacing the ones on the failed engines for no cost.

Different manufacturer, same issue and initial response. See Len's post above - it can happen to any of them...

If you want bullet-proof tanks, go with AMT's or old JetCat P-120's... :cool:

Bob

If you have a concern, your best bet is to call Barry and ask. When the bearings went out in my K-160 prematurely, my friend called about his K-160 and Barry told him to send it in. For us north of the Mason-Dixon, now is the time to send 'er in, if it needs work or modification. Don't forget to send the ECU with it.

The toyota Camry of the rc jet world!

Good I just read the post, because I have been very worried, I am also a holder of one of the first K70G2 and today I will have done with it from 15 to 18 flights and at the moment without surprises but I am afraid it happens to me and I can not land the whole airplane in one piece. I just sent an email to the manufacturer, because I think I understand Barry, apparently it does not happen in all of them but who guarantees to me that mine will not fail!

Equally the wisest thing I think it would be to stop flying and send it for its update, to see that they answer me, I need more light about it!

Greetings.

@Barry
I have a k70 new in the box. Can I get my money back?

HI I have a k70 that is new in the box may I please have me my money back?

Thank you

Please forgive my error in protocol here. I respect the community here for its insite and directions.

I truly did not know this question should not be asked here.

I apologize to all.

Is it ok to post the results of my inquirey here?

cheers
DM

My less than 2 cents opinion would be NO. This is something that needs to be discussed with the manufacturer/ manufacturer's rep in a one-to one fashion. In a perfectly civil world - no problem! But I really don't want/care/need to know whether your (pick an age) engine is refundable or not.
Good luck with whatever you and Barry decide.
Greg

No worries Greg, but yes you can return the engine DM, we would have to inspect before issuing you a refund.

Thank you,
Barry

I personally wouldn't stop flying, but knowing there may be a potential problem, probably keep it higher in the cone, so if there's a problem I could still try to glide it in. But if you are concerned, please feel free to send it in, but we just don't have an upgrade at this point, so it will at least be in the queue.

Thanks,
Barry

To be fair to the investigation process of metal failures, yield strength testing / investigations are very complex. There are many parameters that are considered when coming up with a final report of what went wrong. I hope that when Barry says they are looking into this that they are using a metallurgical lab that identifies material defects and structure failures.

The information coming out of that lab is only as good as the factual information we help provide to Barry on the conditions at the time of failure. The who's, what's, when's and where's are important. A turbine failure for a winter flyer at high altitude and ambient temps in the 20's may not be the same for me who fly's at sea level with an ambient temp of 102F. I remember a time that used turbines being flown in a certain area were being sold here and causing allot of issues. When looking into all this, the people selling them weren't telling folks that they were being flow in a sandy area and the engines were basically getting sand blasted internally.

Again, just trying to be fair to both sides. Failures happen.

Deleted.

The problem is that our flight path only has 160 meters and, on the outside, a lot of rocks and ravines, in short, it is not especially suitable for turbine stops.
And Barry knows if the problem is in all the production of the k70 or all its customers? It seems that there is a customer who has already made 140 flights to his!

Sounds like a really small sample size.... Good thing is, we know KT will stand behind their products. Six more flights this last weekend with our K70's...

Two more flights for me yesterday, rolled over the 420 minute mark without a glitch. Seems surprising to see the only reports (in this thread anyway) of failures are outside the U.S., and I know the engine has been extremely popular here. Coincidence? Though I'm not sure what that might point to if it is even correlated.