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Longest service interval-which turbine?

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Old 08-07-2017, 07:49 AM
  #26
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Quote:
Originally Posted by cmp3cantrj View Post
Turbines are not designed for long term, static, high throttle, running.
. Prolonged full power running.
APU's in Full scale jets are made for long term running at high throttle settings. Turbine Electric power units? Jets running at full power isn't the main reason engines fail. They can sit there and run at full power for thousand of hours. This is why planes are now allowed to fly across the oceans with two engines. What truly hurts a jet engine; is the initial start up heating, and acceleration of the engine, again, another high temperature of raw fuel being dumped into the burner can. High heat tends to warp things.

The way I understand the OP, since he is using it for another non traditional method rather than in a jet model, he could actually put 25 hours on the engine in one week. That would be a lot of service visits.

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Old 08-07-2017, 08:24 AM
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Quote:
Originally Posted by Springbok Flyer View Post
AMT Netherlands - been flying them since 1997 and have never had to service any of my engines.

Jan
Same here.... Since 1999, never even had bearings.... God only know how many flights and hours on the engines...

Danno
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Old 08-07-2017, 09:33 AM
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Quote:
Originally Posted by RCFlyerDan View Post
Since time on the engine is done by RPM, .
No! It IS done by time. You might argue that it should be done by rpm - but it isn't.

If you don't believe me then you can check for yourself on a Jetcat engine.

Quote:
this just tells me that you flew your P20 at full throttle a LOT! So, you CAN get 200 flights at reduced throttle prior to the 25 hours.
Actually the model was a very light foamy jet and so it was very rarely at full throttle. Since I retired that model the P20 has been in a mini-avanti that requires much higher throttle settings. Reported engine runtimes after flight have not changed much.

How does an engine run work out?

Startup - typically around 45 seconds.

Check full power and systems - 30 seconds.

Detach gas and attach canopy - 30 seconds.

Taxi/carry aircraft to runway 1 minute.

Taxi back to end of runway - 45 seconds.

shortish flight 4 minutes 30 seconds to timer warning.

Landing circuit and landing 1 minute 30 seconds

Taxi back 30 seconds

Total 10 minutes

These times are based on log data independent of the ECU.
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Old 08-07-2017, 10:58 AM
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Yes because of our long taxiways (maybe 300 feet to the runway) we run our turbines maybe 5-7 minutes longer per run, so we get a lot fewer flights per motor "hour", I guess this only hurts the lifetime warranty/25 hour mandatory service type motors, on any of mine out of warranty, I just listen for the bearings to start making noise, or rough starting /accelerating from a burnt needle or combustion chamber.
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Old 08-07-2017, 12:55 PM
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Any engine will give good service life if its operating environment is clean. Have a number of Vt80's posted at various Universities around the country which study alternate fuels running in lab conditions. All have +200hrs of runtime with the highest being 380hrs at last count. All have the original bearings fitted. The one with 380hrs is now onto its 2nd Starter.
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Old 08-07-2017, 02:07 PM
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I agree completely, lack of gyroscopic forces lengthens bearing life as well
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Old 08-08-2017, 02:42 AM
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we have many JETCATS running absolutely ok, smooth, flawlessly, after 50-60 hs without service, after inspection and service, the engine, bearings and hot parts, are perfect!!!
2 JETCAT P80SE, have 120 hs or more, runing until last saturday!!
we use diesel plus MOBIL DTE LIGHT 4,5%.
but, when the engine have warranty, ( our kingtechs ), i follow the owner manual.

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Old 08-08-2017, 02:45 AM
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in time : AMT = ROLLS ROYCE !!
I saw some engines that runing perfect since 1996 without any service.

jose
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Old 08-08-2017, 03:43 AM
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cmp3cantrj:

As you told me............er wrong!

As you told me, contact JetCat. As I said earlier in the forum, I no longer fly JetCat and haven't for 5+ years. So, I did contact the owner of the engines that I fly. Actually, we are both right and both wrong. I was told and taught several years(8-10 yrs) ago that it was keep by RPM and it converts it to a clock. I guess the new way, like your more modern P20, maybe done with keeping track of the fuel pump's time. Doesn't even keep track of the engine!! Just fuel pump! I didn't know that, and I admit that I am partially wrong. But, my statement of getting closer to 200+ flight is correct if you have one that counts by RPM and fly around at 1/2 throttle a lot. I was wondering why I got a lot more flights then what you were claiming. Your engine, there is no consumer control by the throttle stick.

Here is the return email from Arno at EvoJet:
Hi Dan,we have both:

23:HOUR-METER total running time of pump stored in the ECU

24:ENGINE type and serial number and revs counter total (in millions) stored in the ENGINE

BR

Arno
____________________evoJet.DEAm Parir 4A52379 Langerwehe/GermanyTel.: +49 2423 401163email: we@evojet.de





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Old 08-08-2017, 08:09 AM
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Quote:
Originally Posted by RCFlyerDan View Post
cmp3cantrj:

As you told me............er wrong!

As you told me, contact JetCat. As I said earlier in the forum, I no longer fly JetCat and haven't for 5+ years. So, I did contact the owner of the engines that I fly. Actually, we are both right and both wrong. I was told and taught several years(8-10 yrs) ago that it was keep by RPM and it converts it to a clock. I guess the new way, like your more modern P20, maybe done with keeping track of the fuel pump's time. Doesn't even keep track of the engine!! Just fuel pump! I didn't know that, and I admit that I am partially wrong. But, my statement of getting closer to 200+ flight is correct if you have one that counts by RPM and fly around at 1/2 throttle a lot. I was wondering why I got a lot more flights then what you were claiming. Your engine, there is no consumer control by the throttle stick.

Here is the return email from Arno at EvoJet:
Hi Dan,we have both:

23:HOUR-METER total running time of pump stored in the ECU

24:ENGINE type and serial number and revs counter total (in millions) stored in the ENGINE

BR

Arno
I'd agree that it should work of the basis of total revolutions - not time - but the current version does record running time and that is how JetCat specify the service interval. So, if you want to keep the warranty, that is what you have to use - and you will only get 150 flights.

Having said that I'd also - agree -with others on this thread - that most engines will go a LOT longer than this before they really need a service.

Wren specify 50 hrs even for the 44/45 size.
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Old 08-08-2017, 02:23 PM
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;o) I think some of this must be "fake news".......lol. Hope some of you get the chuckle I did.
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Old 08-08-2017, 03:27 PM
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This is interesting. Makes a person wonder how long you really can run a turbine before it actually "should" have a service call. The 25 hour mark seems more a PM type of thing. But I am sure there are reasons for it.
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Old 08-08-2017, 04:35 PM
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So? Are you building a jet sled for when the lake freezes? I don't think you get a lot of snow on that side of the lake?
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Old 08-09-2017, 05:09 AM
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HAHA! No jet sled for this guy. And yeah, where I am we get hit pretty hard sometimes!!
Doesn't help that I hate winter with a passion too! LOL!
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Old 08-09-2017, 05:48 AM
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Quote:
Originally Posted by RCFlyerDan View Post
APU's in Full scale jets are made for long term running at high throttle settings. Turbine Electric power units? Jets running at full power isn't the main reason engines fail. They can sit there and run at full power for thousand of hours. This is why planes are now allowed to fly across the oceans with two engines. What truly hurts a jet engine; is the initial start up heating, and acceleration of the engine, again, another high temperature of raw fuel being dumped into the burner can. High heat tends to warp things.

.
Not entirely true Dan. Airliner engines are only run at full power when absolutely neccesary, thats why the use of thrust derates for take off is the norm, particularly on the twins which have so much surplus power being capable of taking an engine failure at V1 even at max TOW.

Avoiding very high power settings considerably extends engine life, I believe the RB211 has spent upto 40,000hours on the wing !

AMT don't give a service interval (at least not on my Pegasus and Olympus manuals) but do suggest a regular check of bearing "feel" and for roughness.

A tip given to me along time ago by RR is that ANY deterioration in an engine will ALWAYS result in a rise in EGT, which is why I always use a GSU to check idling egt and an occasional full power EGT check . No change : all well, keep flying it !

I am currently running a PST 600R until, and if, it, fails to see what goes first, over 60 hours running and its still performs perfectly.

I recently had a PST 1300 checked at 40 hours, looked like new inside !

David.
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Old 08-09-2017, 12:53 PM
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Quote:
Originally Posted by David Gladwin View Post
Not entirely true Dan. Airliner engines are only run at full power when absolutely neccesary, thats why the use of thrust derates for take off is the norm, particularly on the twins which have so much surplus power being capable of taking an engine failure at V1 even at max TOW.

Avoiding very high power settings considerably extends engine life, I believe the RB211 has spent upto 40,000hours on the wing !

AMT don't give a service interval (at least not on my Pegasus and Olympus manuals) but do suggest a regular check of bearing "feel" and for roughness.

David.
Must be that "Fake News" again! In all seriousness though, I have been retired for 17 years out of the cockpit. And only had an opportunity to fly the older jets. For Fans, I have only flown the Garrett 731's. And, yes, they run a lot cooler at altitude. I am very aware of Reduced TO on the 72, and it had the old JT8's. The APU's on those were always screaming with the packs ON on a hot night. They did run at red line on temp in those wheel wells. Don't remember the numbers. though, nor on the JT's. I used to also fly RR Viper 522 on an old HS-125- 1A. We did run those at red line or you didn't make it to altitude for any kind of endurance of flight. I also remember the Garrett 331's on the Mu-2K at altitude ran hot. Of course the PT-6's didn't on the King Airs and Cheyennes. I know that jet engines aren't at full throttle until at altitude. This is due to the RPM's being more in the high 90's, and about temped out. Wasn't really talking about TO, and you are correct. Thank you.
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Old 08-09-2017, 02:08 PM
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Quote:
Originally Posted by RCFlyerDan View Post
Must be that "Fake News" again! In all seriousness though, I have been retired for 17 years out of the cockpit. And only had an opportunity to fly the older jets. For Fans, I have only flown the Garrett 731's. And, yes, they run a lot cooler at altitude. I am very aware of Reduced TO on the 72, and it had the old JT8's. The APU's on those were always screaming with the packs ON on a hot night. They did run at red line on temp in those wheel wells. Don't remember the numbers. though, nor on the JT's. I used to also fly RR Viper 522 on an old HS-125- 1A. We did run those at red line or you didn't make it to altitude for any kind of endurance of flight. I also remember the Garrett 331's on the Mu-2K at altitude ran hot. Of course the PT-6's didn't on the King Airs and Cheyennes. I know that jet engines aren't at full throttle until at altitude. This is due to the RPM's being more in the high 90's, and about temped out. Wasn't really talking about TO, and you are correct. Thank you.
Jet engines don't have a "full throttle". What they do have is a tradeoff between usage pattern and longevity/servicing costs. These days the guys at Rolls-Royce don't sell engines - they sell thrust. In fact they actually sell a thrust-usage profile. You tell them how much thrust you want, what the usage pattern will be etc and they quote a price. Different thrust levels will have different prices - but may well be fulfilled by exactly the same engine - the only difference being in the servicing requirements. Aero engines are designed on the assumption of a standard usage profile (takeoff, climb, high altitude cruise etc).

Engines for static use are designed differently. For example the engines used to provide power for oil rigs will be running constantly at "full" throttle - that being the maximum long term sustainable rpm. The engine can run at higher power levels if more fuel is pumped in - but it will not last as long.

I was told (by a guy from European Gas Turbines) of one instance where a mistake was made in the rig design and the specified engines did not have sufficient power. However, when the problem was discovered the cost of redesign and delayed production would have been very high. The cheapest solution? Fit the original engines, run them at "110%" and replace them with new ones every month!

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Old 08-10-2017, 09:50 AM
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We found the the Gas Turbines used for power generation on our platforms, running on produced platform gas, to be very reliable, the only fly in the ointment could be if the Platform had a production shutdown (The wells close in automatically).
The back-up system should seemlessly change the turbines over to diesel fuel, and worked on some Platforms better than others.

I once saw a Turbine, and the associated exhaust / heat exchange facilities totally destroyed when the system changed over to diesel, the ignition failed, and continued to pump diesel in to the hot Turbine, this turned to vapour, and some seconds later ignited, with the subsiquent explosion causing major damage. (It was found someone had by-passed a safety system during trouble shooting earlier in the day)
Sorry to go off topic a little

Alistair.

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Old 08-10-2017, 10:32 AM
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So for model gas turbine engines would running them full power for 5 - 8 mins reduce life?

Thx in advance
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Old 08-11-2017, 03:21 AM
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Quote:
Originally Posted by josecilurzo View Post
in time : AMT = ROLLS ROYCE !!
I saw some engines that runing perfect since 1996 without any service.
jose
Hi,
I wonder how many hour they have on each of them?

/Bo
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Old 08-11-2017, 04:51 AM
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Quote:
Originally Posted by Zeeb View Post
Behotecs are also 50 hours.
I have 26 hours on a Behotec 220 and now a $800 plus bearing service bill.
Rcpete
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Old 08-11-2017, 08:48 AM
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Quote:
Originally Posted by rcpete347 View Post
I have 26 hours on a Behotec 220 and now a $800 plus bearing service bill.
Rcpete
Guess you have had it longer then 2 years for the warranty to take care of it.

David G. Why do the AMT's last longer? Are the bearings stainless steel, titanium, or some other hard metal? Rather than ceramic?

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Old 08-12-2017, 11:13 PM
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sorry, Dan, double post see below!

Last edited by David Gladwin; 08-12-2017 at 11:22 PM.
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Old 08-12-2017, 11:18 PM
  #49
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I believe AMT engines use ceramic bearings, superior for such application, lighter and harder than steel. I will ask Bennie for confirmation.

AMTs are probably stronger built than most engines, and are not so highly stressed, even running at full power. As well as strong construction the internal flows probably result in lower turbine inlet temperatures, giving the NGVs and turbine wheel an easier life, too. That temperature is critical and RR allowed higher temps and thrusts with excellent reliability when they developed the single crystal turbine blade. (each blade on the wheel of a Trent produces 900 HP !)

I have always compared them, AMTs with the Rolls Royce RB211, (Now Trent) heavier than comparable engines but demonstrating incredible reliability.

That said, I believe one of the most important aspects of long bearing life is clinically clean fuel, Multiple filtrations through fine filters) and the optimisation of turbine life is minimising full throttle use, just as is done in airliner ops. ( my own civil engine experience is with RR Conways, RB211, P&W JT 8, CFM 56, GE CF6, only the old Conway ever failed on me, once, and on that occasion when using full power for take off, and all used de rates when possible as its the last few rpm % which creates the greatest stress and wear.

The one engine that did run at 100% in supersonic cruise, about 2.5 hours at Mach 2, was the RR Olympus 593 on Concorde, a truly brilliant engine!

David G.

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Old 08-13-2017, 04:54 AM
  #50
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Thank you David! Sounds like the AMT are derated for the r/c application? Maybe more oil nozzles pointed at the bearings? Or thicker material for the blades and burner can?

I only ever had two engine failures, and they weren't true engine failures, but shutting down due to components. Had the #2 on the 72 overheat and couldn't get it to cool in flight. Returned to departure airport, since we had maintenance there. The mechanics couldn't find anything wrong with it. I flew it the next night. The other older Capt's harassed me for shutting it down. Two weeks later, that engine dumped it's guts on the runway on take off. I was able to tell the Capt of that flight, "I told you there was something wrong with that engine". He was one of the one's that harassed me about it. The other was a PT6, and it was a shut down, due to an uncontrollable fuel controller. I remember on the RR Viper 522's it was fill the oil and check the fuel. Then, Garrett came out with the conversion for the Hawker. The 522's took a dump on the market. We cancelled our Power by the Hour and bought a mid time engine for about $30K for the next hot section or over haul and just junk the engine that came off of the Hawker. Not sure what a hot section cost in the early 80's, but it was up over $100-200K. You probably know David. We never used it, and sold it with the jet. I think this is why my attitude on these is after warranty to just run them until they quit or need service, rather then do the 25 hours on it.

I love the Concorde too. I want to build the kit after I finish a Rauch B727 that I just started building. Not sure why the airliners aren't popular here in the States. Guess it is because you have to actually build it.

Bräuer Flugmodellbau - Aérospatiale-BAC Concorde

To the OP, not sure if we have helped you on your decision. But not knowing your application, since you are going to run it for hours at a time, I think I would buy two that are warrantied by one of the "Life Time" engine manufacturers, and swap them out as they need the 25 hour service. This is provided that they will warranty it for your application.

Time to go to the field and fly!! Have a good Sunday!
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