dougmeyer
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posted October 19, 2010 08:03 PM
 Edited By: dougmeyer on 20 Oct 2010 04:04
O.T. Worked on a new engine today!
My first Jet. Well Turboprop. It's a 750 hp Pratt&Whitney PT6-135. Thought you would like to see some of the guts.
The plane I'm flying needed a little work so we decided "to do it ourselves". Needed a few special tools, but it only took a couple hours to get the compressor turbine on the table. Interesting stuff! We send out the turbine wheel for some new blades and get the injectors cleaned. The blades look like we've been runnin' it a little hard (hot), but we like to fly it as fast as we can ('cause that's what it's for! ).
Each blade on the turbine wheel is replaceable separately. These are VERY expensive.
The damage is on the blade tips.
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entropy
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posted October 20, 2010 01:52 AM
hey Doug, thanks for posting the turbine pix, I LOVE that stuff!
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Y2KZX12R
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posted October 20, 2010 03:52 AM
Edited By: Y2KZX12R on 20 Oct 2010 11:53
Awsome Doug!
Are those root fed air cooled blades? Is the recessed area near the tip, where the cooling air exits the blade? If so is that a hot spot?
It looks like the tip erosion isn't uniform on all tips. Is there a rime or reason for this? Is that typical wear?
Does the leading edge get worn and change the airfoils efficiency?
How many hours on these blades?
Hows the stator look? Is that equally worn?
Is my plane almost done yet? I need it by Halloween! Did you get me check?
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WRECKSHOP
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posted October 20, 2010 04:51 AM
Wow. Nice.
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TRNorBRN6001
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posted October 20, 2010 05:39 AM
Cool pics, any noticeable performance loss?
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aliveagain
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posted October 20, 2010 08:36 AM
my first thought was that it probably was going in a crown vic and used for towing.
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TRNorBRN6001
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posted October 20, 2010 08:56 AM
That would make the old Crown Vic ready for a run on the salt.
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entropy
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posted October 20, 2010 09:20 AM
quote:
my first thought was that it probably was going in a crown vic and used for towing.
Pete
GOOD ONE!!!!!!
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entropy
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posted October 20, 2010 09:23 AM
Edited By: entropy on 20 Oct 2010 17:28
a couple guys i know work for Hickham here in Houston.
Hickham repairs/fabricates parts for turbomachinery.
I'm gonna snip that blade damage and see what they say 
(you Texas Mile folk know these 2 daredevils also)
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tricktom1
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posted October 20, 2010 09:35 AM
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entropy
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posted October 20, 2010 09:40 AM
"This should not be flown due to tip rubs and a loss of coating.
It should be donated to me immediately for land speed research. "
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dougmeyer
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posted October 20, 2010 10:32 AM
That would be interesting, but then I couldn't fly it around pretending to be a rich guy. Yup loss of coating and tip erosion, no evidence of tip rubbing on the stator. No Jim, nothing noticeable from the left seat. Still made rated power, smooth as silk. Truth is, it probably would go another 500 hours like that. Not cooled blades, they're only about 1" long, little fellers. That turbine spins at about 31,500 rpm at max power. That is premature wear, with only about 500 hours on the engine. We don't know why yet. It's been operated at max power a lot, but always within limits. Experts tell me that it's "heat damage".
There's always more cool stuff to learn!
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entropy
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posted October 20, 2010 11:31 AM
doug
at the texas mile you will have the opportunity to grill a couple guys about this stuff, could you get more pix, incl stator?
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dougmeyer
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posted October 20, 2010 05:30 PM
Got 'em on the computer box, right here in my hand.
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aliveagain
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posted October 20, 2010 05:45 PM
How much would a power plant like that cost?
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whitehendrix
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posted October 20, 2010 11:27 PM
aliveagain.. you don't even want to know.. haha.. they're stupid expensive.
Doug! great pics! definitely odd the tip erosion is not uniform. but obviously you suspected something with the injectors being you sent them out. could have been unequal flamefront propagation had an injector not been spraying/atomizing correctly.
love turbine engines.
hope to pick up a boeing APU i've had my eyes on for a few years.. just haven't had the money. would be alot of fun in a .. something. bike maybe?
haha
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Ricksgsxr
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posted October 21, 2010 09:50 AM
Doug-
Lets assume stock hp is not enough how hard is it to modify this motor to make more mojo short of buying a differnt plane?
TIA
Rick
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Y2KZX12R
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posted October 21, 2010 07:06 PM
Edited By: Y2KZX12R on 22 Oct 2010 03:07
I had a chance to buy a running R4360 about 8 years ago for $5500. It was on a test stand.
When I told my wife about it she wanted to know what I would do with it.
I told her I was just going to bolt it down to the garage floor and start it up at parties for everyone and rev it up and let it make a lot of noise.
She wasn't impressed and gave me that look...... I was serious and she knew it. But I never bought it. I still kid her about it quite often.
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lowflyer
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posted October 22, 2010 06:15 AM
Doug, While it is apart, be sure to check each probe on the ITT harness. The gauge averages the temps, and if one or more is open or damaged, it lowers the average. If you have seen ITT's seem to get cooler over time at the same torque, that could be the cause. The reality is that the ITT's are higher, and the damage you are seeing is consistent with what I have seen in the past. In other words, Been There, Done That!
Don
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whitehendrix
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posted October 23, 2010 07:11 AM
Jim you shoulda put your foot down and bought it!!! haha
i still know where that Boeing APU is at. it still calls my name......
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ill never own a busa unless
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ill sell it -KZScott
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dougmeyer
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posted November 08, 2010 08:20 PM
Got the PT6 back together and flew it today. Wow what a difference! Silky smooth, better response.
LowFlyer Don had it nailed.. Here's what happened. Somewhere before I started flying it, this engine experienced what is known as a "hot start". This is when the pilot introduces the fuel before the engine is spinning fast enough. The usual cause of that is a low battery and an impatient pilot. The fuel lights, but there isn't enough airflow to keep the flame traveling and within certain heat limits like less than 800 C. (1472 F) and maybe up to 1000 C (1800F). The flame just cooks the turbine blades until the flow goes up and the temps come down. What also happens is that the thermocouples over-temp and can melt. See the little drip" melted into the thermocouple on my finger below? That's the melted tip of the tc. The problem is that there are 6 or 8 of those and they average their temp to the instruments. The bad one brings down the average and you then operate the engine hotter than you think. The hi temp erodes the blades then you've got to replace them.
The picture below is the rebuilt turbine wheel with the refurbished blades and the refurbished burner can. There are 58 of those blades and they cost about $700 each (new ones are more than a grand each). Yes, you did the math right......this little rebuild cost more than $60,000.
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Y2KZX12R
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posted November 09, 2010 07:51 AM
Ouch, $60,000 !!!
Gee a new set of zx14 exhaust valves doesn't seem so bad now.
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2000redrocket
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posted November 09, 2010 04:50 PM
wow doug. have not needed to think about turbins for a long time.
is that a annular combuster?
i was thinking the t5.4 got too high no matter what the guages were saying.
we were automated on start so the only hot start was something broke.
the only days we could be max power and good t5.4 temps with less than 100% pla was winter and the t5.4 had plenty of room those days.
sorry for the needed rebuild. that sucks epcecially on your bill.
i condemed out one turbin due to tip clang but the gov took that bill. we ended up reblading it.
i would love to work on them for a living again. ohwell
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zxboy
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posted November 09, 2010 07:37 PM
Doug.............
What airframe is that sitting in ??
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dougmeyer
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posted November 10, 2010 10:38 AM
Edited By: dougmeyer on 10 Nov 2010 18:40
Yeah, Jim it's a different world for sure. That was 60K for the parts. We did the R&R in house, and paid an expert to walk us through the assy. (less than 8hrs)
Annular combuster, yep. Your assesment is correct but the PT6 only has one PT wheel. What were you working on, Red?
ZXboy
It's the Lancair Evolution that I fly. The first prototype of the 30 sold. 6 are flying. It looks like this:
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