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  #1  
Old 02-26-2020, 05:49 PM
N546RV's Avatar
N546RV N546RV is offline
 
Join Date: Aug 2010
Location: Houston, TX
Posts: 879
Default Whirl Wind compatibility with IO-370/375

So this is just an informational post for anyone who might be interested in this information now or in the future.

In another post about the HRT props and James cowl, it was pointed out that WW now has wording on their site about how they no longer support the IO-370 and -375 engines. This is of interest to me since that's exactly the combination I've been planning on for my build.

Anyway, I reached out to them to try and find out the reasoning behind this decision, and got this reply today:

Quote:
Hello Mr. Clifton,

Yes, since [last summer] Whirl Wind Aviation has decided not to support the IO-370 and the IO-375 engines.

Because of higher torsional vibrations of the IO-370 and IO-375 engines there is a strong possibility that they will need more frequent tear down inspections due to blade grease leaks. The grease leaks are not a safety issue but just a nuisance for the owner and we will not be pro-rating early tear down fees on the props on -370 and -375’s.

Additionally, there could be premature wear of the blade bearing races, retainers and possibly even the hub sockets that could lead to earlier, higher maintenance costs.

We have no objective data defining if or when such things will happen. They may never, but we know based on our vibration studies of these engines that the possibility exists.
So, long story short, there's no "ticking time bomb" thing going on here, they just strongly suspect that longevity of their props will suffer in front of thee engines, and they won't be responsible for shorter overhaul/maintenance intervals resulting from this combination.

So just an FYI for anyone else considering this combination and wondering what's up.
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Last edited by N546RV : 02-26-2020 at 05:58 PM.
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  #2  
Old 02-26-2020, 08:52 PM
climberrn climberrn is offline
 
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Location: Carson City, NV
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Default

So, since composite props handle torsional vibrations better than aluminum, where does that leave you in the search for a prop? Has Hartzel given an opinion on that engine?
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  #3  
Old 02-26-2020, 10:26 PM
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N546RV N546RV is offline
 
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Default

I don't believe Hartzell has given any sort of opinion, though this is based on what I've read while doing generic WW vs Hartzell research and is far from extensive. I had the same thought about composite + vibration, but in this case it sounds like their concerns are related more to the hub design than the composite blades.

The way I figure it, I have a few choices:
  • Go with my original plan (370+WW 74HRT) and deal with whatever happens down the road. Doesn't seem like there's a safety-of-flight issue, but possibly some wallet pain
  • Stick with the 370 and go with the Hartzell composite prop. More expensive up front but general consensus seems to be that things might even out in the long run thanks to longer teardown intervals with the Hartzell.
  • Stick with the 74HRT but go to an angle valve 360. Also more expensive up front, but less than the Hartzell option. I'm currently working on evaluating possible effects of going with the heavier engine.
  • Go with a regular old 180-horse 360 and maybe a 200RV prop from WW

Right now I'm leaning towards options 2 & 3, dependent on what my W&B analysis yields. Probably slightly more towards #2.

I'd like to be flying by the end of this year, so I'm looking to try and place FWF orders around the time of SnF to hopefully take advantage of discounts. The clock is ticking...
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  #4  
Old 02-27-2020, 04:37 AM
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Capflyer Capflyer is offline
 
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Default

We were contacted by GT Propellers, an Italian company. They make composite blades and use Harzel hubs. No endorsement here, not enough info but perhaps another option to explore. The owner is an RV guy.
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  #5  
Old 02-27-2020, 05:05 AM
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Walt Walt is offline
 
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Cut/paste from Hartzell application guide:

Aircraft T.C./STC: Experimental
Engine Model: Titan 370
Power: 210 HP @ 2700 RPM
Propeller Model: HC-M2YR-1BFPX (M is extended hub)
Notes: Remove TC and PC markings from Hub
and Blades, and Remove S/N from Hub.
Placard/Restr: With counterweighted crankshaft and 9.6:1
(or less) compression ratio: no placards
Blade:
F7497*3X
F7497X

I spoke with Les Dowd at Hartzell and he had no concerns using the HC-C2YR-1BFP (available from Van's) with my IO-370 high comp CW crank with stock mags.
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RV7A built 2004, 1700+ hrs, New Titan IO-370, Bendix Mags
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Last edited by Walt : 02-27-2020 at 04:40 PM.
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  #6  
Old 02-27-2020, 06:41 AM
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N941WR N941WR is offline
 
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Location: SC
Posts: 12,665
Default

Any word on the 340?
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  #7  
Old 02-27-2020, 08:02 AM
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Mark Dickens Mark Dickens is offline
 
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Location: Collierville, TN (KFYE)
Posts: 1,358
Default

Quote:
Originally Posted by N546RV View Post
I don't believe Hartzell has given any sort of opinion, though this is based on what I've read while doing generic WW vs Hartzell research and is far from extensive. I had the same thought about composite + vibration, but in this case it sounds like their concerns are related more to the hub design than the composite blades.

The way I figure it, I have a few choices:
  • Go with my original plan (370+WW 74HRT) and deal with whatever happens down the road. Doesn't seem like there's a safety-of-flight issue, but possibly some wallet pain
  • Stick with the 370 and go with the Hartzell composite prop. More expensive up front but general consensus seems to be that things might even out in the long run thanks to longer teardown intervals with the Hartzell.
  • Stick with the 74HRT but go to an angle valve 360. Also more expensive up front, but less than the Hartzell option. I'm currently working on evaluating possible effects of going with the heavier engine.
  • Go with a regular old 180-horse 360 and maybe a 200RV prop from WW

Right now I'm leaning towards options 2 & 3, dependent on what my W&B analysis yields. Probably slightly more towards #2.

I'd like to be flying by the end of this year, so I'm looking to try and place FWF orders around the time of SnF to hopefully take advantage of discounts. The clock is ticking...
There's nothing wrong with IOX-370 and the 200RV prop. It's what I run. My engine supposedly puts out about 191hp.
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  #8  
Old 02-27-2020, 10:23 AM
clam clam is offline
 
Join Date: Oct 2005
Location: Lakeland, TN
Posts: 184
Default No measurable data leads to opinion

Since the manufacturer's response was...
"Quote:

Hello Mr. Clifton,

Yes, since [last summer] Whirl Wind Aviation has decided not to support the IO-370 and the IO-375 engines.

Because of higher torsional vibrations of the IO-370 and IO-375 engines there is a strong possibility that they will need more frequent tear down inspections due to blade grease leaks. The grease leaks are not a safety issue but just a nuisance for the owner and we will not be pro-rating early tear down fees on the props on -370 and -375s.

Additionally, there could be premature wear of the blade bearing races, retainers and possibly even the hub sockets that could lead to earlier, higher maintenance costs.

We have no objective data defining if or when such things will happen. They may never, but we know based on our vibration studies of these engines that the possibility exists. "

not sure how anyone can make a data-driven, fact-based determination. Certainly, the manufacturer isn't able or willing.

Sounds like you just have to use your research thus far and make the best decision you can.

I fly the WW200RV turned by an IOX-360 and all is good in 130 hours. Of course, this isn't the combination you're looking for, so maybe some folks with 370/375 & WW with hours nearing the overhaul schedule can chime in with their experience. I'm interested in hearing their experience.
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  #9  
Old 02-27-2020, 12:28 PM
CharlieL CharlieL is offline
 
Join Date: Nov 2013
Location: Harwinton, CT
Posts: 65
Default Been happy with the combo

I have a WW 74RV on an IO-375. No issues in 560 hours over 4 years. Very happy with the setup.
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  #10  
Old 02-27-2020, 04:13 PM
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DanH DanH is offline
 
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Location: 08A
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Default

You don't want to bet against the ticking time bomb when considering any prop selected without the benefit of a blade vibration survey.

When Les Dowd says he has no concerns about a specific engine/engine accessory/propeller combination (see Walt's post), it's because Hartzell outfitted a test subject with strain gauges and a many-channel telemetry transmitter, then flew a specific series of flight tests. MT does similar. Best I know, Whirlwind does not, and there have been serious blade root issues with some combinations.

Which brings us to the notion of composite blades negating vibration concerns. There is some truth, apparently based on blade fatigue comparison with aluminum blades. However, that's a narrow area; overall the statement is far too general. "Composite" describes a wide variety of materials and methods, and even if the blade itself is highly fatigue resistant, there can still be blade shank, blade retention, hub, flange, and crank issues.

Trust but verify....
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