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  #1  
Old 08-03-2021, 12:13 PM
moespeeds moespeeds is offline
 
Join Date: Apr 2021
Location: west berlin
Posts: 64
Default Question about mounting a Whirlwind RV200 prop on my IO360 - did I do it wrong?

Hey guys,

Saturday a friend helped me mount the WW RV200 prop back on my RV8 with a Mattituck TMX 300 IO360 engine. I had sent the prop out to WW for an OH, and got it back last week.

The friend who helped me was a very experienced pilot and mechanic, but not an A&P.

When we were setting up, he commented that my mounting flange did not have the larger locating lug to index the prop, and it looked to him like it could be clocked in any orientation. We mounted it the way it was when I purchased the airplane last month using photos I had taken before it came off. It had run in that orientation for 300+ hours.

After mounting it hand tight, he told me that the orientation was wrong, as TDC for cyl #1 put the prop about 2/7 o'clock, and he thought it should be 10/5 o'clock, which agrees with what WW says in the manual. We changed it to 10/5 and everything seemed to go on just fine.

On my way home I spoke to another friend of mine who happens to be an A&P, but is a massive "know it all" who regularly speaks as an expert on things he knows nothing about. He was adamant that we had mounted it wrong, and that the mounting flange had 4 drive lugs and 2 flush "indexing" lugs. He's claiming that we had pressed the drive lugs back because of how we mounted it, and the propeller was sure to go into harmonic vibration and fail. He even knew specifically where it would fail, telling me 2" would come off of each tip. Mind you, he has never seen my airplane, or even photos of this setup, and he only works on Mooneys.

So my question: Is there any validity to this, and if so, is there a way I can check on this with the prop mounted? I can provide photos in a couple hours when I get to the hangar.

I'm perfectly willing to pull it back off if I did it wrong.

TIA
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Moe Colontonio
Cherry Hill, NJ
RV-8 N495T

Last edited by moespeeds : 08-03-2021 at 12:16 PM.
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  #2  
Old 08-03-2021, 12:53 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 6,537
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There is one lug that is about .020" larger than the others and is called the index lug. However, this is for indexing the flywheel and NOT the prop. One flywheel hole is .020" larger and the flywheel can only go on one way; This ensures that the TDC markings on the flywheel are accurate. The larger diameter only protrudes about an 1/8" past the crank flange and doesn't extend past the flywheel (it steps back down after 1/8" if it is a long lug, though it is typically a short lug). Probably best to follow the prop manufacturers guidance for clocking on your engine, but is not intended to follow the index lug. All the bores in the prob hub are the same ID; No indexing.

some props have bores for all six lugs and some only have 4 or 5 enlarged bores. In the case of the later, you need to ensure there is a short lug (doesn't protrude past the flywheel) in the location without the enlarged bore. For most engines, there are 4 long lugs (set up in a rectangular pattern) and two short ones (don't protrude past flywheel)

If you think the A&P may be correct, look at the back side of the crank flange. If any of the lug flanges are pushed back from the crank flange, he was correct. It would seem unlikely that you could get it wrong without realizing it; Prop hub wouldn't sit parallel to the flange prior to tightening. Prop lugs are an interference fit with the crank flange.

Larry
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Last edited by lr172 : 08-03-2021 at 01:20 PM.
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  #3  
Old 08-03-2021, 01:00 PM
scsmith scsmith is offline
 
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Location: Ashland, OR
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I think I can help here.

First, your identification of orientation is a little ambiguous because the clock positions are not given 6 hr apart. Example, it should be 5/11 or 4/10, not 5/10. (unless your prop is bent )

The idea of a harmonic problem causing a blade tip to break may have some truth to it, but it is totally dependent on the prop design, construction, and operating environment. So just because a metal prop on a Mooney might have a harmonics problem if clocked a certain way or run at a certain RPM does not mean that a WW200RV prop would under the same conditions.

It seems very unlikely that you would install the prop and force the indexing bushing out while tightening the bolts. For one thing, the prop would try to 'tilt' rather than pull on straight. It is kind of a pain that the limited travel of the bolts in the hub prevent you from fully seating the prop against the flange prior to bolt tightening, you have to progressively tighten as the prop is drawn onto the crank flange. But if you had it mis-indexed and pushed the indexing bushing out, you would see that by looking at the back of the flange.

It may be that the builder removed the indexing bushing or the long bushings. People often experiment with different propeller clocking positions, and that would be facilitated by removing the larger bushing. If you look in an engine parts manual for your model prop, you will see the bushing part numbers and locations. Here is an example from my parts manual for the IO-360-A1A:

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On my engine, depicted in the far right, there are two short bushings (the index bushing and the one opposite it) and four long bushings. So the index bushing does not extend beyond the flywheel as Larry mentioned above. But you can also see that some engines have all long bushings, such as depicted in the middle flange picture in my manual, for the IO-360-B2F and -B4A. In that case, the indexing bushing would extend into the propeller hub. In the notes, not depicted in my picture here, it shows that the all-long bushing arrangement is specifically for a Sensenich prop.

If you in fact don't have an index bushing, or if none of your bushings are long enough to extend into the prop, you can look at the prop hub and see which holes are larger - so you know where the longer bushings and/or index bushing would go, and you can look at the parts manual to see where the long bushings and index bushing would be located on the crank (they all seem to have the index bushing at 10-o'clock when crank pin #1 is up (note that is not TDC for #1, since the cylinders are horizontal) With cyl #1 at TDC, it looks like the indexing bushing would be at 7 o'clock.

Finally, my recollection is that on my engine, TDC#1 puts the prop at 5/11 o'clock.

Hope that helps.
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RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet" Flying since Sept. 2009
Hobbs 700
also
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Last edited by scsmith : 08-03-2021 at 01:21 PM.
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  #4  
Old 08-03-2021, 01:13 PM
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airguy airguy is offline
 
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Quote:
Originally Posted by scsmith View Post

Finally, my recollection is that on my engine, TDC#1 puts the prop at 5/11 o'clock.

Hope that helps.
The only ambiguity here, and I've seen it many times before, is which direction you are viewing the prop (from the front, or from the cockpit) to determine the 5/11 clocking.
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Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
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  #5  
Old 08-03-2021, 01:18 PM
scsmith scsmith is offline
 
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Quote:
Originally Posted by airguy View Post
The only ambiguity here, and I've seen it many times before, is which direction you are viewing the prop (from the front, or from the cockpit) to determine the 5/11 clocking.
Yes, that's true. In this context, I am describing as looking at the prop and engine flange from the front.
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Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet" Flying since Sept. 2009
Hobbs 700
also
1/4 share in 1959 C-182B (tow plane)
LS6-15/18W sailplane SOLD
bought my old LS6-A back!!
VAF donation Dec 2020
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  #6  
Old 08-03-2021, 02:38 PM
Ralph Inkster Ralph Inkster is offline
 
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Lycoming doesn't make it easy to understand the bushing locations either.

search >> 'Lycoming Service Instruction 1098G'

(below the 2 flange diagrams) they note that the view is from the front of the engine looking aft.

The Type 2 prop flange is the left one depicted in the bulletin. Note that as drawn, the flange is at the 90 degree BTDC location. I read the 'No. 1 Crankpin' location as where the #1 connecting rod bearing as referenced in the diagram. So to view the flange in the #1 TDC location (as most people would normally describe prop clocking) - you have to rotate the diagram 90 degrees counter clockwise...

Per the document, the 4 longer bushings should be in locations A,B,D,E. Location F would be the 'reference bushing' (shorter & wider) and location C should be a short narrow bushing. Accordingly the prop should mount with the blades lined up through bushings C & F(assuming your prop flange holes are arranged that way). Now, rotating the diagram 90 degree counter clockwise to get the flange to #1 TDC, the prop should hang at 1/7 clocking if I read Lycomings SI correctly.

Sorry, this post would make a lot more sense if I could get the picture attachment to work, not happening for me today...
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Last edited by Ralph Inkster : 08-03-2021 at 02:46 PM.
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  #7  
Old 08-03-2021, 05:56 PM
moespeeds moespeeds is offline
 
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Sorry guys, I dictated all that while driving. Prop sits at 11/5 when viewed from the front, with #1 at TDC. I ran a scope behind the hub, and all bushings are tight to the flange.
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  #8  
Old 08-04-2021, 06:51 AM
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DanH DanH is offline
 
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Quote:
Originally Posted by Ralph Inkster View Post
Lycoming doesn't make it easy to understand the bushing locations either.....to view the flange in the #1 TDC location (as most people would normally describe prop clocking) - you have to rotate the diagram 90 degrees counter clockwise...
Ralph makes a good point. No one actually positions the crank as depicted in the SI. In the field we reference TDC, not halfway down the stroke.

SI illustration on the left, reality on the right.
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  #9  
Old 08-04-2021, 07:08 AM
moespeeds moespeeds is offline
 
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Ok so according to the above diagram, I've got the prop at B/E.

My question is, did I do it correctly?
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  #10  
Old 08-04-2021, 07:39 AM
Freemasm Freemasm is offline
 
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Location: Orlando
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Default Side Question for you knowledgeable types

Have heard that initially the 10 to 11-ish clocking was chosen for gaining the proper mechanical advantage for hand propping; harmonics and other considerations aside. The way things tended to develop, it's believable.

Any known truth to this? Sorry for the drift.
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