What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Question about mounting a Whirlwind RV200 prop on my IO360 - did I do it wrong?

moespeeds

Well Known Member
Friend
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
 
Last edited:
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
 
Last edited:
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:

Screen Shot 2021-08-03 at 11.55.01 AM.png

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.
 
Last edited:
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.
 
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.
 
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...
 
Last edited:
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.
 

Attachments

  • PXL_20210801_005646730.jpg
    PXL_20210801_005646730.jpg
    324.5 KB · Views: 237
  • 20210803181420297.jpg
    20210803181420297.jpg
    166.7 KB · Views: 257
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.
-
 

Attachments

  • Flange Drawings.jpg
    Flange Drawings.jpg
    60 KB · Views: 273
Ok so according to the above diagram, I've got the prop at B/E.

My question is, did I do it correctly?
 
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.
 
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).

Supposedly the flywheel can only go on one way...

One of those interesting little stories out of OSH this year. A fellow had a mag failure. New mag is installed and timed in the usual manner...and the engine runs awful. Much head scratching ensues. A smart guy pulls a plug to check that TDC is actually TDC...and it's not.

Reconstructing, the timing was set at the manufacturer before the initial run-in. Engine was subsequently installed and flown a few hundred hours, without any further timing check by the builder. However, somewhere in the process the builder had removed the flywheel, and re-installed it 60 degrees off. Fast forward to OSH; when timed to the TDC mark on the incorrectly installed flywheel, it didn't run well at all at about 85 degrees of advance.

The specified diameter for the flywheel index bushing 0.0313" larger than the other bushings. The one oversize hole in the flywheel is marked with a "O" symbol so the bushing and hole can be easily paired. However, if a fella puts a small hole over the big bushing and cranks down on the prop bolts, it doesn't back the bushing out of the engine flange. It just enlarges the flywheel hole.

If it don't fit, we'll make it fit ;)
.
 

Attachments

  • Enlarged Hole.jpg
    Enlarged Hole.jpg
    51.6 KB · Views: 128
  • Enlarged Hole 2.jpg
    Enlarged Hole 2.jpg
    52.3 KB · Views: 121
This is exactly what WW states in their documentation.

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.
 
Ok so according to the above diagram, I've got the prop at B/E.

My question is, did I do it correctly?

No. Or maybe it doesn't matter.

A question....the Whirlwind does not have one small diameter hole, like a Hartzell? With the small hole, the Hartzell only goes on with the correct orientation, as below. Given you report no bushings pushed out, the Whirlwind must not have the small indexing hole.
 

Attachments

  • ScreenHunter_882 Aug. 04 08.34.jpg
    ScreenHunter_882 Aug. 04 08.34.jpg
    73.1 KB · Views: 143
  • Crankpin Orientation wProp.jpg
    Crankpin Orientation wProp.jpg
    35.6 KB · Views: 123
I have a WW 200RV bolted to an ECi IO-360 assembled by a reputable engine shop. The only way it would bolt on is with the prop 12-6 at TDC. It's been flying for about 350 hours or so and nothing has fallen off yet. I've been flying along fat dumb and happy until I read this thread. Now I'm fat dumb and curious. Has 12-6 caused any issues I should know about? I won't be hand propping so that's not an issue with me. Thanks!
 
Maybe prop clocking is not as much of an issue for WW props. With the light weight (mass) blades, position may not be as critical - only WW would be able to answer this question.

First paragraph on 1098G reads "...When replacing flange bushings, it is extremely important that the correct size and location be observed, If a propeller is not indexed correctly, excessive propeller blade stresses may result."

Maybe Hartzell prop blades have enough weight (mass) to be concerned about power pulses/torque stresses etc. that Hartzell indexes their prop flanges & WW might not.

Maybe someone who has contacts with the prop manufacturers could call them & get the mfg official view?? Hartzell, WW, MT, & who ever else. This would be a service to the group with real information.
 
Last edited:
Here's a clue from the Whirlwind Aviation instructions for the RV series props.

Read the note carefully. They suggest mounting with the upper blade at 10 o'clock, but they do not reference TDC.

Instead, reading further, it states "...the approximate 7 o'clock position where the magneto snaps and the ignition fires". By extension, that statement tells us the relationship between TDC and prop position, given the impulse coupling would trip around TDC. The suggested clocking would be just like the Hartzell two-blade.

I say "suggested" because the Hartzell will only go on one way (the small hole in the hub can only be over a flange bushing), but if the Whirlwind has six holes with clearance for bushings, it will go on three ways.
 

Attachments

  • Capture.JPG
    Capture.JPG
    44.9 KB · Views: 152
I have a WW 200RV bolted to an ECi IO-360 assembled by a reputable engine shop. The only way it would bolt on is with the prop 12-6 at TDC. It's been flying for about 350 hours or so and nothing has fallen off yet. I've been flying along fat dumb and happy until I read this thread. Now I'm fat dumb and curious. Has 12-6 caused any issues I should know about? I won't be hand propping so that's not an issue with me. Thanks!

Kinda what Ralph said and a little more. Four bangers don't have any combustion event overlap. This makes for strong energy impulses = not so smooth ops. This is a known problem where blade metal fatigue can be an issue. CW'd cranks help but are not a cure-all. The composite blade material should be a plus.

Find out why your clocking is off. Stick with the OEM recommendations. Stay safe.
 
Jay at WW told me TDC #1, blade at around 10 O'Clock. That's where I got that from. I have a call into him today to clarify. Pisses me off, because the way it originally was mounted looks like it was correct, but we changed that based on the phone convo with him.

Here's a clue from the Whirlwind Aviation instructions for the RV series props.

Read the note carefully. They suggest mounting with the upper blade at 10 o'clock, but they do not reference TDC.

Instead, reading further, it states "...the approximate 7 o'clock position where the magneto snaps and the ignition fires". By extension, that statement tells us the relationship between TDC and prop position, given the impulse coupling would trip around TDC. The suggested clocking would be just like the Hartzell two-blade.

I say "suggested" because the Hartzell will only go on one way (the small hole in the hub can only be over a flange bushing), but if the Whirlwind has six holes with clearance for bushings, it will go on three ways.
 
Moe, I just did an oil change today so I checked. My WW200RV prop on my IO360 is exactly vertical when the TDC mark on the flywheel is lined up with the case split. I’m pretty sure mine was drilled so that it would only go on one way.

Note that this is consistent with what NLPete said above.

Note also that this causes the engine to stop with the prop horizontal (3--9 position) which is consistent with what DSmith said the next post.
 
Last edited:
About 12 years ago when I installed my WW200RV on my Mattituck TMX IOF-360 WW told me clocking didn't matter. My engine stops with the blades at 3 and 9 o'clock. I find that convenient when removing the cowl. It has about 400 hours and is smooth as silk and the blade tips have not come flying off! Yes I know clocking doesn't have much to do with smoothness.
 
I'm at my hangar now, and I verified that the engine is at TDC on the compression stroke.

Prop is at 12/6. Mag clicks just as it swings through 6.

The mags are properly timed, we verified that. Flywheel TDC mark matches the little starter hole.
 

Attachments

  • PXL_20210807_185035884.jpg
    PXL_20210807_185035884.jpg
    398.6 KB · Views: 103
  • PXL_20210807_185050394.jpg
    PXL_20210807_185050394.jpg
    319.9 KB · Views: 140
Prop flange bushings

Reviving this thread.
I am planning to install a WW 300-RV prop on my 7A with IO-360-M1B.
WW plans page 7 depict the drive lugs extending past the flywheel surface .180"-.200". Mine are .140"
Has anyone delt with this recently?
What was the solution?
Screenshot_20220421-114221_Yahoo Mail.jpg
 
Back
Top