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O-290-G Prop Flange Reinforcement Plate

Steve H

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Does anyone have a O-290-G prop flange reinforcement plate laying around in your boxes of old parts? It's the plate that was formed to fit exactly on the back side of the flange and it's taper down the crankshaft. The purpose of the part was to add to the strength of the flange and also "insure" the propeller stayed with the engine if the flange broke.

I'd like to purchase one if available. I've had a want ad on Barnstormers for a month without any responses.

Thanks.

Steve H
 

EAABipe40FF

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It is actually 2-piece.

FWIW I suspect the cracked/broken flanges were likely caused mostly by the severely cut down and twisted propellers used on the fast airplanes like the Tailwind etc. If you use a full length metal prop like used on Pipers with the O235 & O290 or a wood prop you will probably have no trouble. After all the O290G crank flange is the O235 flange. Some have suggested that the O290G flange was hot heat treated, I don't know.

Of coarse aerobatics are another ball game, even standard "holy" O320 flanges are not immune.

Hope you find one. I put one on the prototype Spezio I once owned. The fit was very close but not perfect. I've wondered if a less than absolutely perfect fit might make it worse?

Jack
 

Steve H

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Thanks Jack. I've heard that aerobatics were the killers on the G flange. I was given a Stits SA-3A Playboy restoration project with a converted -G and a second one for parts. I'm thinking about using the -D that came with the Duster (bad cam/cylinders), and the 2 -Gs to come up with a good engine without a lot of expense. I know, airplane engine and expense are mutually inclusive, but it's worth a try. I'd like to get both the playboy and my Tu-holer going with these engines. The Duster has a good/running -D in it so it's good to go. I'd be comfortable flying with the -G and no plate, but thought I'd see if I could find one. We'll see if anything turns up.
 

race38

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There are plans/drawings for it. I have it somewhere. I think it’s in the files section on the Tailwind forum also.
 

Morphewb

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The drawings are in one of the 4 or 5 ''How To'' books the EAA sold (maybe still does) in the old days.
 

Steve H

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Thanks Morph and Mark, I'll check these leads out!

Steve H
 

Dennis Flamini

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i think the 1/4" thick aluminum ring gear is a better reinforcement.
 

Steve H

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Dennis, one conversion discussion says that if the ring gear isn't used, to use a .250 spacer between the flange and the prop. This confirms that the ring gear is considered as a reinforcement.

Mark, I got Thorp's drawing of the reinforcement plate off the Tailwind forum. Thanks. I found the AS&S part number for the part (05-28600) but it isn't available via the web site. I'll give them a call to see if they have any.

Steve H
 

EAABipe40FF

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There are two issues. First is cracked flange leading to broken flange/crankshaft leading to lost propeller. Either the .250 AL spacer/ ring gear or the steel "reinforcement" plate "might" prevent the flange from cracking/failing. The advantage of the plate behind the flange it that if the crank does break it might keep the prop from leaving the engine? Indeed considering it's design covering the radius it is probable that it will hold things together. Front plate? If the flange fails completely the prop is still gone.

Both are at best band aids IMO. Hopefully you make it safely to the ground but the crankshaft is still junk and/or the propeller is gone.

For me I believe the question as to why the flange fails is more important? And again I bet it's caused by problematic shortened metal propellers which cause unknown damaging harmonics which in turn might cause blade failure as well as crankshaft issues. Of coarse aerobatics also stress the flange but ALL flanges are subject to this to a greater or lesser degree. I've seen several pictures of cracked flanges on both 320 and 360 CID Lycoming cranks. Even the thick solid flanges are not completely immune.

As I said before, I'm a skeptic as regards the rear plates since they do not have a perfect fit(at least mine didn't), I wondered if it might itself cause a stress?(not that the plates were incorrect but that maybe the flange rear radius were not all exactly the same?) I installed it to keep the prop on if the flange did fail. The original Tu-holer did have a too short 74DM shortened to 66" as I recall although at the time(1981) I didn't know that if shortened below 72" all bets were off. (That said the airplane flew over 900 hours with that prop. Tony flew it w/o the reinforcement). The .250 front plate, why not? Indeed maybe even make it out of steel?

Me? If I had a G flange, I'd want either a certified in spec. metal prop or one made out of wood. And a good balance would also be a good idea. Of coarse INSPECTION is always the most important operative word!

FWIW

Jack
 
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EAABipe40FF

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correction. i said,

" Some have suggested that the O290G flange was hot heat treated, I don't know."

Misspelling, make that "not" heat treated?
 

TFF1

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I believe the G crank was not nitrided. It did not need the toughness running a generator. I think the flange plate is a good idea. Every G engine I have seen with the G crank has had one; its been 40 years since the idea was developed, so I would want one. Could probably machine a nice one for not much; not as cheap as the stamped one. Its at the back side radius that sees the stress. The flange flexes and cracks the radius out. The flange might crack with it all, but once it gets to the radius, its all over. I would rather it come off clean, if it breaks. Not like the bitts hanging on are doing much good.
 

EAABipe40FF

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If not nitrided then maybe a good idea? And if not the slight mismatch in machining probably not as much worry(a worry maybe only in my imagination). A better and/or additional idea might be to have Lycoming nitride it?

Tom, you may have a better insight into the failure process. I was thinking the flange cracked starting the process. If the crack starts at the radius then the reinforcement plates are indeed a good idea.

If someone makes them, make several----a bunch.

I have a O320 crank in my O290G so not to worry. But I've been eyeing relatively cheap O290G's offered lately and might grab an extra? I'd simply run it with a wood prop.

Jack
 
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Lotahp1

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Steve...alittle off topic but let’s see some pics of your Tu-Holer! I love Spezios!
 

Steve H

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Lotahp1, I put them in the "NonBipe" section.

Steve H
 

TFF1

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I think any G not flown heavy aerobatics is fine. It is always a tough call when dealing with budget stuff. I know. My G engine has a 320 crank, but it was a little bit of a mess so it cost more than I was expecting to get this thing together. I have thought of a G plate on a 320 crank for extra protection if flying heavy aerobatics with a metal prop on an older crank. Can't see how it would hurt.
 

SHIPCHIEF

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I have an O-290 G engine with a reinforced crank flange. It came off a Thorp T-18. It's a pile of parts now.
I bought the engine as a core to tear down and learn about Lycoming engines. Bits have goneto the Aviation Highschool as training aids.
I used the accessory gear case to convert an IVO-360 vertical helicopter engine to fit my RV-8 when I realized I was never going to get comfortable behind my turbocharged Mazda Rotary.
The crank probably has too much corrosion to be flight worthy.
A word about O-290G cranks. I have a T-18 friend who has faithfully had two (2 each!) Insurance tear-downs for prop strikes.
Once, when lifting the tailwheel while painting, the T-18 got away from him and fell on it's nose. The second time he was taxiing on a grass strip and one tire fell into a ground squirrel hole. He was powering thru the grass at high idle, and when it nosed over it shot up a big shower of dirt and broke both wood prop blades off to about 1/2 diameter and stopped solid.
The inspections revealed No Crank Damage! In Both Cases.
My T-18 has a converted O-290G with an O-320 crank & rods. I really like one aspect of the O-290G: The solid tappet cam and the oil ditches that collect oil spray from the crank and direct it down the pushrod tubes to drool over the rocker arms and valve stems. I bought a New Old Stock case to make a modern conversion. So I'm looking for qualified parts to make an O-320G by boring the case spigots. GO-480 angle valve heads, EDIS MegaJolt ignition etc...
The Mazda and reduction gear are going on an Airosani (Snow Plane) I've started the mount & frame.
https://www.tetonvalleynews.net/new...cle_1fc92f26-fde9-11e7-9db7-dbc5111968ad.html
 

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