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  #11  
Old 11-05-2018, 06:41 AM
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DanH DanH is offline
 
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Originally Posted by Timberwolf View Post
I had my back late crack recently and after looking at what was the root cause and allowing the backplate to flex, I discovered there were no screws in the front bulkhead. I cut out a new piece and riveted it in, along with adding fasteners to the front bulkhead and haven’t seen any further issues. I’m with Walt in that there’s thousands of these setups, what makes yours/mine so special when these issues are otherwise unheard of?
Screws in the front bulkhead are not an absolute requirement. However, without screws, zero clearance between the bulkhead flange and the inside of the spinner is a must.

The problem seems to take two forms. The flange angle may not precisely match the spinner, and/or the spinner does not fit tightly against the flange at all 360 degrees. With screws, the screw heads will not be perpendicular to the spinner surface, or they will be pulling the fiberglass in when tight. To check, just start a long screw in the flange nutplate and eyeball it for 90 degrees to the spinner. Now eyeball a tight screw; any surface depression?

I've been running a "screwless" spinner about 830 hours now. Rear bulkhead is flat 0.100 6061 with axial screws from the rear, through a fiberglass flange added to the spinner. There are no front bulkhead screws. To ensure zero freeplay at the front bulkhead flange, the inside of the fitted spinner was sanded to be sure it was smooth, then shot with a few coats of PVA release agent. The front bulkhead flange was roughed up with some 120 grit, and a bead of proseal was applied. The spinner was then installed with rear screws tight. After time for cure, the spinner was removed and the excess proseal was cut along the flange edges. What remains is just a thin band of sealant on the flange, formed in place, which ensures zero gap or angle mismatch.
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Last edited by DanH : 11-05-2018 at 06:44 AM.
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  #12  
Old 11-05-2018, 09:21 AM
turbosaaber turbosaaber is offline
 
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Default No screws in fwd bulkhead

Also I do have a depression in a section of the aft spinner as dan describes so perhaps I should redo backplate and add screws up front too
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  #13  
Old 11-05-2018, 01:14 PM
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RV7A Flyer RV7A Flyer is offline
 
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Quote:
Originally Posted by DanH View Post
I've been running a "screwless" spinner about 830 hours now. Rear bulkhead is flat 0.100 6061 with axial screws from the rear, through a fiberglass flange added to the spinner. There are no front bulkhead screws. To ensure zero freeplay at the front bulkhead flange, the inside of the fitted spinner was sanded to be sure it was smooth, then shot with a few coats of PVA release agent. The front bulkhead flange was roughed up with some 120 grit, and a bead of proseal was applied. The spinner was then installed with rear screws tight. After time for cure, the spinner was removed and the excess proseal was cut along the flange edges. What remains is just a thin band of sealant on the flange, formed in place, which ensures zero gap or angle mismatch.
Identical set-up, and no issues whatsoever. In fact, it's one of the parts of the build that I like most...600+ hours now, no problems. (Knock on wood).
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  #14  
Old 11-06-2018, 12:46 PM
turbosaaber turbosaaber is offline
 
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Default Possible prop

Well I just looked inside the spinner and to d a bunch of prop grease built up by the blade. It’s an A hub so looks like the hub will need to be changed at the least. Might be a time to upgrade to a BA or other prop.

Thank you all for your thoughts and advise.
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  #15  
Old 11-06-2018, 05:08 PM
turbosaaber turbosaaber is offline
 
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Default 7k overhaul

Just talked to the prop shop near my house. Switch to a suffix b hub and overhaul 7k. Prop was overhauled 5 years ago. With vans price of 8k for a BA why would anyone overhaul a prop?
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  #16  
Old 11-06-2018, 09:24 PM
Larco Larco is offline
 
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Originally Posted by turbosaaber View Post
Just talked to the prop shop near my house. Switch to a suffix b hub and overhaul 7k. Prop was overhauled 5 years ago. With vans price of 8k for a BA why would anyone overhaul a prop?
Agreed but will Vans sell you a second prop at that price? Assuming that you purchased the original one from them, It's been said that they will only sell one per project? let us know what they say. Larry
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  #17  
Old 11-06-2018, 09:58 PM
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RV8JD RV8JD is offline
 
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Quote:
Originally Posted by turbosaaber View Post
Just talked to the prop shop near my house. Switch to a suffix b hub and overhaul 7k. Prop was overhauled 5 years ago. With vans price of 8k for a BA why would anyone overhaul a prop?
Quote:
Originally Posted by Larco View Post
Agreed but will Vans sell you a second prop at that price? Assuming that you purchased the original one from them, It's been said that they will only sell one per project? let us know what they say. Larry
I looked into this about a year ago for my previous RV-8. It had a Hartzell HC-C2YK-1BF/F7666A-2 C/S prop that was purchased against its Builder Number. I wanted to purchase a new Hartzell HC-C2YR-1BFP/F7497 (Blended Airfoil) C/S prop to replace the old one. Van's said that since it is a different Hartzell prop, Hartzell would allow the purchase at the Van's price.

As a side note, a new Lycoming engine was a little bit different. When I contacted Van's about a new Lycoming engine, they initially said no, only one Lycoming engine purchase per Builder Number, even if the new engine was different (O-360-A1A to IO-360-M1B). I explained that the original engine had about 1900 Tach hours on it and I wanted to replace it with a new engine. Van's talked to Lycoming and Lycoming gave me a call. I explained the situation, that the original engine was runout and I wanted to replace it with a new Lyc, and I was not planning on reselling the new engine. Lycoming thought about it and said that under the circumstances, I could purchase a new Lycoming through Van's at the discounted Van's price as long as I returned the original engine to Lycoming for a core credit.

In the end, a newer RV-8 came up for sale and I purchased it instead of putting a new engine & prop on my previous -8.
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Last edited by RV8JD : 11-06-2018 at 10:37 PM.
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  #18  
Old 11-06-2018, 10:01 PM
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AlexPeterson AlexPeterson is offline
 
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Quote:
Originally Posted by DanH View Post
Screws in the front bulkhead are not an absolute requirement. However, without screws, zero clearance between the bulkhead flange and the inside of the spinner is a must.

The problem seems to take two forms. The flange angle may not precisely match the spinner, and/or the spinner does not fit tightly against the flange at all 360 degrees. With screws, the screw heads will not be perpendicular to the spinner surface, or they will be pulling the fiberglass in when tight. To check, just start a long screw in the flange nutplate and eyeball it for 90 degrees to the spinner. Now eyeball a tight screw; any surface depression?

I've been running a "screwless" spinner about 830 hours now. Rear bulkhead is flat 0.100 6061 with axial screws from the rear, through a fiberglass flange added to the spinner. There are no front bulkhead screws. To ensure zero freeplay at the front bulkhead flange, the inside of the fitted spinner was sanded to be sure it was smooth, then shot with a few coats of PVA release agent. The front bulkhead flange was roughed up with some 120 grit, and a bead of proseal was applied. The spinner was then installed with rear screws tight. After time for cure, the spinner was removed and the excess proseal was cut along the flange edges. What remains is just a thin band of sealant on the flange, formed in place, which ensures zero gap or angle mismatch.
Until you spin it up.... I wonder how much the diameter of the spinner at that point grows at 2400 rpm? Probably doesn't matter, just wondering. There might be air in that gap when spun up.
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