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11-05-2018, 05:41 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by Timberwolf
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?
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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.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Last edited by DanH : 11-05-2018 at 05:44 AM.
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11-05-2018, 08:21 AM
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Join Date: Aug 2006
Location: boynton beach fl
Posts: 210
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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
__________________
Carl Bridges
RV7 N278RV
NOW FLYING
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11-05-2018, 12:14 PM
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Join Date: Jul 2013
Location: US
Posts: 2,251
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Quote:
Originally Posted by DanH
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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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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2019 Dues paid!
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11-06-2018, 11:46 AM
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Join Date: Aug 2006
Location: boynton beach fl
Posts: 210
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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.
__________________
Carl Bridges
RV7 N278RV
NOW FLYING
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11-06-2018, 04:08 PM
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Join Date: Aug 2006
Location: boynton beach fl
Posts: 210
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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?
__________________
Carl Bridges
RV7 N278RV
NOW FLYING
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11-06-2018, 08:24 PM
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Join Date: Mar 2005
Location: DVT Phoenix
Posts: 1,187
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Quote:
Originally Posted by turbosaaber
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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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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Larry
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11-06-2018, 09:01 PM
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Join Date: Sep 2005
Location: Maple Grove, MN
Posts: 2,333
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Quote:
Originally Posted by DanH
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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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.
__________________
Alex Peterson
RV6A N66AP 1700+ hours
KADC, Wadena, MN
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