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06-18-2015, 07:14 AM
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Join Date: May 2014
Location: Savannah
Posts: 806
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Quote:
Originally Posted by Brantel
The last spinner looks like it has the screws much closer to the cut out than the OP spinner. Could that be the root cause of the tear?
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Looks like the ED for that last screw was pretty big to me as well. Having excess ED is much preferred than not enough on almost all structure, but in this case it may have been the cause of the crack due to centrifiugal force load on the unsupported edge of the propeller cut out.
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Mike Hammond
A&P IA PPL ASEL
RV-14A kit S/N 140170
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06-18-2015, 07:18 AM
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Join Date: Oct 2009
Location: Victoria, BC, Canada
Posts: 3,932
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Quote:
Originally Posted by Brantel
The last spinner looks like it has the screws much closer to the cut out than the OP spinner. Could that be the root cause of the tear?
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That was my first thought when I saw it. The extra distance near the opening wasn't supported, it looks like about an inch or more long? The second installation photo shows the last screw very close to the edge of the opening, which gives better support, and the filler piece behind the blade will help support it as well.
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Rob Prior
1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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06-18-2015, 08:56 AM
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Join Date: Aug 2008
Location: West Virginia
Posts: 28
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Quote:
Originally Posted by Vern
Mine did that also so I went back to FG
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Please tell me it's not a Cummins spinner. We just had a FG spinner by Jerry Herrold come apart, and we're replacing it with the Cummins. Cummins does direct that the first screw be placed 3/8" from the prop cutout. Hope it works. As you know, or soon will, it's a large PITA to go thru spinner replacement, especially as the debris from the old spinner scored the prop just a bit.
Good luck on the replacement.
Cheers,
Chip
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06-18-2015, 10:22 AM
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Join Date: Jan 2007
Location: Mount Vernon, IN
Posts: 1,270
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What Axel said seems most likely.
Use tape, if needed, to shim up any gaps in the fitment between the spinner and the spinner backplate. If the fit isn't NICE AND SNUG, you're doing it wrong. You should have to bump the spinner down into place with your hand when installing it.
Many use masking tape. I've used the green painter's tape that doesn't dry out like regular masking tape. Keep the tape evenly distributed all the way around the backplate with no lumps or gaps.
If it takes more than 2 or 3 layers of tape, maybe you should reconsider the fit.
Others please chime in if I've misspoke here!
YMMV!!!!
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Vince Frazier
www.f1aircraft.com
F1 Rocket and F4 Raider components
1-888-F1AIRCRAFT (1-888-312-4727)
www.flyboyaccessories.com
RV and Rocket Accessories, Tailwheels, Tools, & More
1-888-8FLYBOY (1-888-835-9269)
F4 Raider - under construction
F1-H Rocket "Crazy Horse" - sold
RV-4 "Chief Pontiac" - sold in 1994, purchased in 2018
Last edited by vfrazier : 06-18-2015 at 10:25 AM.
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06-18-2015, 10:43 AM
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Join Date: Jun 2010
Location: Stilwell, KS
Posts: 1,096
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Just a theory...
Not saying you have a Cummins spinner there, but here's my experience with aluminum spinners...
We use Cummins aluminum spinners on our Jabiru LSAs. Been using them since 2008 or so... probably close to 80 airplanes, plus Arion Lightnings. I've seen very few cracks, and the ones I have seen were small and attributed to over-tightening of the screws. I haven't seen anything catastrophic like the OP's picture. Of course, we fly with less horsepower and fewer Gs as well.
The reflection on the spinner in the OP's photo indicates a depression around the screws, which makes it appear that the screws are too tight. We recommend our customers to tighten them down just until snug with a hand screwdriver-- just until the plastic washers begin to compress, and almost zero distortion in the reflection around the screw.
Also, our cones and backplates are match drilled as a finished set at Cummins. If the Van's backplate has a slightly different angle to the flange than the spinner cone and you tighten it down that much, I could see it forming a stress riser and cracking over time--especially with the large distance between the prop cutout and the torn hole, which probably allowed the edge portion to vibrate excessively. But the spinner manufacturer would have more data about that.
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Katie Bosman
RV-3B sold, but flying!
Next project: ???
Builders gonna build...
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06-18-2015, 12:15 PM
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Join Date: Jun 2005
Location: SoCal
Posts: 2,452
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Quote:
Originally Posted by vfrazier
Use tape, if needed, to shim up any gaps in the fitment between the spinner and the spinner backplate.
YMMV!!!!
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That's how we fixed them. We used plastic/vinyl tape.
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Axel
RV-4 fastback thread and Pics
VAF 2020 paid VAF 704
The information that I post is just that; information and my own personal experiences. You need to weight out the pros and cons and make up your own mind/decisions. The pictures posted may not show the final stage or configuration. Build at your own risk.
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