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  #11  
Old 10-23-2022, 11:18 AM
bobnoffs bobnoffs is offline
 
Join Date: Jul 2012
Location: n. wi
Posts: 962
Default

didn't everybody put a hands on that weight and wiggle/shake it when you were back there with those ''clips''? i hope the sb just says wiggle/shake.
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Bob Noffs
n. wi.
dakota hawk/jab 3300 built and flying. sold 6/18.getting serious about the 12. in the hangar now as of 10/15/19
RV-12 kit as of 9/13
RV-12 airworthiness cert. 11/30/2021
first flight 7/25/2022
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  #12  
Old 10-23-2022, 11:28 AM
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Snowflake Snowflake is offline
 
Join Date: Oct 2009
Location: Sidney, BC, Canada
Posts: 4,377
Default

Quote:
Originally Posted by scsmith View Post
BTW, is that blood I see next to that nylon zip-tie holding an antenna cable to a longeron/stiffener?
It looks like there are pieces of tubing or something RTV'd to the edge of the stringer, probably to protect the cable where it's cable tied in place. Dried blood would be darker. :P
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Rob Prior
1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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  #13  
Old 10-23-2022, 01:11 PM
Bob Y Bob Y is offline
 
Join Date: Jul 2017
Location: Piedmont, SC
Posts: 427
Default

Quote:
Originally Posted by PilotBrent View Post
God help me if I have to crawl into the back of that tailcone again....
Id rather crawl back there than have to remove the stabilator 😢
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Bob Y - builder 12iS E-LSA
N569TT first flight 2/9/2020
#121047
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  #14  
Old 10-23-2022, 02:23 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 8,552
Default

Quote:
Originally Posted by scsmith View Post

BTW, is that blood I see next to that nylon zip-tie holding an antenna cable to a longeron/stiffener?
I think its red RTV, used to hold the abrasion protection in place. Or a lot of blood!
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  #15  
Old 10-23-2022, 09:10 PM
docjjrmd docjjrmd is offline
 
Join Date: Sep 2022
Location: Cape Girardeau
Posts: 9
Default

Quote:
Originally Posted by Bob Y View Post
Id rather crawl back there than have to remove the stabilator 😢
That depends on how flexible you are. Chase washers and bolts or have trouble walking for 3 days....
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  #16  
Old 10-23-2022, 10:12 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 3,333
Default

One of the mods I did was to install a 4 diameter handhole on the right side of the fuselage near the counter weight. Thats looking more and more like a great decision. I always thought Vans should have added more inspection holes to facilitate stabilator removal and elevator cable wear block replacement. I also replaced those blind rivets on the wear block with machine screws to facilitate replacement.
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  #17  
Old 10-26-2022, 11:38 AM
Skip12 Skip12 is offline
 
Join Date: Dec 2020
Location: Austin/Pflugerville
Posts: 6
Default

There is also some red stuff on the bulkhead.
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  #18  
Old 11-02-2022, 07:22 AM
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joedallas joedallas is offline
 
Join Date: May 2010
Location: Spring Hill Fl
Posts: 766
Default Engine Prop balance and or Blade pitch not the same

The break appears to be broke in the horizonal direction. (small neutral access)
Engine vibration and the length of the tube transmit it to an inertia stable counterweight.

A rubber isolator may solve this problem. (Harmonic balancer)


My view
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Joe Dallas
Kit-#12400
www.joesrv12.com
www.EAA1298.com

Last edited by joedallas : 11-03-2022 at 05:47 PM. Reason: Blade pitch added note
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  #19  
Old 11-02-2022, 07:39 AM
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PaulvS PaulvS is offline
 
Join Date: Aug 2019
Location: Western Australia
Posts: 1,293
Default

My guess is that the plane was parked outside without a control lock on the stabilator and it banged up and down in the wind until the weight attach bracket fractured.
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Paul vS (yes I'm also a Van)
Building RV-6A #22320 O-320 FP. Wings and tail complete, fuselage almost done, working on canopy.
Flying my Aeroprakt A-22 STOL and the aero club's RV-9A while I build
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  #20  
Old 11-06-2022, 08:29 AM
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joedallas joedallas is offline
 
Join Date: May 2010
Location: Spring Hill Fl
Posts: 766
Default The Perfect Storm

This problem has been on my mind since my pervious my post.

I believe this failure is caused from a frequency-based metal fatigue from harmonic vibration. (Over the maximum number of cycles allowed)

Also, the kip frequency caused by the engine balance and the prop balance when in alinement? (caused by the gear box ratio)

The engine Ballance and the prop balance and the gear box move the force in changing degrees from a horizonal plane.

The engine is the on the front end of a teeter totter (so to speak) inertia stable.

The center mass is at the spar, balance point (so to speak), The spar the fuel tank and the occupants. Note full fuel tanks in the wings would help dampen the vibration.

The counterbalance is on the longer arm of the teeter totter (so to speak)

Note my background is in engineering (I am not a wordsmith)


A good prop balance and pitch match would mitigate this problem.

My view



From my pervious post

Quote:
Originally Posted by joedallas View Post
The break appears to be broke in the horizonal direction. (small neutral access)
Engine vibration and the length of the tube transmit it to an inertia stable counterweight.

A rubber isolator may solve this problem. (Harmonic balancer)


My view
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Joe Dallas
Kit-#12400
www.joesrv12.com
www.EAA1298.com

Last edited by joedallas : 11-06-2022 at 10:14 AM. Reason: Typing
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