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  #21  
Old 03-16-2021, 09:49 AM
JFCRV12 JFCRV12 is offline
 
Join Date: May 2015
Location: Liberty Township OH
Posts: 208
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Quote:
Originally Posted by RFSchaller View Post
Bite your tongue, David!��
Agreed! I didn't build my plane, but feel like I'm slowly rebuilding it one SB at a time

Actually, it hasn't been that bad. But I do have to do the gear leg and engine mount standoff in next couple weeks (I have the parts). Time and a helper are all I need.

Still an excellent aircraft. And experience tells me ALL aircrafts break and have/should have a litany of SBs on them.
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  #22  
Old 03-18-2021, 01:26 PM
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Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 2,426
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Weld repair is complete. Chromoly 4130 split over-sleave is TIG welded into tubing cluster.

Third photo shows weld fixture to hold 189mm vertical centerline distance for engine mounting pads.

On closer inspection… on the left side of the mount (broken side) I see heavy internal thread markings in both the top and bottom engine mounting pads. See photos below. I think this engine mount was made incorrectly from the get-go. My guess is the 189mm vertical centerline distance was compromised during initial fabrication, and when assembled to the engine, it caused tension and stress in the lower tube.

Engine mounting pads on the right side of mount look pristine. Now that mounting pad centerline dimension is corrected with this repair, everything should be hunky-dory.
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 670

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H
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  #23  
Old 03-20-2021, 10:25 PM
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cactusman cactusman is offline
 
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It's too bad Van's didn't have one they could exchange and bring yours in for extensive testing and analysis.

Just curious with that time - had you had the carbs rebuilt and do you balance them often or at least annually?

Also - prop balance? Recent or at the initial stages like most of the rest of us did?

Really think the key to long life on this plane is getting those vibrations out and keeping them out.
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  #24  
Old 03-21-2021, 06:09 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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I rebuilt carbs last year and synch checked annually.

This year I will balance prop for first time. I will be interested to see balance improvement. Engine runs extremely smooth at cruise and off-idle.

Reinstalling repaired engine mount - where do all these hoses go???
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__________________
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 670

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H

Last edited by Piper J3 : 03-21-2021 at 06:13 AM.
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  #25  
Old 06-02-2021, 01:34 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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I have added a third photo to my post #1 above. I am in contact a RV-12 builder/owner in Australia. He has now discovered a second crack in the main circular back mounting ring after disassembling cabin heater control cable. He is in process of installing new engine mount after discovering crack on lower right side near oil tank. I would think main circular back mounting ring is very robust and that cracks would appear in thin tubing where engine attaches, like in my instance.

Just a heads-up when doing next condition inspection…
__________________
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Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 670

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H
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  #26  
Old 06-02-2021, 07:04 AM
JBPILOT JBPILOT is offline
 
Join Date: Nov 2007
Location: Jesup, Iowa
Posts: 1,675
Default Another victim - -

I found my standoff mount was cracked more than half the way around on the cross tube. I have no idea what the fix is from Van's, but I ordered it. 1,450 hours. I have balanced prop I think 3 times, and sync carbs every year. I decided not to weld it, but did consider it. Not sure it won't break beyond the weld fix area. Engine torque I assume causes this problem. Hopefully the factory fix will last a long time.
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