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  #1  
Old 03-09-2021, 02:00 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 2,432
Default Engine Mount Ė Cracked Tube at Lower Left Engine Bolt

Iím just starting Annual Condition Inspection at 633TT and began by looking at engine mount standoff for cracks per SB-00023. Standoff looks good; however, further inspection of the main engine mount found a cracked tube at the lower left engine bolt. Two tubes are welded in a cluster at this location and upper tube is severed in half Ė lower tube looks fine. I suspect the failure is induced stress from welding. Perhaps the normalizing process wasnít sufficient to equalize strain in the two tubes that form this joint.

So, even though the standoff passes inspection I will replace it as long as I have everything apart. Iím also going to do 5-year rubber hoses with High Performance Silicone Heater Hose, install new rubber engine mount isolators, and remove the fiberglass cooling shroud.

Good thing the US Congress is passing the COVID relief bill, it looks like my stimulus check should just about cover the cost of parts.

The photos below are my airplane and one in Australia with a crack recently discovered. The Australian RV-12 has crack in lower right main tube near the oil tank. Both failures have been reported to VanísÖ
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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 : 06-02-2021 at 01:34 AM. Reason: Added Third Photo
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  #2  
Old 03-09-2021, 09:34 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
Posts: 2,432
Default

How many hours, now, on the Hobbs meter? 633TT

Are those cracks showing on the extension side or compression side of the weld joint from the the load of the engine's inertia from gravity when landing? I'm guessing extension

Mostly grass field landings? Yes, grass

Did you also show cracks on the outboard main gear landing attachment points, and what was Van's solution to that? I incorporated a fix that was designed locally. I believe Van's is working on problem. In my opinion, the SB for aluminum channel gear carry-thru is insufficient.
__________________
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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 : 03-09-2021 at 09:37 AM.
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  #3  
Old 03-09-2021, 03:54 PM
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Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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Quote:
Originally Posted by NinerBikes View Post
Buddy with N120RV next row of hangars over had to replace his lower engine mount
I don't follow... Engine mount PN WD-1220 with large ring tube on back is a single weldment. Can't replace "lower engine mount" unless someone is cutting/splicing.

Van's responded today to my email request for information. Engine mount has been redesigned for added strength. New PN is WD-1220-1.
__________________
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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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  #4  
Old 03-09-2021, 05:53 PM
Harvey rv12 Harvey rv12 is offline
 
Join Date: Apr 2015
Location: Olympia WA
Posts: 195
Default

Quote:
Originally Posted by Piper J3 View Post
I don't follow... Engine mount PN WD-1220 with large ring tube on back is a single weldment. Can't replace "lower engine mount" unless someone is cutting/splicing.

Van's responded today to my email request for information. Engine mount has been redesigned for added strength. New PN is WD-1220-1.
Did Vanís mention an upcoming SB to deal with this?.
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Tom O.
RV-12, bought flying
Hoskins Field, 44T
Olympia WA

the bitterness of poor quality
lingers long after the cheap
price is forgotten.
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  #5  
Old 03-09-2021, 07:01 PM
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Piper J3 Piper J3 is offline
 
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Quote:
Originally Posted by Harvey rv12 View Post
Did Vanís mention an upcoming SB to deal with this?.
No, only what I reported above.
__________________
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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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  #6  
Old 03-09-2021, 07:50 PM
RFSchaller RFSchaller is offline
 
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Bummer, Jim. Are you going for a weld repair or complete replacement?
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  #7  
Old 03-10-2021, 03:38 PM
mcems mcems is offline
 
Join Date: Apr 2008
Location: Salem SD
Posts: 171
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why is this not getting more press , this is a pretty big deal.

Brad Stiefvater
124BJ
Salem SD
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  #8  
Old 03-10-2021, 04:18 PM
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Steve Melton Steve Melton is offline
 
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Location: Cincinnati, OH
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typically a commercial airliner landing over 4G should have the engine mounts inspected. I don't know the typical limits for small piston aircraft.
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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com
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  #9  
Old 03-10-2021, 07:44 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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Quote:
Originally Posted by RFSchaller View Post
Bummer, Jim. Are you going for a weld repair or complete replacement?
I ordered new engine mount. Part is in stock but won't ship for a week. Van's is behind because of ice storm, power outage, and COVID.
__________________
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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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  #10  
Old 03-12-2021, 10:41 AM
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Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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I have a new twist on my problemÖ Vanís tells me today that engine mounts are not in stock and expected delivery is May 3.

So, a couple of possibilities:

Does anyone either have a spare engine mount, or perhaps building now and donít need engine mount for a month or two and be willing to send to me for brand new engine mount I have on order?

Second choice would be to repair existing engine mount. See photo below. I can send mount to be welded and would like to use a reputable service. Any suggestions appreciated.
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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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