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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: 2,371
Default Engine Mount Cracked Tube at Lower Left Engine Bolt

Im 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 lower tube looks fine. I suspect the failure is induced stress from welding. Perhaps the normalizing process wasnt 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. Im 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 Vans
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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 650

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 02:04 AM.
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  #2  
Old 03-09-2021, 08:05 AM
NinerBikes NinerBikes is offline
 
Join Date: Dec 2018
Location: Granada Hills
Posts: 1,122
Default

How many hours, now, on the Hobbs meter?

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?

Mostly grass field landings?

Did you also show cracks on the outboard main gear landing attachment points, and what was Van's solution to that ?
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2012 RV-12, #212 N72DJ KWHP based.

Last edited by NinerBikes : 03-09-2021 at 08:07 AM.
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  #3  
Old 03-09-2021, 09:34 AM
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Piper J3 Piper J3 is offline
 
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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 650

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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  #4  
Old 03-09-2021, 03:23 PM
NinerBikes NinerBikes is offline
 
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Location: Granada Hills
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Thanks for response... Buddy with N120RV next row of hangars over had to replace his lower engine mount a couple of years back on conditional inspection while doing his 5 year hoses.

He just completed another conditional earlier last week, no new cracks. About 650 hours now, for him.

Buddy with N836BL next door is at 300 hrs Hobbs, with inspection due in April, I think. Will post up what he finds.
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2012 RV-12, #212 N72DJ KWHP based.

Last edited by NinerBikes : 03-09-2021 at 03:27 PM.
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  #5  
Old 03-09-2021, 03:54 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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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 650

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, 05:24 PM
NinerBikes NinerBikes is offline
 
Join Date: Dec 2018
Location: Granada Hills
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Direct quote from text message.

"Everything was Ok this inspection, I had one replaced in 2019 during the 5 year rubber maintenance. I believe it was the lower one, the other two were OK"


Make of it what you will... don't shoot the messenger pigeon.
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2012 RV-12, #212 N72DJ KWHP based.
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  #7  
Old 03-09-2021, 05:53 PM
Harvey rv12 Harvey rv12 is offline
 
Join Date: Apr 2015
Location: Olympia WA
Posts: 188
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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 Vans mention an upcoming SB to deal with this?.
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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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  #8  
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 Vans mention an upcoming SB to deal with this?.
No, only what I reported above.
__________________
-
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 650

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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  #9  
Old 03-09-2021, 07:50 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 3,020
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Bummer, Jim. Are you going for a weld repair or complete replacement?
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  #10  
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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