What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Help: Cracks in Landing Gear

mbauer

Well Known Member
Help: Cracks in Landing Gear Mounts

Today started my annual condition inspection for the RV. Found some cracks in the landing gear mounts. My mechanic is learning about RV's.

Not sure if these are something that can cause issues down the road.

Here is the only photo that is in focus, other side is almost identical to this photo:
Dscn2292.jpg


Remember reading about cracked landing gear mounts on the big tire thread.

Wondering if these need fixed or ok to continue flying....

Looked on the top side welds, and as far underneath as we could, these cracks are both located in the same spot, on both mounts. No other cracking visible.

Best regards,
Mike Bauer
 
Last edited:
Needs to be fixed. On the older mounts there is an inner sleeve that is only welded around the bottom circumference and yours is coming out judging by the oily residue on the bottom of the socket.

I welded my cracks together, added a reinforcing sleeve over the bottom, and added more filler to the existing welds to repair the bottom.

https://goo.gl/photos/J2LYRKMfiTbY7iAe6
 
Today started my annual condition inspection for the RV. Found some cracks in the landing gear mounts. My mechanic is learning about RV's.

Not sure if these are something that can cause issues down the road.

Wondering if these need fixed or ok to continue flying....

Looked on the top side welds, and as far underneath as we could, these cracks are both located in the same spot, on both mounts. No other cracking visible.

Best regards,
Mike Bauer

Cracks such as you are seeing are quite common on RV-6 mounts. I first noticed these cracks a few years after flying my RV-6 and watched them for the next ten years. They never got larger and there was no other cracking. These seem to be compression failures instead of failures in tension.

I finally decided to pull the mount away from the firewall enough to run a weld bead over the cracks. In a couple more years the new weld on the left side had cracked in the same place. I'm back to checking the crack at each condition inspection and don't intend to address it again as long as it doesn't get any worse. I don't have any concern about the mount failing. RV-7 mounts have a gusset in the area and the gussets are available from Vans if someone wants to add them to the RV-6 mounts.

That is my way of dealing with this, others may want to deal with it differently.
 
As Sam learned, welding over the top, even grinding the weld down and welding new won’t work. It doesn’t fix the design flaw.
The only fix is to add the gussets and supports, or roll your own as Bob did. The problem was well known when I was building and most newer build 6’s, early 2000 and up, used the newer 7 mount. I believe Vans consolidated when the 7 came out and switched to the 7 in the finishing kits for the 6.
There is a significant difference, probably even overkill, in the mount. Not just plate gussets, but added tubing as well.

You could always follow Sams inspection approach. Thus far, no mounts have left an airplane that I have heard of and I would bet there are hundreds of 6’s flying out there with cracks at that same spot.
 
It?s a little hard to tell just how far along this is from your photo, you and your A/P will have to decide when and if you need to stop watching and take action, When that time comes I have repaired several of these and installed the gussets from Van?s.

About the grease, Bob could be right but also the legs are usually greased when they are installed so it?s pretty common to see some working out from around the leg.
 
The engine mount is primary structure. You have experienced a partial structural failure. IMHO, The question is not "IF" you should fix it, its HOW should you fix it. Obviously, rewelding is going to simply kick the can down the road until it cracks again. The joint needs additional support, which Vans has very conveniently engineed for the product line. If I know Van's, the gusset plates can be had for a paltry sum, and installation will not require any unusual skills. Blast and powdercoat should be inexpensive (my Rocket mount was done for $60).

This is not a military jet or airliner that needs to support a particular ops tempo - its a sport airplane that can sit for a few weekends. Very simple choice, really.
 
The engine mount is primary structure. You have experienced a partial structural failure. IMHO, The question is not "IF" you should fix it, its HOW should you fix it. Obviously, rewelding is going to simply kick the can down the road until it cracks again. The joint needs additional support, which Vans has very conveniently engineed for the product line. If I know Van's, the gusset plates can be had for a paltry sum, and installation will not require any unusual skills. Blast and powdercoat should be inexpensive (my Rocket mount was done for $60).

This is not a military jet or airliner that needs to support a particular ops tempo - its a sport airplane that can sit for a few weekends. Very simple choice, really.

Oh good grief....this situation doesn't call for a bunch of hand wringin'.......

My RV-6 (and who knows how many others) has "experienced a partial structural failure" for nearly twenty years with no consequences. If the OP decides to pull his firewall-forward apart and weld in some gussets that is just fine. But to place this particular matter in the category of "structural failure" is uncalled for. In the two decades I've been in the RV community I don't recall any gear failures attributed to these small stress cracks.
 
Oh good grief....this situation doesn't call for a bunch of hand wringin'.....

Hand wringing? Please spare us the hyperbole. As much time as people spend on theoretical failures, I can't believe there is even a debate on this actual one.

The part is not up to the task and has cracked. Would anyone submit this airplane to a DAR or the Feds for initial certification with a known crack? Does anyone think a DAR or Fed would let it slide? Why is there even a discussion here?
 
I also had a "partial structural failure" and let it go for a couple of years but kept an eye on it. On one flight I noticed a change in how the airplane tracked down the runway so I pulled the cowl to have a look. Look at the pictures I posted and you'll see the size of the crack it turned into. Its better to fix it now than have a sudden failure away from home. In hindsight I shouldn't have let it go.
 
Wondering if these need fixed or ok to continue flying

Best regards,
Mike Bauer

There?s a lot of people in the Experimental category with bad attitudes. Many give advice on VansAirforce with the intent of justifying their own slack behaviour. In this case you would be wise to ask Vans. I think I have a pretty good idea what they?ll tell you to do. ;)
 
Thank You All!

Looks like I will be getting the gussets and TIG welding them into place.

I like doing T &G's, probably what caused this to happen with 851.2 hours on the airframe.

Zinc chromate primer needs repainted due to lots of zip ties in use instead of Adel clamps.

Work at a welding supply store, have a huge table in the back that is 1" thick steel plate. Thinking to drill holes with a mag drill in it to bolt the mount down and hold in place while TIG welding the fix.

TIG welding doesn't have such a large heat affected zone like acetylene torch or MIG welding creates. Great time to re-primer and then paint engine mount....Assuming since this is a cluster weld that normalizing will be needed once fixed.

Sam did you normalize after you welded yours?

Captain Avgas: Yes, contacted them by email before posting here-since late on Friday, knew they would not reply right away, so thought to ask here.


Remembered reading a thread on this a few months ago, Pittsartist supplied the link I couldn't find.

Best regards,
Mike Bauer
 
Needs to be fixed. On the older mounts there is an inner sleeve that is only welded around the bottom circumference and yours is coming out judging by the oily residue on the bottom of the socket.

I welded my cracks together, added a reinforcing sleeve over the bottom, and added more filler to the existing welds to repair the bottom.

https://goo.gl/photos/J2LYRKMfiTbY7iAe6

When I found my crack in late 2017, I was told that they now machine the main gear leg socket rather than weld them up. So, when I sent my mount to www.super-12.com, they created a jig from it and welded up a completely new mount for me. When I bolted in my replacement mount, it lined up very well with the cowl.

On a side note, I spoke to an IA the other day who had overhauled an engine on an RV-6. He told me that whenever he overhauls an engine on any airplane, he sends the mount off to get stripped and inspected for cracks. His thinking was that at 2000+ plus hours, the engine mounts should all be looked at very closely. I can't fault his logic.
 
Looks like I will be getting the gussets and TIG welding them into place.

I like doing T &G's, probably what caused this to happen with 851.2 hours on the airframe.

Zinc chromate primer needs repainted due to lots of zip ties in use instead of Adel clamps.

Work at a welding supply store, have a huge table in the back that is 1" thick steel plate. Thinking to drill holes with a mag drill in it to bolt the mount down and hold in place while TIG welding the fix.

TIG welding doesn't have such a large heat affected zone like acetylene torch or MIG welding creates. Great time to re-primer and then paint engine mount....Assuming since this is a cluster weld that normalizing will be needed once fixed.

Sam did you normalize after you welded yours?

Captain Avgas: Yes, contacted them by email before posting here-since late on Friday, knew they would not reply right away, so thought to ask here.


Remembered reading a thread on this a few months ago, Pittsartist supplied the link I couldn't find.

Best regards,
Mike Bauer
You?ll find bolting it down to the table isn?t needed or even desired for this fix, for the most part you?ll find you need the mount upside down on your table or you won?t be able to get to much of the work/repair area. Have fun 👍
 
Just home from weekend out of town. Sorry for the late post.

The RV-6 gear leg engine mount crack is common. Back in 2013 Joe at the Factory reported cracks first occurred on RV-6s operating out of GRASS fields. Recommended fix was to add WD-762A-L and WD-762A-R Gear Socket Gusset.

I found the cracks on my RV-6 somewhere around 2,700 hours. The WD-762A-L & R were installed September 2013 on my aircraft. I used an aerospace welder to do the work. I did NOT remove the engine from the mount but moved the engine and mount forward from the firewall far enough for the welding to take place.

I did not stop flying the aircraft when the crack was discovered. I checked with factory and had the repair done with the correct parts before the next once a year Condition Inspection.
 
Received Gussets From Vans Today

Ordered both gussets from Vans, they arrived today.
P/N WD-762A-L & WD-762A-R for $7.60 each.

Vans was quick to reply to my inquiry about the cracks.

One thing mentioned in an email reply, was when welding do a little at a time. This keeps the heat from damaging the gear legs. Interesting! Sounds like it is ok to weld with the gear legs still in the mount.

Already had a professional welding buddy take a look at the mount. He thinks it can be welded in place using TIG.

Will be finding out real soon.

Best regards,
Mike Bauer
 
Are the gussets just flat steel stock?
I am curious as the 7 mount I used on my 6 has tubing for reinforcements in the area you would weld the gusset.
 
Here is a Photo

Are the gussets just flat steel stock?
I am curious as the 7 mount I used on my 6 has tubing for reinforcements in the area you would weld the gusset.

No, not flat. They are marked Left and Right, here is a photo:
Gussets.jpg


Hope this helps. Cheap at $7.60 each.

Best regards,
Mike Bauer
 
Yup, that’s what I meant. It’s flat stock cut and bent. I would imagine they supply these for ease of welding vs tubing as used in the factory 7 mount. Thanks for taking the pics.
Good luck with your repair and send us pics when ur done.
 
Hello Mike

Can you post a foto of the gussets hold in place at the mount?

I need some for a RV-4 mount ... dont know if Vans also have them, otherwise I will do them myself, if I can get the position how they get placed.

Many thanks!
 
Hello Mike

Can you post a foto of the gussets hold in place at the mount?

I need some for a RV-4 mount ... dont know if Vans also have them, otherwise I will do them myself, if I can get the position how they get placed.

Many thanks!
Will do once my welder shows up to do the job. He is out of town on a project. Remote location will be gone at least two weeks.

Right now plane is getting all taped up for a paint graphic addition.

Best regards,
Mike Bauer
 
Back
Top