RV-10 Nose Gear problem

[douglassmt]

Originally Posted by vic syracuse

I will be talking with Van's this AM as soon as they open. If you look at WD-416 it has nice braces welded to it. The top should have the same kind of supporting braces, and this failure would not occur. The top looks like a Dynafocal mount ring that has had a pice of 1/8" 4130 welded to it. It is under constant flexing and it is not surprising that it has failed in this manner.

Vic

I'll be inspecting mine this weekend. Good catch Vic and please keep us posted on what you hear from the factory and what you figure out for a fix. Other -10 owners should report in on the condition of their mounts. For whatever it's worth, I'm at 2.5 years, 580 hours, 99.9% on paved strips, never added any washers to the top.

[vic syracuse]

It definitely needs welded bracing INSIDE the dynafocal cup. As a preventative measure, I think putting a thicker steel plate on the bottom BEFORE any cracking occurs should help alleviate the flexing and will delay the cracking. It may prevent it altogether if done proactively.

Mine will require removal of the engine and mount to repair.

I forget who asked earlier, but the top Lord mount is cracked as it was pushed up into the cracked mount. That's why they both look cracked.

Vic

[Bill.Peyton]

I will be checking mine in the morning. Vic, have you spoken with Vans yet and what was their position. I suspect that we will all be removing our engine mounts to address this issue.

[douglassmt]

FYI, Aircraft Spruce has the Lord disks in stock.

http://www.skygeek.com/j11968-14.html

[vic syracuse]

Yes, spruce has The Lord mounts, and so does Van's. They are aware of the he problem and working to address it, so let's give them some time.

Vic

[BobTurner]

Originally Posted by vic syracuse

. As a preventative measure, I think putting a thicker steel plate on the bottom BEFORE any cracking occurs should help alleviate the flexing and will delay the cracking.

Vic

I agree, especially if that plate or washer is at least as large in OD as the cup. Maybe even a Bellville washer, concave side up. It looks to me like the root cause is that the donuts should have been larger diameter. You want the load applied to the cup, not the plate.

Hope Carol is doing okay.

[Gary 40274]

Originally Posted by vic syracuse

Well, my earlier post today requesting help for parts turned out to be a very serious problem. Carol is working on adding the pictures when she gets to her hotel room, but here is the synopsis.

First, thanks for all who replied or called. I ended up flying over to FFC and borrowing Scott Flandermeyer's weldment, as he had not yet installed his nose gear. So I was very excited to have what I thought was the part I needed.

Upon disassembly it turns out that there was severe cracking where the rubber mooney-style lord mounts push up against the engine mount socket. When I say severe, this was to the point of imminent failure. I am not an engineer, but it certainly appears that the surface area that these shock absorbers press against is 1) not large enough, and 2) not thick enough. This should not be cracking in this manner. The piece that is cracking is 1/8" thick. I think it should be at least 1/4".
I have kept these mounts tight by adding washers whenever I thought there was room to add some. I measured the thickness of the new Lord mounts, and they are 1.12" thick. My mounts were 1.01-1.03 thick from the compression set over 5 years and 900 hours. The pictures will show the engine mount socket looking up from the bottom. It is cracked like a pizza, and the pieces are loose. The other picures will show the top of the top-most rubber isolator, and the two stacks of isolaters next to each other for comparison.

As I mentioned earlier, I discovered this quite by accident by noticing a hairline crack on top of the engine mount socket. It looked minor until I disassembled it.

I would recommend that this particular area should probably be looked at very closely every 500 hours, especially if operating off of grass.

BTW, every takeoff at home is begun with full aft stick such that I unstick the nosewheel very early in the run (like we all learned when doing softfield takeoffs). Even on pavement I get the nose off very early.

Clearly I won't be flying the 10 to Ohio tomorrow.









Vic
__________________

What is your suggestion as to inspection procedure? Do you think a visual inspection of the upper donut mount while assembled is sufficient or is disassembly needed?

Gary

[vic syracuse]

I first noticed that something was not right when I saw a hairline crack when looking at the mount area from the TOP of the airplane with the top cowling removed. There was a faint sign of rust along the weld seam of the bottom plate. You can see it pretty clearly in the pictures.
If you wait until the cracks show up in this manner it will be too late as the damage will have occurred. I think a proactive inspection at the next annual, or sooner if high time, is probably warranted.









Vic

[Gary 40274]

I inspected mine this morning. I completely disassembled the donut assembly and found nothing amiss.

I fly off of Grass, have 400 hours on the plane. My stacked height of the donuts was 4 3/16.

Hope this data point helps.

Gary

[ajay]

I don't know if it at all related, but I was looking at the antisplataero.com "nose job" reinforcement. Probably more of a problem for the 2 seater A models, but I think the 10 could use some extra reinforcement if you fly a lot of unimproved airstrips.

ajay