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RV-10 Nose Gear problem

vic syracuse

vic syracuse

Well Known Member
Advertiser
Mentor
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
__________________
 
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Hi Vic, glad to hear you headed off a problem before it turned into a bigger problem.

And more importantly, I'm sorry to hear about Carol's mom dying last night. Sincerest sympathies to you and your family.
 
The fleet leader in UK (built by the LAA chairman) had a similar issue a couple of years ago - he also flies a lot off grass. He suffered a partial collapse of the nose leg, fortunately without further damage.

IIRC, his fix was to weld bracing pieces around the offending part.
 
Vic,

Are your flights mostly two up front?

My nose wheel is very light with the family on board and probably makes a big difference. 350 lbs at the nose wheel can be over 1000 lbs at that link. Much more during landings.
 
Nose weight

I mostly fly it by myself. I really don't believe this should fail in this manner.

Vic
 
Not clear

I'm not clear what is cracking. From the first picture it appears it is the part on the plane that the washer/cushion stack press against. From the other pictures it's clearly the washers. Or is it both?

Never mind, I read for comprehension and it certainly seems that both are cracking. I can't recall without looking at mine, but is the part on the engine mount replaceable or are you looking at replacing the entire engine mount?
 
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braces needed

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
 
Thanks Vic!

Hopefully, by the time I'm ready to order my RV-10 mount, there will be a fix at the factory. I can't imagine an SB that would make sense, because it would mean replacing the mount periodically (when cracks are found) and disassembling to inspect on perhaps an annual basis. ugh..
 
Let us know

vic syracuse said:
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
Click to expand...

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.
 
temporary fix

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
 
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.
 
Spruce

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
 
vic syracuse said:
. 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
Click to expand...

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.
 
Inspection suggestion

vic syracuse said:
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
__________________
Click to expand...


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
 
Signs of cracking

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
 
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Nose Gear Insp

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
 
nose gear

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
 
I inspected ours this morning and found no issues. I think I'll wait and see what Vans has to say for a fix. I have 300 hours on the airframe, all on hard surface runways.
 
ajay said:
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
Click to expand...

The AntiSplat devise would do nothing for a -10. I know of 2 cases where the nose gear has folded under and both times it was the strut with the rubbed donuts that tore off the bolt that goes on the hat and folded back. There has been some damage to the gear leg, but nothing substantial. Needless to say, in both of these cases the prop struck and the engine mount and firewall had to be replaced. They were both extreme situations, not on a runway from a hard landing or excessive braking. The -10 uses these rubber donuts for the shock absorption, where the other planes use the flex of the nose leg itself for the shock absorption.
 
Jesse said:
The AntiSplat devise would do nothing for a -10. I know of 2 cases where the nose gear has folded under and both times it was the strut with the rubbed donuts that tore off the bolt that goes on the hat and folded back. There has been some damage to the gear leg, but nothing substantial. Needless to say, in both of these cases the prop struck and the engine mount and firewall had to be replaced. They were both extreme situations, not on a runway from a hard landing or excessive braking. The -10 uses these rubber donuts for the shock absorption, where the other planes use the flex of the nose leg itself for the shock absorption.
Click to expand...

Good data points Jesse, I guess the only thing you can do is ride a wheelie!
 
Vic's problem is disturbing. The truth be told, one of the two accidents I mentioned looked very similar to Vic's pictures, but that was after the plane went into the ditch and the nose gear folded back, so I think the cracking was caused by the accident.
 
Ok here

I disassembled mine today - it was easier than I thought with the help of #2 son - and all looked fine, no evidence at all of failure of The Lord plate or the cup.
Pictures of the top before disassembly:
IMG_3709_zpsdee13238.jpg

IMG_3710_zpsc3a756c2.jpg

(The black spot is a drop of oil)

Picture of top of "cup" after disassembly:
IMG_3718_zps666c4178.jpg


Picture of bottom of "cup" after disassembly:
IMG_3713_zpsec63c630.jpg

The mottling is just wear of the powder coat. I greased this area with Lithium grease but I saw no evidence of cracks or deformation.
Note slight abrasion to two welds at 4:00 and 7:00, which is where the brass disc on the top Lord was conflicting slightly.

The brass disc on the top of the top Lord was slightly deformed in two places at the outer edge where it had been in slight contact with two welds on the "cup."
Pic of affected Lord disc:
IMG_3716_zps4f0dcf8e.jpg


I flipped some of the Lord cushions around and greased everything with some lithium grease then put it back together. I relieved the edge of the new top brass disc to prevent conflicting with the welds. The 4 lord cushions were exactly 4.25" uncompressed.

I was able to easily add the second washer, but there was no play in that area when I lifted the nose off the ground and moved the gear leg up and down prior to disassembly. All the play seemed to be in the bushing, but it wasn't much.

580 hours TT, 99% on good hard surface. I always aim for good Mike Seager nose wheel discipline as Vic described.
 
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I took mine completely apart to inspect it and found no signs of cracks. I decided to replace the 4 rubber bushings with new ones since they were compressed.


I have 998.8 hours on it, most of it off of our grass runway.

Should roll over to 1000 hours this week.

Rob Hickman
N402RH RV-10
 
Age of kit??

Rob, Vic---------what vintage kits do you two have....or serial number would be fine also.

Thanks.
 
mine (well it used to be mine) did the same exact thing recently, identicle to the pics posted here.
mine faier completely and the nose gear would try to fall out of the mount after liftoff. didnt catch it right away, the only thing that saved the aircraft was about 1/8 of bolt thread which was just a little too long to pass through the cup opening on its way down. it was bending and i guess about 5 to 10 more flights we would have lost the airplane on landing.
the tech guy at vans says thats the first hes heard of it.
the plabe does go on grass and rough strips from time to time.
those cracks are classic fatigue symptoms. i had an aerospace welder make a thicker bottom plate and put a reinforcing ring internally. should have the engine back on this week.

Louis Palmenteri
RV-6, 10 building -8
 
if i was building an rv-10 there is no way id put the current mount on my plane without beefing it up. it is so much work to take the engine and mount off 3 or 400 hours down the road.
 
Agree, but....

I agree with needing the stronger plate, but as I mentioned in an earlier thread Van's is aware of the problem and are working on both:
- a new design that will replace the current mount
- a way to modify the existing mounts in the field

My guess is this will be quickly forthcoming, so be be patient. :)

Vic
 
vic syracuse said:
I agree with needing the stronger plate, but as I mentioned in an earlier thread Van's is aware of the problem and are working on both:
- a new design that will replace the current mount
- a way to modify the existing mounts in the field

My guess is this will be quickly forthcoming, so be be patient. :)

Vic
Click to expand...

Glad to hear this, was wondering why there was no input from Scott or one of the other Vans folks in this thread.
 
Caution regarding where grease is used FYI

douglassmt said:
The mottling is just wear of the powder coat. I greased this area with Lithium grease but I saw no evidence of cracks or deformation.
Note slight abrasion to two welds at 4:00 and 7:00, which is where the brass disc on the top Lord was conflicting slightly.

I flipped some of the Lord cushions around and greased everything with some lithium grease then put it back together.
Click to expand...

Since it is not clear from your post what "greased everything" means exactly, I thought I would mention that it is very important to not ever put any kind of lubricant on the shaft WD-1016 nose gear link assy. where it penetrates the Lord Nose Gear Elastomers.
The friction induced on the shaft by the elastomers when they get compressed (which causes them to expand more tightly against the shaft), is a design function of the elastomers to provide damping. Any lube that would allow them to move more easily against the shaft is compromising the nose gear design (not to mention that petrolium products on rubber compounds are usually not good for longevity).
 
Bill.Peyton said:
Scott,
Do you have a status on this "fix"
Thanks
Bill
Click to expand...

It is being actively worked on.
An FEA model was made and analyzed and work is underway to finalize a modification for field retrofit and future production (likely not the same mod. for both, but of equal strength).

General FYI...
The original RV-10 prototype (N410RV) now has just shy of 2000 hrs. There have been no signs of damage in this area (we try and watch our airplanes closely so we see things coming before customers do), but it has only been operated from grass a small percentage of its flight hours.
So, all indications are that unless you operate off of rougher runway surfaces a large percentage of the time, there is no reason for immediate concern. Particularly if your airplane is low in flight hours.

Please don't ask me what the fix will be or when it will be available, because until the mod is released, final decisions wont have been made. I can say that effort is being made to make the mod. as simple and painless to install as possible. Unfortunately, those builders that do find damage will have a bit more of an involved process, but all data at this point indicates that only a very small # of airplanes are likely to be effected in that way.
 
As a very soon to be RV-14 builder I've been following this discussion, and not to hijack the thread, but does anyone know if the RV-14A nose wheel has been designed to better withstand such wear and tear?

Thanks,

Greg
 
Hi Greg.

Sounds like you and I are thinking along the same lines. I started a thread "RV14, RV10 Landing Gear" to try and educate myself a bit. Didn't want to get this very important RV10 thread diverted. I wonder if it would be a good idea to make our questions more RV14 specific for now, ie a different thread?

Absolutely no disrespect intended I'm easily labeled a bull in a china shop.:)

I would really like to hear where you are at with your RV14 thinking.
 
Tilford said:
As a very soon to be RV-14 builder I've been following this discussion, and not to hijack the thread, but does anyone know if the RV-14A nose wheel has been designed to better withstand such wear and tear?

Thanks,

Greg
Click to expand...
Unnecessary thread drift.. mods feel free to move RV-14 posts over to the RV-14 thread already under way....

Difficult to answer since the RV-10 gear wasn't purposely designed to not take the punishment of rougher runways, but time in service has shown it not to be. People that have been involved with aviation for a long time know that this is not all that uncommon... for discoveries to be made and then changes designed to account for them.

As was mentioned in the other thread, the RV-14A has a nose gear design that is similar in concept to the RV-10, but the area in question here is different between the two airplanes so the true test will be time in service.
Having said that, each RV model is designed using the knowledge and experience gained from previous designs, so in all likelihood, this type of problem shouldn't be seen on the RV-14A (until somebody puts an IO-540 on the front :rolleyes:)
 
Training!

rvbuilder2002 said:
It is being actively worked on.
General FYI...
The original RV-10 prototype (N410RV) now has just shy of 2000 hrs. There have been no signs of damage in this area (we try and watch our airplanes closely so we see things coming before customers do), but it has only been operated from grass a small percentage of its flight hours.
So, all indications are that unless you operate off of rougher runway surfaces a large percentage of the time, there is no reason for immediate concern. Particularly if your airplane is low in flight hours.
Click to expand...

I don't know what the exact percentage of grass vs hard surface time the company -10 has, but it has certainly operated off of Mike Seager's grass strip at Vernonia many hours, and with transition STUDENTS! That has got to put some stress on it above normal. I know that JackM really punished it during his training with Mike:D
 
The landing gear on the RV10 seems to be a real problem point. There simply isn't enough meat far enough forward. This is the rv10 nose wheel picture from before. Take note a the angle of the donuts to the direction of force. The donuts need to be at more of a perpendicular angle to the nose wheel leg to better absorb energy.
JvWHzNY.jpg

w6V1dkWl.jpg

This is the nose wheel assembly from the older SR22. Notice how much material is on the is wheel mount. Also take not at how far forward it goes. As you can see the rubber donuts are close to perpendicular to the direction of force. This is easy for cirrus to accomplish because the Continental engines are mounted from the bottom, where the 10s are from the rear.
zbHOi1Bl.jpg

This is the nose wheel assembly from the new SR22. They completely went away from the rubber shock mounts and went to a very small oleo strut. Notice how the oleo is still nearly perpendicular to the nose wheel leg and in better position to absorb shock. Also take not at the fork itself. On the RV10 the for is close to level whereas the SR22 is closer to a 45degree from level. So where a large nose load may cause the fork to grab on a 10, it will not on a Cirrus. This later Cirrus landing gear can be duplicated on the 10 if we can figure out a mounting point for a perpendicular oleo strut or donut.
 
I don't agree

Sorry, but I disagree with most of this post. The landing gear on the -10 isn't a problem point. We have - so far - very few out of over 700 planes that have exhibited failures of a portion of the nose gear load absorbing system. Not all of them are high time birds and some high time -10s have had no failures. The angle of the WD-1016 has nothing to do with how much energy it absorbs because both systems absorb all of it...else it would fail every landing. The failures have been located where the load is absorbed and are not based on how much is absorbed. An oleo strut might be nice, but I suspect it is much more expensive and the Lord elastomers are not the problem here - it seems to be the "cup" where the WD-1016 terminates. Simple is good.

There may be some improvements that can be made to either the design or the manufacture of the "cup" where the WD-1016 terminates but there has not been a problem with most mounts. We haven't even determined whether it is a design or a manufacturing problem. I think it's safe to say (don't know him, just going on reputation and his posts) that Vic is as careful and smart a pilot as we have and for his to fail is a significant data point - it could very well be manufacturing flaws that only affect very few mounts. Note again that other high time -10s that fly off grass are fine.

As for the for the nose fork, the angle of the fork relative to the ground or the nose gear itself is only relevant with regard to the potential to grab the ground and roll under - to my knowledge we have had exactly zero of those occurrences. I can make a pretty good argument that the -10 fork is stronger than the new Cirrus but it would depend on the materials used and the design of the bearing on the Cirrus, which I can't really see. If you look at the -10 nose fork and bearing, it's pretty stout and spreads the load over a large area.

My biggest point is that we don't know enough to make these conclusions and the information we do have indicates that the -10 nose gear is really an effective, simple design. The design or reinforcement of the cup may need some watching in case of manufacturing flaws or fatigue over time and good nose-wheel discipline is always smart. But other than that, I think it's a fine design and plan to keep mine :)
 
I don't believe this particular problem has to do with the angle of attachment. The consequence of the position of attachment to the lever arm is a significant force being applied to the cup area, which seems to exhibit some fragility. The jury is out as to whether this a design defect or manufacturing defect. As Bryan stated, there are a lot of -10s that don't exhibit this problem, at least not yet.
I'm confident that Vans engineering team will develop a solution without a total redesign of the nose gear. Although it would be nice to eliminate the resonant hobby horse shake at 14kts that many seem to exhibit.
 
aviator9587 said:
The landing gear on the RV10 seems to be a real problem point. There simply isn't enough meat far enough forward. This is the rv10 nose wheel picture from before. Take note a the angle of the donuts to the direction of force. The donuts need to be at more of a perpendicular angle to the nose wheel leg to better absorb energy.
This is the nose wheel assembly from the older SR22. Notice how much material is on the is wheel mount. Also take not at how far forward it goes. As you can see the rubber donuts are close to perpendicular to the direction of force. This is easy for cirrus to accomplish because the Continental engines are mounted from the bottom, where the 10s are from the rear.
This is the nose wheel assembly from the new SR22. They completely went away from the rubber shock mounts and went to a very small oleo strut. Notice how the oleo is still nearly perpendicular to the nose wheel leg and in better position to absorb shock. Also take not at the fork itself. On the RV10 the for is close to level whereas the SR22 is closer to a 45degree from level. So where a large nose load may cause the fork to grab on a 10, it will not on a Cirrus. This later Cirrus landing gear can be duplicated on the 10 if we can figure out a mounting point for a perpendicular oleo strut or donut.
Click to expand...

Shawn,
I know this might sound strange coming form someone at Van's (because all of us are hard core aviation people that enjoy helping others have fun in this hobby just like we do.... that is why most of us work here), but I am starting to think that an RV-10 is not a good choice for you.
I spent a lot of time talking with you (and your fiance?) at Osh. You asked lots of good questions... a very good thing (it is important to get educated before diving into a project like this), but then and now, your questions have mostly been focused on safety of design aspects, in comparison to certificated aircraft.
There is nothing wrong with looking at that, and because of your dads accident in an RV-4 that you mentioned, it is understandable. Because of that though, maybe you would ultimately be more happy (and at ease) with another aircraft from the certificated side (like a Cirrus maybe).
Please think that over.... for two reasons....

If you feel inclined to have to redesign everything you think is not optimal, you will never finish. Period.

And, if you don't redesign everything, you will always have things nagging in the back of your mind where you will never feel fully comfortable with the airplane. That inevitably becomes an airplane that rarely gets flown.
 
Be patient

I don't think this is a problem that needs a massive redesign. Clearly, it just needs some beefing up in the particular area where the donuts are applying force. The 4130 plate there is flexing. Whether it is from grass landings, inadequate bracing, or improperly annealed plate after welding, we won't know. So far, it has only affected a few. Will it affect more? Time will tell. My opinion is that there will be others.
It is typical like this to see wear items as the fleet ages and subsequent fixes.

Vic
 
I now have over 1000 hours on my RV-10, most of it flying off of a grass runway. It is a remarkable airplane and has proven to be EXTREMELY reliable, safe and trouble free. We routinely fly it between Portland and Sunriver Oregon across the Cascades with 4 people and two dogs. We will leave Sunriver (4163' Elev) in the afternoon at 90F at gross weight and it will still climb at over 800 Ft/min. About a month ago we landed following a Citation X at Sunriver and I swear we had more baggage + dogs in the plane.

I have a friend that owns a Cirrus G3 Turbo that I frequently pick up when he drops it off for service. He routinely spends more money on a single service visit than I have spent on total maintenance in the 1000 hours.



Rob Hickman
N402RH RV-10
 
Rob, I agree :D

Sorry I missed you at OSH, I even spent a half day or two on the Dynon Stand but never had a chance to compare notes.

They are awesome machines and I echo Scotts comments, some folk SHOULD not buy them.
 
After having a nose-gear incident in the RV-6A and rebuilding to fly again, I am of the opinion that the engineering of these kits is not the primary safety issue. I'd say that builder error is more likely to be a problem and, in light of my own accident, bad piloting can break an otherwise good design. I'm not pointing fingers at anyone else's incident, so no need to go defensive. But I think the track record shows that a properly built and flown RV is a very safe aircraft. On the other hand, aircraft are very unforgiving of even small lapses. I agree with the idea that if you are not completely comfortable with the design then you should probably pick something else to, if nothing else, reduce your stress factor.
 
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