What's new
Van's Air Force

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

RV-12 accident - August 2017

Damage to one here in Louisville.

There was a failure on a 12 based out Bowman Field here in Louisville recently. His failed making a turn off the runway at a different airport. Fortunately the wings come off to make transporting the plane back less painful. He suffered damage to more then just the nose wheel. I don't think he follows this forum.
 
I'm just a nobody, but to me, the nose wheel assembly shown in that first photo appears really under-designed. I realize the the RV-12s only weigh...what?... 750 lbs. but even so.

What I see in that first photo is a nose gear that has had the living **** beat out of it. Lots of paint missing and what appears to be grass stains on the front.

Jim
 
The stronger nose fork is $240. I'd estimate that this accident is going to come in at a minimum of $4000 providing the engine is OK (it should be). That's cheap insurance if you're using craggy airports like Rensselaer.
 
Trying to get this thread back on track.....

The stronger nose fork is $240. I'd estimate that this accident is going to come in at a minimum of $4000 providing the engine is OK (it should be). That's cheap insurance if you're using craggy airports like Rensselaer.

I agree with above. Jim is a good and smooth pilot, but Rensselaer's runway has been in terrible shape for years. I speculate (there, I said it!) that this failure was the result of metal fatique induced by many many stress cycles. I agree that anyone who operates routinely from rough fields ought to consider the "cheap insurance". Even though I only visit grass or rough fields occasionally, I think I will replace the fork at the next CI. JMHO.
 
530 hours on the aircraft. I'm the only one who's ever flown it, and it's never had a hard landing or nose wheel landing. Seems to me like the fork is a really weak point & poor design. Damage resulting from this failure is extensive. Had the aircraft pole-vaulted as the strut dug into the runway, I'd have been trapped upside down and likely unable to evacuate the aircraft as the canopy rested on the surface with the full weight holding it shut.
 
People are funny

The stronger nose fork is $240. I'd estimate that this accident is going to come in at a minimum of $4000...
I'm old, so I've noticed along the way that some people are funny that way with their money. The guy in the hangar behind me owns a Lightning with similar nose gear. On a test flight he muffed a landing badly - ended up in the weeds - and curled back the lower part of the gear. I advised the guy to buy a new fork from the factory but instead he just had a shop beat it back into shape. That kind of thinking (or non-thinking) is foreign to me.
 
fracture mechanics

FATIGUE CRACK GROWTH ANALYSIS
=============================

I am not sure what this means precisely, Steve, but would certainly agree that running some 2-3-4 cycle drop test is not adequate for evaluation of a fatigue failure. Fatigue loading tests, FEA, and Weibull analysis of field failures to indicate percent of population that will fail is the way to properly address this as an issue. Being aluminum they will all fail eventually, but the design life here is not known. Even the design targets are not known, but I doubt the target is ZERO for an infinite life.

It looked like that test began with a crack and ran 180 cycles, did it then fail?
 
My 2 cents . . .

I wasn't debating the goal, just pointing out that there is often times a failure in the system (and that it seems you are implying that any component failure on an aircraft deserves an AD and correction on all aircraft of the same Make/Model...that is simply not true), but this is getting way off track from the original point of the thread.
I have nothing more to add.

As for Scotts comments here, in this forum - - in my view:

Scott posts here as a courtesy to we builders and owners. He is not to represent the official engineering analysis and decision making of Vans as a whole. I take his comments in that context and not as an absolute or complete justification for the Vans official position. Some of his arguments are clearly insufficient to make this engineer happy, but that is beyond expectations for his participation on this forum. We politely take what we get and if we don't like it, pick up the phone and call Vans, or send an email. It just seems rude to attack our only source of any enlightenment here and cause his blood pressure to rise.

Something to think about, put yourself in his position.

I have nothing more to add :D
 
MY view

My View
This forum is a great way for all of us to present our view and concerns.

Scotts participation is impotent to help understand a different view.

His view is of his opinion only and not necessarily those of his employer ( he has made that clear )

This is a great way to communicate with vans and let them know our concerns.

The community on the whole is better than anyone persons view.

I am sure that vans is aware of the problem and only they can decide the extent.


MY view

Joe Dallas




As for Scotts comments here, in this forum - - in my view:

Scott posts here as a courtesy to we builders and owners. He is not to represent the official engineering analysis and decision making of Vans as a whole. I take his comments in that context and not as an absolute or complete justification for the Vans official position. Some of his arguments are clearly insufficient to make this engineer happy, but that is beyond expectations for his participation on this forum. We politely take what we get and if we don't like it, pick up the phone and call Vans, or send an email. It just seems rude to attack our only source of any enlightenment here and cause his blood pressure to rise.

Something to think about, put yourself in his position.

I have nothing more to add :D
 
Last edited:
The stronger nose fork is $240. I'd estimate that this accident is going to come in at a minimum of $4000 providing the engine is OK (it should be). That's cheap insurance if you're using craggy airports like Rensselaer.

I looked up New Version WD-01230 12 NOSE FORK CONVERSION and it appears the going price is $325.00

Oh well...
 
Original to Conversion

Does anyone know if the wheel pants on the original nose wheel design will still work on the new fork?
 
Does anyone know if the wheel pants on the original nose wheel design will still work on the new fork?

There is NOTIFICATION 16-09-21 on Van's website the delineates the upgrade; there is a wheel pant upgrade kit required if you change the fork. I have not done this modification, but the kit is $20 and essentially a couple brackets to account for the new axle location which is slightly different from the original. But the wheel fairing itself will still work.
 
Chuck,
I know a couple of friends, one with a 9 and one with a 7, had done some changes to their nose gear, but they had more of a geometry issue, not cracking. I've seen other aftermarket stiffeners the other A models can consider attaching to their nose gear leg, but again nothing to do with cracking.

This is information within my small circle of RVs at my home base.
 
I am not sure what this means precisely, Steve, but would certainly agree that running some 2-3-4 cycle drop test is not adequate for evaluation of a fatigue failure. Fatigue loading tests, FEA, and Weibull analysis of field failures to indicate percent of population that will fail is the way to properly address this as an issue. Being aluminum they will all fail eventually, but the design life here is not known. Even the design targets are not known, but I doubt the target is ZERO for an infinite life.

It looked like that test began with a crack and ran 180 cycles, did it then fail?

This analysis started with a .5 inch wide crack, .1 inch deep, in the alum weld. The crack growth became unstable at 180 cycles and failed at 3436 cycles. This analysis stress cycles are 0 to 20 ksi. 20 ksi is below the yield strength of the welded material but the crack tip causes a large stress intensity and propagates the crack rapidly.

This is a simple analysis for an alum welded specimen. I don't know the design loads of the fork. The stresses on the fork are different than this case. This analysis simply shows that a crack in an alum weld is something not to ignore because it will only get bigger until failure.
 
Last edited:
. . . "I speculate (there, I said it!) that this failure was the result of metal fatigue induced by many many stress cycles. I agree that anyone who operates routinely from rough fields ought to consider the "cheap insurance". Even though I only visit grass or rough fields occasionally, I think I will replace the fork at the next CI. JMHO."
That's a very measured and level-headed response.
For me, it's a "no brainer," regardless of where you operate out of.
"Cheap insurance?" All should ask themselves, what is one life worth?
 
Last edited:
For locations such as this, where a crack is known to have formed, I recommend a dye penetrant test. This is a very simple to perform test that takes only a few minutes and is essentallly:
1. Clean the affected area with included cleaner
2. Spray die on affected area
3. Wipe off excess dye
4. Spray developer
5. Use a nice, bright light and look for signs of cracks.

This should be added to your annual inspection for the nose fork, and possibly the horizontal stabilizer ribs, and whatever else you think might be susceptible to cracks.

Although there are fancy, schmancy kits, this one from Amazon is more than effective at the job: Dye Penetrant Crack Finder Kit by Silver Seal
http://a.co/9ExqvCx

Ron,
Thanks for the dye penetrant reference, its on order...Doug in IL
 
I as well as other RV-12 owners, I'm sure, would like to know how many fork failures have occurred as well as the number of forks with weld area cracks found including those that had cracks, were repaired, and repaired again (if any). This thread indicates that a "few" failures have occured. Having the data of how many is a "few", would better equip the RV-12 community so that we can individually make a more informed decision as to whether to replace our nose wheel forks with the revised/upgraded design.

Just FYI: I found cracks in my original fork and had Vans repair the cracks. I flew the repaired fork for 4 years, then last year replaced the fork with the original design after discovering during the annual that one hole in the fork was egg shaped on the threaded side of the axle bolt.
 
There is NOTIFICATION 16-09-21 on Van's website the delineates the upgrade; there is a wheel pant upgrade kit required if you change the fork. I have not done this modification, but the kit is $20 and essentially a couple brackets to account for the new axle location which is slightly different from the original. But the wheel fairing itself will still work.

So Van's is telling me... 12 Nose Fork Conversion “subkit” $325.00 “contents” WD-01230-1 “fork” U-01210A-1 “axle” Doc 12 Man Sect 35 Bag 2847.

Is that everything I need to swap out the old fork and still have the front wheel fairing mount up to the new fork?
 
So Van's is telling me... 12 Nose Fork Conversion ?subkit? $325.00 ?contents? WD-01230-1 ?fork? U-01210A-1 ?axle? Doc 12 Man Sect 35 Bag 2847.

Is that everything I need to swap out the old fork and still have the front wheel fairing mount up to the new fork?

Jim,

If you have nose wheel fairings installed, then also order the nose wheel fairing conversion kit. You will have to install new brackets on the forward nose wheel fairing. I am in the process of completing that conversion now.

http://vansaircraft.com/pdf/Notifications/Notification-2016-09-21.pdf

Regards,
 
Tom -

I searched Van's part site for Nose Wheel Fairing Conversion Kit with no luck. Do you have PN?
 
Here's a picture of a failure

This one happened with about 700 hours (on the second fork - first one cracked too). I know the pilots and they are careful - though there will always be the occasional less than perfect landing. Our runway is a bit of a washboard too - it is finally getting fully repaved in October. The triggering action for this break was a slow taxi sharp turn. That was it. I was a pax in the plane at the time.

After this break they put on the beefed-up fork with no further problems.

This fork was inspected (but not with dye penetrant) just days before the failure. Warning: I made the picture HUGE so you could get a good look at the failuer point. There was a similar crack starting at the bottom left weld as well and it was very hard to detect.

IMG_7922.jpg
 
Last edited:
A couple things:
- For The nose fork wheel pant "upgrade" part number isn't available through the Van's web store, but if you call them, it's $20 and is essentially a couple new brackets and hardware.

- The dye penetrant kit will last for many uses, so don't get sticker shock at the initial price. I have a kit over 5 years old and still going; I believe the shelf life was something like 10 years.

- I agree that it's unreasonable to expect "all my landings are greasers". Thanks for posting photos of your cracks. I haven't flown mine yet, but based on this, I'm going to plan to swap out the fork at my first annual. I agree with others that the cost of ~$350 for both the fork and pant hardware is a good insurance policy.
 
Picture

Here are the two upgrade kits. The blue bracket parts on the right are the wheel fairing kit needed to adapt the nose wheel fairing to the new fork.
i-hDj8CPf-L.jpg


This fork is one beefy hunk of metal alright. Some have said it is ugly, but it looks good to me; I like it. It will be inside the fairing anyway most of the time.

I notice that the design of the axle has been changed so the axle bolt can now be torque tightened without danger of over-tightening the pressure on the wheel bearings. The wheel is kept centered in the fork by 2 wavy washers on each side. Nice change.
 
Tony

Is the adapter kit for the fairing non - intrusive as to not disrupt a painted plane/fairing ?
 
Tony, thanks for the quick reply and photo. That doesn't look so bad to me. I think I could live with it. Didn't know what to expect with the earlier negative comments. Mine is fine so far but I may just go ahead and replace it anyway. Why take a chance?
 
Tony

Is the adapter kit for the fairing non - intrusive as to not disrupt a painted plane/fairing ?

Yes, I think that is the case. You have to remove the existing CCR-264SS-3-2 rivets and replace theU-00006A right and left brackets. These rivets are not visible when the rear part of the fairing is installed. See 36A-09, Figure 2.

I haven't completed this yet so that's unverified right now, but it looks easy :rolleyes:.
 
fracture surface

Has any one examined the fracture surfaces? Is there fatigue or is it all static overload? In post 48, I suspect that the strut failure is after the fact. In post 78, I see 45 degree shear lips and possibly some striations, but the photos are not sufficent. 45 degree shear lips are consistent with static overload and striations, if present, would be consistent with fatigue.

If there is no fatigue, then we are likely looking at static overload. The part may have failed under a single load.

If there is fatigue, there was an initiating event and the crack continued to grow. The question is how fast would it grow and how often would you need to inspect once the crack started. If this is a fatigue issue, you may be missing a very small crack that at some point grows very rapidly, under small loads.

In post 78, the crack at the tow bar bolt puzzles me. Why would uploading on the wheel introduce a crack above the tow bar bolt?

Does anyone have good photos of the fracture surfaces? Has anyone opened up the fractures?
 
Another Nose Fork

I removed my wheel pants over a year ago just to be able to look for a nose gear crack prior to each flight (and after) My RV 12 was one of the first ten built (2009) and now has close to 900 hours of landings.

I flew from North Texas to Norman Oklahoma yesterday and back. After returning I found a crack exactly where the lower circle is on SB 16-05-23. It was NOT there when I left Norman. I have always used virtually full-stall landing techniques and never on unimproved strips.

I was debating if it was a function of poor landing technique, hours or just poor design. Still don't know for sure of course but my greatest fear was ripping off my prop so I was anal about checking it. That part worked out.

Keep on eye on yours.
 
Tom,
I'm with you on this. I took my wheel pants off and put on a couple of hubcaps. When I decide to go on a 400+ mile trip, I'll put them back on but for all the local stuff, those huge puppies are staying off. Some may disagree, but Im not seeing a lot of difference between hubcaps and wheels pants. There is no doubt the pressure recovery wheel pants are more efficient, but not as much as you would think. Especially for local stuff.

Hey Craig, Where did you buy your nose wheel hub caps? I think I may give them a try myself.
 
I removed my wheel pants over a year ago just to be able to look for a nose gear crack prior to each flight (and after) My RV 12 was one of the first ten built (2009) and now has close to 900 hours of landings.

I flew from North Texas to Norman Oklahoma yesterday and back. After returning I found a crack exactly where the lower circle is on SB 16-05-23. It was NOT there when I left Norman. I have always used virtually full-stall landing techniques and never on unimproved strips.

I was debating if it was a function of poor landing technique, hours or just poor design. Still don't know for sure of course but my greatest fear was ripping off my prop so I was anal about checking it. That part worked out.

Keep on eye on yours.

And I?m going to go down a bumpy road here, but ?full stall? may not be best practice in the -12 (or any other A Van?s model). I try to land on the mains with enough speed to keep the nosewheel off the ground and let the nose settle as airspeed decreases thru ?stall? speed. I rely on AOA to start the initial beeps as the mains settle in and keep steady backpressure on the stick. Enough to keep the nose flying until it runs out. More of a softfield technique.

I am fairly consistent aside from strong xwinds when I get all 3 down in short order for directional control and stronger braking.

415 hours when we pulled the original nosefork off and replaced with the new version. No signs of any cracks. Replacement was purely preemptive.
 
And I?m going to go down a bumpy road here, but ?full stall? may not be best practice in the -12 (or any other A Van?s model). I try to land on the mains with enough speed to keep the nosewheel off the ground and let the nose settle as airspeed decreases thru ?stall? speed. I rely on AOA to start the initial beeps as the mains settle in and keep steady backpressure on the stick. Enough to keep the nose flying until it runs out. More of a softfield technique.

I am fairly consistent aside from strong xwinds when I get all 3 down in short order for directional control and stronger braking.

415 hours when we pulled the original nosefork off and replaced with the new version. No signs of any cracks. Replacement was purely preemptive.

Yeahhh...would never presume to tell another pilot how to land his aircraft. Simply trying to say cracks may be in everyone's future regardless of how they land. I'm sure there will be more postings of cracked forks. Hopefully, everyone is paying close attention or taking preemptive action as you did.
 
Isn't piece of mind worth 300+ dollars to protect a huge investment? I had to ask. The RV 12 is such a great machine and it is possible that a hard landing is in your future. Even though it is a lot of money, I couldn't stand worrying about a fork failure every time I flew. Just food for thought.
 
Isn't piece of mind worth 300+ dollars to protect a huge investment? I had to ask. The RV 12 is such a great machine and it is possible that a hard landing is in your future. Even though it is a lot of money, I couldn't stand worrying about a fork failure every time I flew. Just food for thought.
For me it is, I have the new fork in stock now.
 
I could name several AD's where only a couple planes in the fleet showed a specific problem. That's how it works in the certificated world. We fix them all. Making a statement that most are OK negates the investigation to some extent.

IMO it really doesn't matter if no one saw the problem if it's my airplane that breaks. I want to know why.

This problem is no different than putting different gear boxes in Cessna AC like the 182 180 and such due to there use not intended in the original AC.
They were added by those who needed them for the rough use. I also agree with Scott about ADs everything doesn't get one much depends upon safety of flight and what the cause of falure was. Boyd.
 
This problem is no different than putting different gear boxes in Cessna AC like the 182 180 and such due to there use not intended in the original AC.
They were added by those who needed them for the rough use. I also agree with Scott about ADs everything doesn't get one much depends upon safety of flight and what the cause of falure was. Boyd.

It appears the original fork is failing under normal use. You can?t buy the old fork any longer AFAIK. So no. It?s not the same.
 
Back
Top