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RV-6A nose gear with Anti-Splat device fails

... This thread in definitely inappropriately named and tends to mislead one that perhaps is not well informed on the nose gear issues and its shortcomings. A far more accurate title or name as it were would be Anti-Splat-Nose-Job performs perfectly as designed and most assuredly prevents another flip over. The aircraft in question would most likely have wound up on its back like all the others were it not for the installed nose job. I am relatively certain that if all circumstances of this incident were as stated previously in this thread, that the culprit here will be the tapered bearings locking up. This is akin to landing with the front brakes locked up if it had brakes! All required to verify this possibility would be inspect the outer surface of the mushroom spacers and see if they are galled against the fork surfaces. There have been reported to us, a few mishaps where nose gears have been bent back from striking objects, coyote, dog, traffic cone, large gofer hole and a few others. In every case the gear leg was bent back (Not rolled up like a spring) and only one sustained a propeller strike and that was the coyote not the ground. None of these resulted in a flip-over situation or an injury of any kind (to the occupants). We think this speaks volumes as to the viability of our products and services.
... Previously in this thread there was expressed a desire to create a data base on nose gear failures. I think this is a monumental task, as virtually every one of these incidents is somewhat unique to itself. The variables are almost infinite and this being the case I am not sure how beneficial the information will prove to be. At any rate, we will provide our input deemed useful to this effort. Thanks, Allan
 
Kind of like your thread on "service bulletin fix" that you refused to correct when asked by numerous people.

Just sayin.
Mark

I agree with Allan.

If you examine all reports of tip over on this forum almost all occurred at very low taxi speed after the aircraft pitches up, for whatever reason.

Clearly the front wheel is locking up due to the bearings jaming

In regards to the effectiveness of the Antisplat brace you only have to look at recently posted pictures of an off landing tip over of an RV6 where the nose leg is bent at the top socket not the usual 8 inches up from the fork
 
Did the gear fail?

Was there an Anti-Splat device installed?

If the answer to these two questions is yes then there is no mis-information in the title. Whether it was the "fault, or failure" of the device is certainly up for debate, and should be debated. From what little I know the device may have saved the guy a concussion, or worse. Or it could be that all this device does is move the failure point. I personally don't have a clue, or the engineering knowledge to figure it out.

I am simply bringing it back to his attention that he also inappropriately named a thread because only the manufacturer (Vans) can "Fix" a service bulletin. He had ample opportunity, and multiple requests to fix it and did not. Seems hypocritical to then complain about this title.

That is my only point.
Mark
 
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In civil discourse, it might be best to leave the word hypocritical out of any sentence. There are other places for arguments, just ask my wife.
 
I agree with Allan.

If you examine all reports of tip over on this forum almost all occurred at very low taxi speed after the aircraft pitches up, for whatever reason.

Clearly the front wheel is locking up due to the bearings jaming

In regards to the effectiveness of the Antisplat brace you only have to look at recently posted pictures of an off landing tip over of an RV6 where the nose leg is bent at the top socket not the usual 8 inches up from the fork

Are not many (or most?) tip overs on unpaved surfaces? Suppose the front wheel locked up due to bearings jamming or whatever reason. Would not the unpaved surface be of less friction than a paved surface? Seems to me the unpaved surface would allow for the locked up tire to slide in the dirt, grass, whatever easier than on pavement.
I am not berating the Antisplat brace; I purchased one for our 9A. Just seems to me a locked up wheel is an unlikely culprit on grass.
 
If you examine all reports of tip over on this forum almost all occurred at very low taxi speed after the aircraft pitches up, for whatever reason.

Clearly the front wheel is locking up due to the bearings jaming

Since previously some of this discussion has included talk about maintaining perspective, I offer the following (Peter, this comment is not negatively directed at you, it is mentioned on a regular basis by many people, but you just happened to mention it at this moment).

A lot of the reports and discussions on this forum regarding incidents/accidents are based on first hand (or second or third or...) personal accounts of the pilot flying, or people riding in the airplane involved. Sometimes even witnesses on the outside.
In this day and age where so many RV's have some type of EFIS system that records flight parameters, it is easy to plot on graphs and review what happened leading up to and during an entire accident sequence.
With data that includes pitch attitude, pitch rate, g loads, VSI, ASI, ground speed, heading, (etc., etc.) you can get a very clear picture of what really happened.
I have been involved in reviewing a number of these.
It is rare that the personal account matches very closely to what the data shows happened. In most cases I don't think it is intentional deception, but it is the way it is. Incident/accident investigators have know this for decades.

What is my point?
It usually takes a lot more than asking the person involved, to find out what really happened.
 
I agree with Allan that collecting data on nosewheel failures/tipovers may be a monumental task... Choosing what data to collect is likely going to be your hardest task. That being said, the thing about "big data" is that you really don't know what you're going to get from it until you've collected it and start analyzing. Just ask Google.

From what i've read about the Anti-Splat device, I understood that it would prevent tip-overs by removing the tendency for the gear to fold under... But that it wouldn't necessarily prevent a collapse in some situations. It sounds like it did what it was expected to in this situation.
 
Since previously some of this discussion has included talk about maintaining perspective, I offer the following (Peter, this comment is not negatively directed at you, it is mentioned on a regular basis by many people, but you just happened to mention it at this moment)..

No offense taken, good discussion
 
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Allen protrusion

Y'know.....
I don't remember any commentary in any of the nosewheel failure threads about the length of the big allen screws on the newer designed fork. If one follows drawing C1 exactly (which applies to RV7, 9 and maybe others) and use the supplied parts, you wind up with two big bolt ends pointing right at the tire sidewall and very close to touching. It the tire bulges at all, it is a real risk of catching the tire.

I put 4 washers under the heads of mine (1/4" total) such that the bolt ends are flush with the inside of the fork. I hope others are doing the same, and ignoring what drawing C1 says to do.
 
I will share my totally unqualified opinion simply as someone who was going to build a nose dragger, contemplated the ASA modifications, and ultimately decided to avoid the entire debate. Take it for what it's worth, which is every penny you're paying for it. For the record, this is not me saying "tailwheels rule", nor is it me saying the ASA modification is either good or bad.

It seems to me that with or without the Anti-Splat modification(s), physics don't change. If an event occurs that would fold up the unmodified nose gear, there's a really good chance it's going to fold up the modified nose gear as well. If all you do is move the point of failure from the bottom to the top of the gear leg, at least you may have turned a prop strike and back flip into just a prop strike. If that's the case, there's a net gain that would justify the cost and effort of making the modification.

I'm no mechanical engineer, although I was raised by one. Knowing the history of the RV nose gear, it seems to me that changing the gear leg and/or mount to give more of a tendency toward vertical deflection and less toward horizontal deflection might have some positive results. Looking at other designs (Cirrus, Grumman) shows how other designers have done it. After reading discussions like this for a couple of years, I still can't figure out for sure if proper pilot technique can guarantee no incidents, or not. Although this issue was not the only influencing factor, I did decide to opt out with an RV-7 - so now I'll butt out.
 
From what i've read about the Anti-Splat device, I understood that it would prevent tip-overs by removing the tendency for the gear to fold under... But that it wouldn't necessarily prevent a collapse in some situations. It sounds like it did what it was expected to in this situation.


My understanding as well. This incident has not dampened my confidence in the Nose Job; quite the opposite for exactly this reason. No one can provide guarantees, but I feel like the package of mods provided by AntiSplat (and I have them all) mitigates the risk to the greatest extent possible, both in terms of preventing an incident in the first place and minimizing damage and injury if a gear failure does occur. This package and my helmet is all I can do!
 
Data Collection

Data collection appears to be a fairly significant task but I think it will start. I received an offer to help from Tony Sorce (tsorce on VAF) and between the two of us we've come up with a fairly lengthy list of data we'd like to collect on these accidents. So before we start, I'd appreciate any constructive suggestions on what we're looking at in terms of relevant data. Are we missing anything important that we should add? Are there data that we're collecting that we don't need?

Before anyone says anything, I realize this is pretty optimistic and we won't get all the data we seek, especially on tip-overs that are history. However, we'll get what we get and see where it takes us. I will also be contacting Scott (rvbuilder2002) and Alan (PerfTech) to get their input and thoughts but to the extent that it's possible, I want the data to drive this process.

And finally, neither Tony nor I want to embarrass anyone. Pilot skill may or may not play a part, and even the best pilot can have a bad day. So to the extent practical we'll keep the N-numbers and pilots names to ourselves. Obviously, many of the records are public already, so I'm not promising anonymity - just to be clear.

And along the same lines, both Van's Aircraft and Anti-Splat Aero, to the very best of my knowledge produce well engineered products. I'm not here to besmirch anyone or any company. FWIW, I'm flying a 9A and building a 9A - and I've landed on grass, albeit not a lot. Currently I don't own any of the ASA products but in time, I likely will.

My intent is to figure out what causes these events and what can be done to avoid them or at least reduce the odds of them occurring. After talking to Tony this morning I believe heis in this for the same reasons but I'll let him speak for himself.

So with that introduction, here's what we've come up with. It's D-R-A-F-T 1.

Incident Number (1, 2, 3, etc.)
N-number
Model 6A/7A/8A/9A
Yr of Incident
Data Source, VAF, NTSB, etc
Man. Year
Engine O-320, O-360, etc
Prop Wood, metal, composite, and FP, CS,
Fork Mod
Wheel Bearing Stock, ASA, Beringer, Matco, other
ASA Nose Job
ASA Lip Skid
Runway Surface Grass, and comments on condition
Failure Mode Bent gear, Nose over, Prop Strike
At Time of Incident
Speed
Flap Position
Braking?
Stick back?
Pilot Information
Name
Total Hours
Hours in Type
Hours non-paved
Photo, Video ref. (folder, name, etc)
Comments


Thanks in advance for any comments and suggestions....and yes, I understand there's not promise that the data will prove anything but hopefully we'll get a better handle on the numbers of these incidents and hopefully learn something. If not, well I worked for government once and this won't be my first waste of time.<g>
 
Y'know.....
I don't remember any commentary in any of the nosewheel failure threads about the length of the big allen screws . . . .

This is what online forum 'discussions' have done to me: my mind is spring loaded to expect a fight. I read the title for you post (Allen protrusion) and I thought you were going to comment negatively on Allan's insertion into the discussion with his comments in post #51! :p
 
Data collection appears to be a fairly significant task but I think it will start. I received an offer to help from Tony Sorce (tsorce on VAF) and between the two of us we've come up with a fairly lengthy list of data we'd like to collect on these accidents. So before we start, I'd appreciate any constructive suggestions on what we're looking at in terms of relevant data. Are we missing anything important that we should add? Are there data that we're collecting that we don't need?

Before anyone says anything, I realize this is pretty optimistic and we won't get all the data we seek, especially on tip-overs that are history. However, we'll get what we get and see where it takes us. I will also be contacting Scott (rvbuilder2002) and Alan (PerfTech) to get their input and thoughts but to the extent that it's possible, I want the data to drive this process.

And finally, neither Tony nor I want to embarrass anyone. Pilot skill may or may not play a part, and even the best pilot can have a bad day. So to the extent practical we'll keep the N-numbers and pilots names to ourselves. Obviously, many of the records are public already, so I'm not promising anonymity - just to be clear.

And along the same lines, both Van's Aircraft and Anti-Splat Aero, to the very best of my knowledge produce well engineered products. I'm not here to besmirch anyone or any company. FWIW, I'm flying a 9A and building a 9A - and I've landed on grass, albeit not a lot. Currently I don't own any of the ASA products but in time, I likely will.

My intent is to figure out what causes these events and what can be done to avoid them or at least reduce the odds of them occurring. After talking to Tony this morning I believe heis in this for the same reasons but I'll let him speak for himself.

So with that introduction, here's what we've come up with. It's D-R-A-F-T 1.

Incident Number (1, 2, 3, etc.)
N-number
Model 6A/7A/8A/9A
Yr of Incident
Data Source, VAF, NTSB, etc
Man. Year
Engine O-320, O-360, etc
Prop Wood, metal, composite, and FP, CS,
Fork Mod
Wheel Bearing Stock, ASA, Beringer, Matco, other
ASA Nose Job
ASA Lip Skid
Runway Surface Grass, and comments on condition
Failure Mode Bent gear, Nose over, Prop Strike
At Time of Incident
Speed
Flap Position
Braking?
Stick back?
Pilot Information
Name
Total Hours
Hours in Type
Hours non-paved
Photo, Video ref. (folder, name, etc)
Comments


Thanks in advance for any comments and suggestions....and yes, I understand there's not promise that the data will prove anything but hopefully we'll get a better handle on the numbers of these incidents and hopefully learn something. If not, well I worked for government once and this won't be my first waste of time.<g>

This will only be useful if the data is collected into a system that is easy to access (web enabled), controls input, and allows for reporting and data correlation. If there was enough interest, I could do this pretty easily. But I dont want to waist my time on it if there is no interest. A web based survey system to capture the information is what would be required in order for this to be of any use. I have one of these running now that I use for surveying my customers. I could easily create a web based survey to capture and report this type of stuff.
 
Thanks in advance for any comments and suggestions....<g>

You need weight on nose gear.

Sort of know if extra weight there based on engine/prop combo but since Van released a SB on keeping weight down on Nose and it is one of the major forces on the gear I think is is very useful information.
 
Some more data you could also collect:

approx. total aircraft weight at time of incident. ie passengers, baggage fuel etc

approx. CG of aircraft at the time of the incident

tire pressure

wheel pants on/off

previous damage history

total hours on aircraft

Grove wheel as another bearing type

nose gear leg re-enforcement type if any, wood, fiberglass, other
 
This will only be useful if the data is collected into a system that is easy to access (web enabled), controls input, and allows for reporting and data correlation. If there was enough interest, I could do this pretty easily. But I dont want to waist my time on it if there is no interest. A web based survey system to capture the information is what would be required in order for this to be of any use. I have one of these running now that I use for surveying my customers. I could easily create a web based survey to capture and report this type of stuff.

OK in an effort to support the nose wheel data collection, I have put up a test survey that can be used to collect the data. This is just a sample of what can be done. All the data can be ported out in a number of formats for analysis. Feel free to play around with it. Submit any number of samples that you would like. After you go though it, let me know if there is something you would like in there. Given the very few number of incidents, more info is probably better. This is JUST a test survey. After you all play with it, and we get the elements correct, I can create a production survey. I would really like someone with FMEA experience to chime in. Once a production survey is created, you can not add or delete elements. But I can easily change the information that is placed in any element afterwards. I made some fields mandatory, some optional. I have no idea to what end any of this would be really useful, but... here you go.
http://teamaerodynamix.com/survey/index.php/279266/lang-en
 
Survey

Mike,
Thanks for taking the initiative in creating the survey. You have clearly given it some thought. I haves filled out the survey and offered ideas for updates in the comment boxes.
I suggest that the readers should sign in so we know the audience. This can be done via the forum sign in or otherwise.
I suggest that we understand any insurance aspects as we create the base.
Also statistically the number of failures is small, even though one is enough if it is yours. We need to be knowledgeable about handling the statistics when the analyses are done. First person accounts are not always reliable and even outside observers can be suspect.
 
Survey

Thank you Mike. Its a start and we have to start somewhere. The Anti-Splat brace is brilliant in it's simplicity and does what it was designed to do,without the wheel-bearing mod its limited in effectiveness.Perhaps Allan should only sell the brace with the bearing modification,make it a package deal with a better price.How about a deal with Vans through the catalog.I love the Warren Buffet comment and can't help but to think,tail wheel,no steps,less weight, less expense,grass strips. I'm committed to the nose wheel and like others need an answer as to there and my safety.
RHill

Sorry Sam,It comes out of frustration over this issue. Note to all,Please disregard above as personal opinion,not fact.
RH
 
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....The Anti-Splat brace is brilliant in it's simplicity and does what it was designed to do, without the wheel-bearing mod its limited in effectiveness....

Careful......don't taint the survey with your conclusions before the data is submitted!

See, that is the problem....everybody already has their own bias... ;)
 
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My experience.
9A with hundreds of trouble free landings on my less than perfect grass strip plus various other grass strips. My strip is hard on the nose gear as it is short and the nose wheel usually has to be lowered to the ground prematurely followed by moderate to heavy braking.

IMHO the nose wheel assembly will take just about all the abuse you can throw at it provided the nose cone does not contact and catch on the ground.

I believe the most important modification I have done is to install the newer (2007) style fork and strut with the extra 1" ground clearance followed by fibreglass surgery to raise the lower surface of the nose cone to utilise that extra inch clearance.

Fin
9A
 
Rhino surgery !

followed by fibreglass surgery to raise the lower surface of the nose cone to utilise that extra inch clearance.

Any chance of elaborating on that statement a little Fin and maybe a photo of your modification. :confused:
I figure if you have the newer gear with extra inch clearance, the "Nose Job",
the "Skid Plate" and practice good landing technique , you've done about all you can to lessen your chances of a forward ground loop. :)
 
I never liked the strut and nut being so close the the ground and when the lip skid came out I got it right away. I think that alone is huge. If I didn't have foam on my strut I would do the rest but just can't get myself into that much work right now. I really don't know how to clean it off. Allen never said his unit was 100% right away but it was going a long way to help in many conditions. Don't expect a silver bullet.
 
Survey Data

Thanks Mike, I got a lot from your post, it’s great to see we're on the same page. It's important to make the survey structured and easy to use. Don and I were planning to use a similar product from Google Forms. We wanted to wait a few days to continue to get input from you all on this thread before launching a new post with the survey question program link. Data will be coming from other sources i.e.: NTSB, pilots, old reports that will have to be filtered in, etc. I see the goal as collecting all the data we can and presenting it in an easy to use/access format. After that we can talk about the next steps but I believe most people will look at the data for themselves and decide what is important to them. We hope to roll it out mid week.
Mike, Bevan, Philip, RH, Sam - thanks for all the input, keep it coming.
Tony
 
With regard to data collection, I'm assuming everybody has seen and read the NTSB Special Structures Study on RV-6A thru -9A nose gear failures and resultant airplane flips. They analyzed 19 events in 2007. The study can be found here:

http://www.ntsb.gov/doclib/reports/2006/rv_study.pdf

Getting a special NTSB Study is not something most manufacturers or airplanes will ever see - there have been quite few over the years - ATR42 Icing Problems, Learjet 23 High Speed Dives from Altitude, Mitsubishi MU-2 training requirements, and the Zenith Flutter and Wing Failures have been some. To get such attention means there have been a sufficient number of events for the situation to poke its head above the background noise. Recognizing also, that those events may have represented configurations no longer being produced or in service.

Just casually, it does seem some of the changes - including Alan's device - have been effective to some degree - maybe also due to awareness and training - in that the number of flips seems to have receded from where it once was. As some have pointed out, a nose gear failure and/or fold-back is much superior to having a flip.

With regard to the -12, as I and others have pointed out in previous threads, one significant difference is it has a much larger nose wheel - same size as the Mains. Helping a friend build his -9A, I was always stuck (shocked?) by the small nose wheel on what was a much larger airplane.

I follow -12 accidents quite closely, and there have been - to my knowledge - no flips. Yet, there have been several accidents that would seem to be flip candidates - a good sign.

Bob Bogash
RV-12
N737G
 
To get such attention means there have been a sufficient number of events for the situation to poke its head above the background noise.

Or, someone from the FAA/NTSB is personally connected with the airplane involved in the accident that initiated the investigation... as was the case in this instance.

Because of that, it would be expected that some level of fault with the design would come out in the report, but if I remember correctly, there was no smoking gun specified in the report.
 
And the other 18 events cited in the report? Also friends of the NTSB investigator?

As I recall - perhaps faulty memory - but the number of total flips is considerably larger than the 18 cited in the report. Maybe double. Maybe more. Alan has created a business around solving the problem - assuming there IS, a problem......

A google search of the Chris Heintz "letters of denial" to affected Zenith operators after the NTSB was the last - not the first - national investigating authority to point a finger at a flutter problem - resulting in an FAA grounding order. To Chris, there never was a problem - his design was as solid as the Rock of Gibraltor - despite overwhelming data indicating otherwise. I'm sure he still feels that way to this day.

Others in this thread have pointed out the apparent paucity of similar flips in other tricycle gear airplanes in similar situations. But, in the end, Facts and Data will determine the truth of the matter. To that end, the nascent data collection effort current being started, will be a big step forward. As I was fond of saying during my working years - "Without Facts and Data, you are just another person with an Opinion."

Bob Bogash
RV-12
N737G
 
Fair Shake for RVs!!!!!!

..... I am somewhat of the opinion that the RVs have not necessarily gotten a fair evaluation in the accident department. Granted, there have been more than a few of these gear involved accidents involving our A-models, but in all fairness one needs to look at a few other facts. The sheer numbers of RV-A models are somewhat staggering as compared to any other small, fast, sporty and well used aircraft. Add into this equation the very small wheels and tires, wheel pants (close to the ground), a less than robust gear leg, the fact that a very large number are operated off grass and dirt strips. Add also the fact that many of the pilots are low time or at least new to this type of airplane as well grass fields. Imagine if you will, What the statistics would look like if Lancairs, Cerrises, Glassairs and a few others were out there in the same quantities as RVs. Now imagine if they were proportionately operating off grass as the RVs do. I believe the numbers would be so ridiculous, the funeral dates would be conflicting with one another. Also the powers that be would launch a campaign to outlaw small aircraft altogether. We as RV pilots and owners sometimes can be over critical of our machines as they are almost like a family member in that anything short of perfection in unacceptable. There will always be gear collapses on airplanes and that can't be totally eliminated. We had six at my home airport, on blacktop in just two years and all were commercially produced spam cans. If we can just change the dynamic of the failure to not produce a flip-over event them huge strides in safety have been accomplished. As a relatively well organized community, I feel we have all stepped to the plate on this in unprecedented numbers, looked at it, micro analyzed it, offered up opinions and you name it, many good and some not so good. In my forty odd years in aviation, I can't recall an equal effort by any group of aviation enthusiasts that even begins to compare. When looking at the big picture, as bad as the numbers seem I really don't think them that out of line when all is considered. Thanks, Allan...:D
 
When looking at the big picture, as bad as the numbers seem I really don't think them that out of line when all is considered. Thanks, Allan...:D

Agreed.

One other thing you did not mention-------number of landings/fleet.

I suspect the RV fleet is seeing more use than any other homebuilt.

Remember, one accident makes a headline, while a thousand safe landing do not.
 
Data on flips

Applies to all of us equally.... ;)

In that spirit, Scott, why don't you share with us the Vans database on flips across the fleet - -6 to -12, -A models and taildraggers, with data on gear config (if applicable), grass vs paved, speeds involved, chuck holes, washboards, and the rest of the known parameters that VAF members are trying to ReCreate as a spreadsheet on another thread in the Safety section.

I feel certain that Vans receives data on 95% plus of significant accidents and probably studies them at length, in addition to participating in many of the formal investigations. Analysis of the data would certainly put some of the demons to rest.

For starters, just how many RV's are known to have flipped?

It certainly seems a shame that folks are trying to recreate something that likely already exists.

Bob Bogash
RV-12
N737G
 
I genuinely do not mean to cast aspersions, but this discussion is remarkably similar to the Matronics zenith forum discussions about the 601XL back when it was having issues. The Matronics zenith list is still up to read what I'm referring to.

In both cases, a suspected problem called at least part of the designs into question. Both cases were designed by quite prolific homebuilt aircraft designers. Both designers had thousands of their designs flying all over the world. Both designers had innumerous supportive enthusiasts quick to jump to their support. The supporters disproportionately blamed either suboptimal construction techniques, suboptimal maintenance techniques, or simply pilot error. Neither manufacturer willingly undertook their own individual effort to fix the problem. One pointed to the "absence of a smoking gun" openly, the second apparently not openly. Both discussions intermittent went "philosophical" asking all involved to not get hysterical and instead to look at the bigger picture suggesting that the failures were commensurate with industry standards "if you think about all the numbers and stuff."

Critical airframe parts are designed to work reliably under approved conditions. If the part fails under approved conditions then there is a design problem. One failure is one too many. The problem indeed could be in suboptimal construction or maintenance, but, for structures designed to be manufactured and maintained by amateur builders, historically designs took this into account.

I otherwise still own an C-150 and I am at a loss to recall ever hearing of any nose gear collapses on rollout or during a taxi phase in a 150. RVs have nowhere near the fleet or abuse history of the 150. This isn't about giving RVs a bad name...RVs have been the new lifeblood for GA for decades. This discussion is about frankly trying to fix a problem that the factory isn't addressing.
 
PLUS 1

+1

I genuinely do not mean to cast aspersions, but this discussion is remarkably similar to the Matronics zenith forum discussions about the 601XL back when it was having issues. The Matronics zenith list is still up to read what I'm referring to.

In both cases, a suspected problem called at least part of the designs into question. Both cases were designed by quite prolific homebuilt aircraft designers. Both designers had thousands of their designs flying all over the world. Both designers had innumerous supportive enthusiasts quick to jump to their support. The supporters disproportionately blamed either suboptimal construction techniques, suboptimal maintenance techniques, or simply pilot error. Neither manufacturer willingly undertook their own individual effort to fix the problem. One pointed to the "absence of a smoking gun" openly, the second apparently not openly. Both discussions intermittent went "philosophical" asking all involved to not get hysterical and instead to look at the bigger picture suggesting that the failures were commensurate with industry standards "if you think about all the numbers and stuff."

Critical airframe parts are designed to work reliably under approved conditions. If the part fails under approved conditions then there is a design problem. One failure is one too many. The problem indeed could be in suboptimal construction or maintenance, but, for structures designed to be manufactured and maintained by amateur builders, historically designs took this into account.

I otherwise still own an C-150 and I am at a loss to recall ever hearing of any nose gear collapses on rollout or during a taxi phase in a 150. RVs have nowhere near the fleet or abuse history of the 150. This isn't about giving RVs a bad name...RVs have been the new lifeblood for GA for decades. This discussion is about frankly trying to fix a problem that the factory isn't addressing.

extra characters
 
When I was a student 41 years ago my flight school owner said go ahead and land on the Tripacer nose wheel. His competition had gone to 150's. Yes, they broke them.
 
Unfair

In that spirit, Scott, why don't you share with us the Vans database on flips across the fleet - -6 to -12, -A models and taildraggers, with data on gear config (if applicable), grass vs paved, speeds involved, chuck holes, washboards, and the rest of the known parameters that VAF members are trying to ReCreate as a spreadsheet on another thread in the Safety section.

I feel certain that Vans receives data on 95% plus of significant accidents and probably studies them at length, in addition to participating in many of the formal investigations. Analysis of the data would certainly put some of the demons to rest.

For starters, just how many RV's are known to have flipped?

It certainly seems a shame that folks are trying to recreate something that likely already exists.

Bob Bogash
RV-12
N737G

Bob, no matter how we would all like to have that data, it is probably not Scott's to give. I have no idea who you work for (or worked for), but unless you were the president and owner, as an employee, you probably didn't have the authority to give away company data on your own volition.

Scott contributes here voluntarily, and clearly states that his comments and opinions are not necessarily that of his employer. He is a huge fount of information. If you call him out publicly on stuff he can't give, and he gets upset, he leaves - and we are all the poorer for it. If you want to be known as the guy that chased Scott away from the forums, so be it.

I personally woudl beleive that while Van's has a lot of information and data, it is no more "complete" than anyone else's database. I know of lots of aircraft mishaps that were never reported to anyone other than the few guys who helped cart the wreck off the field and into a hangar. Enough to skew anyone's data.

Oh, and I know at least two people who have collapsed C-150 nose gears - it does happen.
 
Allan has it right

Allan's brace is working very well. It allows normal flexure of the gear with vertical loads, and engages only with high aft loads. The brace has changed the dynamics of the failure mode, and in what I think is a very benefical way. With out the brace, the gear fails just above the NLG axel, at the gears narrowest point. This failure impulse and bending does not push the nose up, but rather pulls it down rapidly from the friction of the forward yoke with the ground. This drives the nose into a rapid prop contact, which provide the final impulse for the pole-vault event. These two impulses occur within probably only microseconds between them. With the brace, the gear bending point is very close to the engine mount. When the gear folds back, the gear rotation actually pushes up the nose of the aircraft. Once this major impulse event is over, the nose settles on the prop from gravity. The impulse from the prop strike alone is not enough to cause the pole vault event. Seems like a better failure mode to me.
 
Long post alert....

As I was fond of saying during my working years - "Without Facts and Data, you are just another person with an Opinion."

I feel certain that Vans receives data on 95% plus of significant accidents and probably studies them at length, in addition to participating in many of the formal investigations.

Well Bob, you may no longer be in your working years (though some of your posts I have seen, describing what you stay busy with in your retirement years makes it seem like you still are ;)), but your phrase still applies...

"I feel certain" does not constitute facts and data.
The reality is, Van's doesn't have a big data base of research done on A model flip-over accidents, and doesn't have any more information about most accidents than anyone else does that spent the time looking at what is available in the NTSB reports.

Occasionally, the NTSB requests assistance, but I think most of those instances have been fatal accidents where having someone very familiar with the engineering, and the structures is helpful.

The FAA has requested help with an RV-12 nose gear failure. As a result, some specific static load testing was done on a sampling of nose gear forks. Based on the data from those tests, the data that was acquired from the EFIS system in the accident airplane, and factored with photos of the touchdown (impact) points on a grass runway, they were fully satisfied that the accident was the result of pilot error. As I have already mentioned is most often the case, the pilots account of what happened didn't entirely match up with what all of the other data clear showed happened.

Since the release of the NTSB report you sited (almost 7 years ago now, and Van's contributed data and information to it), I am not aware of them having any interest in having another look at it.

So, in a nut shell, even if I was in a position to provide you with an answer to your questions, I wouldn't have any more data to give credible answers, than anyone else who has spent time researching in the NTSB report (no easy task).

One thing I would like to make clear (and then I am clearing out of this thread)...
I personally own an RV-6A.
I purchased it damaged, as a result of a flip over accident.
The accident was totally pilot error (and listed so in the NTSB final report)
Because of my communications with the original builder / accident pilot, I know some details of the accident that didn't even make it into the report.
So I have my own personal interest in the subject.

I said it once, but I will repeat it again, without some method of data collection outside of the account that the pilot or other witnesses can give, knowing what the actual cause of an accident like this is can be difficult. I am not saying that developing a process to gather data is not worth the effort, just saying that it will be of much less value if something to substantiate the personal account of what happened is not part of the report.

I fully rebuilt the airplane and have been flying it for about 5 years. It is based at an airport with a paved and a grass runway. I probably make 95% of my home base landings on the grass (cheapskate... like to save wear on tires), with the original version nose gear fork <gasp>.

No one at Van's has ever swept this under the rug, as some have been very vocal in proclaiming.
I think the attitude is more along the lines of being realistic (as Alan did a good job of saying earlier). The realistic attitude is that the airplanes are one big engineering compromise... with the goal of attaining the best (ultimate) performance possible.
Could the nose gear be more forgiving. Sure (and since that seems to be a good idea for a lot of the pilot population, the RV-14A was born), at the cost of simplicity and the balance of engineering compromises that exist right now.

As we know, RV's are experimental class airplanes. If an owner decides they don't like the way the different compromises align, they are free to align them a different way.

Comments have been made comparing an RV-6A to a C-150... keep in mind that an average empty weight C-150 (with a stink-en little O-200 on the front) is about the same as a lot of fixed pitch prop RV-6A's.

My personal feelings (as everything in this post is... what I said above is in no way speaking for Van's or anyone else who works there).

If someone has an interest in really getting to the bottom of this, and if they could objectively look through all of the accidents with enough data available to determine in which accidents it was simply a pilot having a bad day (I say if, because in a lot of them it is not possible), and then would focus on what is left, I believe it would look like a much smaller problem.


Over, and out!
 
"I fully rebuilt the airplane and have been flying it for about 5 years. It is based at an airport with a paved and a grass runway. I probably make 95% of my home base landings on the grass (cheapskate... like to save wear on tires), with the original version nose gear fork <gasp>. "

Classic! Thanks for your input to this thread.
Cant stop myself from asking though - I'm guessing you haven't installed the Antisplat nose job either?

Erich
 
Over and out?

But, Scott, you have promised me a beer!

Well said, and I appreciate your perspective. After you buy me my beer, I'm committed to buy you one. In the end, we'll probably have too many beers and still disagree.

Oh well.....

Bob Bogash
RV-12
N737G
 
I have an updated nose gear leg, and installed all the Anti-Splat modifications. I am fanatical about technique on every movement of the plane to keep it light on the nose. I have insurance. I land on grass. I only hope not to tip over, may Forculus, god of the threshold, forever look kindly on my risk mitigation.

Wasn't Forculus the god of doors and Limentinus, god of the threshold?

My third wheel has fallen behind, so it acts differently. Hopefully it will behave.
 
In my field (medicine) it is common knowledge that statistically I personally will cause personal harm to people who I am directly responsible for and may even cause early death in a few, despite my best efforts. We constantly try to mitigate risk and improve. We have a lot of room for improvement. Obfuscation and cult-think have no place in a serious discussion on safety. The first clouds the data and the second clouds the analysis. I might give some people a pass on understanding this, others not so much.

Back to the nose gear. We criticize auto-conversion engine folks for being tinkerers instead of fliers. We remind them that dinosaur technology works. I don't understand the logic of promoting tinkering with the current nose wheel setup when other systems have proven less problematic. If you don't agree with "proven less problematic" then I don't know what to say.

Tyson
PS: I would concede that any aircraft with a nose gear will eventually experience a nose gear failure. The question is about the statistics of the phenomenon. Like the 601XL issue, 'at all cost' designer-supporters seem to maintain a very similar 'no real problem' view. This is probably a dead horse as each reader is in one camp or the other.
 
With regard to data collection, I'm assuming everybody has seen and read the NTSB Special Structures Study on RV-6A thru -9A nose gear failures and resultant airplane flips. They analyzed 19 events in 2007. The study can be found here:

http://www.ntsb.gov/doclib/reports/2006/rv_study.pdf
::

We all have selective reading...
3.0 SUMMARY:
::
The FEA shows that the nose gear strut has sufficient strength to perform its intended function. In all cases, the landing gear struts and forks were making contact with the ground and initiating the damage sequence.
 
Well Bob, you may no longer be in your working years (though some of your posts I have seen, describing what you stay busy with in your retirement years makes it seem like you still are ;)), but your phrase still applies...

"I feel certain" does not constitute facts and data.
The reality is, Van's doesn't have a big data base of research done on A model flip-over accidents, and doesn't have any more information about most accidents than anyone else does that spent the time looking at what is available in the NTSB reports.

Occasionally, the NTSB requests assistance, but I think most of those instances have been fatal accidents where having someone very familiar with the engineering, and the structures is helpful.

The FAA has requested help with an RV-12 nose gear failure. As a result, some specific static load testing was done on a sampling of nose gear forks. Based on the data from those tests, the data that was acquired from the EFIS system in the accident airplane, and factored with photos of the touchdown (impact) points on a grass runway, they were fully satisfied that the accident was the result of pilot error. As I have already mentioned is most often the case, the pilots account of what happened didn't entirely match up with what all of the other data clear showed happened.

Since the release of the NTSB report you sited (almost 7 years ago now, and Van's contributed data and information to it), I am not aware of them having any interest in having another look at it.

So, in a nut shell, even if I was in a position to provide you with an answer to your questions, I wouldn't have any more data to give credible answers, than anyone else who has spent time researching in the NTSB report (no easy task).

One thing I would like to make clear (and then I am clearing out of this thread)...
I personally own an RV-6A.
I purchased it damaged, as a result of a flip over accident.
The accident was totally pilot error (and listed so in the NTSB final report)
Because of my communications with the original builder / accident pilot, I know some details of the accident that didn't even make it into the report.
So I have my own personal interest in the subject.

I said it once, but I will repeat it again, without some method of data collection outside of the account that the pilot or other witnesses can give, knowing what the actual cause of an accident like this is can be difficult. I am not saying that developing a process to gather data is not worth the effort, just saying that it will be of much less value if something to substantiate the personal account of what happened is not part of the report.

I fully rebuilt the airplane and have been flying it for about 5 years. It is based at an airport with a paved and a grass runway. I probably make 95% of my home base landings on the grass (cheapskate... like to save wear on tires), with the original version nose gear fork <gasp>.

No one at Van's has ever swept this under the rug, as some have been very vocal in proclaiming.
I think the attitude is more along the lines of being realistic (as Alan did a good job of saying earlier). The realistic attitude is that the airplanes are one big engineering compromise... with the goal of attaining the best (ultimate) performance possible.
Could the nose gear be more forgiving. Sure (and since that seems to be a good idea for a lot of the pilot population, the RV-14A was born), at the cost of simplicity and the balance of engineering compromises that exist right now.

As we know, RV's are experimental class airplanes. If an owner decides they don't like the way the different compromises align, they are free to align them a different way.

Comments have been made comparing an RV-6A to a C-150... keep in mind that an average empty weight C-150 (with a stink-en little O-200 on the front) is about the same as a lot of fixed pitch prop RV-6A's.

My personal feelings (as everything in this post is... what I said above is in no way speaking for Van's or anyone else who works there).

If someone has an interest in really getting to the bottom of this, and if they could objectively look through all of the accidents with enough data available to determine in which accidents it was simply a pilot having a bad day (I say if, because in a lot of them it is not possible), and then would focus on what is left, I believe it would look like a much smaller problem.


Over, and out!

This is the most important quote of the whole thread, all the "data collecting" everyone is wanting is fine and dandy, but with "pilot technique" in the equation there is no hard data to even remotely determine the causes. I bet out of a sample of 100 nose wheel accidents of any type of airplanes over half the pilots either didn't tell the truth about their error or didn't think they did anything wrong. Just like the RV accident i read on here about a year or so ago, "I brought it in to land and it bounced twice and then the gear collapsed", well OKKKK yeh it collapsed because you porpoised it in and put 10000lbs(or whatever) of force on the nosewheel. I just think there is alot of pilot error involved in a BIG percentage of these accidents and alot of people are wanting to blame the nose gear, but thats just my opinion. And if everyone wants a eye opener(and i am sure you guys have seen), go to sun n fun or oshkosh pull up a chair and just set there for hours watching landings, they will bounce and slam them in all day long. Heck it happens to everyone at one time or another and some pilots WAY more than normal if you catch my drift. Me and my partner are building a RV7A with no nosewheel worries
 
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I purchased a very early 7A kit in 2001. At that time Vans suggested the nose wheel version if you will be flying off of grass as the 7A will get off the grass quicker than the 7. This was actually promoted in their early 7 series literature.
I chose to build the 7A because I had no tail wheel time and I did want to fly off of grass. I completed my 7A and have not yet landed it on grass. A whimp?
Maybe but Vans no longer suggested the 7A is a better choice for grass. They changed their literature! hmmmmm

Did Van really say the 7A would get off quicker than the 7?

I converted my RV7A to a 7.
I can tell you right now the the TW gets off much quicker than my A model did.
I would questimate about 50 feet as I compare it to my windsock.
Unless, he just meant getting the nose wheel off the ground & not flying.

My home base is paved, not grass.
 
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Sure did. if you have the old literature it is there. I recall the their reasoning behind this was the angle of attack of the 7A vs the 7. Maybe it is Pilot technique!
 
The AOA would have no bearing on takeoff. With a tailwheel you can set the AOA at any level you are comfortable with at liftoff. You can even leave the tailwheel on the ground to generate the highest AOA and shortest ground roll. You could try and do that with a nose gear by rotating early but would be within inches of dragging the tail to match the tailwheel aircrafts attitude. There must be another factor at play here.

George
 
I said I was done posting in this thread but since this is a totally different subject...
The A model RV's (particularly the 7 & 9) can rotate to a higher AOA on the ground. The main gear being farther back on the A model, and the lack of tail wheel, makes it possible.
You can check it your self using the scale 3 view of each model.
 
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