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04-20-2014, 11:23 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by NASA515
"Without Facts and Data, you are just another person with an Opinion."
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Applies to all of us equally.... 
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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04-21-2014, 11:03 AM
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Join Date: Sep 2010
Location: Redlands, Ca.
Posts: 1,458
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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... 
__________________
Allan Nimmo
AntiSplatAero.com
Innovative Aircraft Safety
Products, Tools & ServicesInfo@AntiSplatAero.com Southern California (KREI)
RV-9A / Edge-540 
(909) 824-1020
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04-21-2014, 11:22 AM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by PerfTech
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... 
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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.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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04-21-2014, 11:48 AM
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Join Date: Nov 2011
Location: Hansville, Washington
Posts: 536
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Data on flips
Quote:
Originally Posted by rvbuilder2002
Applies to all of us equally.... 
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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
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04-21-2014, 12:00 PM
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Join Date: Nov 2013
Location: Phoenix, Arizona
Posts: 60
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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.
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04-21-2014, 12:14 PM
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Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,573
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PLUS 1
+1
Quote:
Originally Posted by AV8AZ
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.
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extra characters
__________________
Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet"
Hobbs 625
LS6-15/18W sailplane SOLD
bought my old LS6-A back!! 
VAF donation Jan 2020
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04-21-2014, 12:24 PM
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Join Date: Nov 2013
Location: Prescott, AZ
Posts: 1,614
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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.
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04-21-2014, 01:08 PM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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Unfair
Quote:
Originally Posted by NASA515
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
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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.
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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04-21-2014, 01:55 PM
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Join Date: Oct 2005
Posts: 58
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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.
__________________
Doug Kronemeyer
N972DK
RV-8A
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04-21-2014, 07:04 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Long post alert....
Quote:
Originally Posted by NASA515
As I was fond of saying during my working years - "Without Facts and Data, you are just another person with an Opinion."
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Quote:
Originally Posted by NASA515
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.
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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) point s 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!
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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