The nosegear debate by Bob Collins

(Note: This article was updated on 11/15/06 to include additional data from Van's)

It's the issue that won't go away. From time to time, usually following just about every accident involving an RV airplane, the questions about the strength of the RV nosegear reappear. Is it really an issue? As with most "debates" on Planet RV, it is if you think it is, and it's not if you think it's not.

What the debate usually comes down to is aircraft design vs. pilot performance. Whenever an RV flips over, the various Web sites and bulletin boards feature plenty of chatter about the nosegear design, followed shortly thereafter by a spirited defense of the nosegear, and accusations that pilots are exhibiting poor landing technique.

But what if it's both a "floor wax and a dessert topping?" What if it's a combination of pilot technique and nose gear design. I am completely unqualified to render a verdict and so I choose not to. I am comfortable just documenting the various information that's out there, and you can make your own decision.

Why has this come up again? For me, it's traffic on the Yahoogroup list called "rvsqn." RV Squadron is a very busy e-mail list, and a few weeks ago the nosegear issue came up.

Member Bill Knott contended the nosegear as designed is not sufficient for the U.K.'s abundance of grass strips.

"What I am trying to do is to get into a strip that I have been told is OK for landing, only to have a problem which could become very serious," Bill says. "My original gearleg was supplied by Vans and was correctly made by me. The height of the nut was about 85 mm, say 3 1/2" from the ground unloaded, not allowing for the weight of the engine etc, that is very close. My new installation is considerably better than that in that the unrequired stick out from below the gearleg nut of about 30 mm has been removed and the botton of the yoke has been lifted by 25 mm, making a total increase of height from the ground of 55 mm. If a larger wheel and possibility of a even larger(wider) tyre can be fitted into my aircraft by using only a new yoke, as done by others aircraft, the safety angle must improve for all but the wettest ground. "

OK, let's back up and take a look at the issue.

The earliest concern I've heard voiced about the "beefiness" (or lack thereof) of the nosegear on an RV was August 1998.

I've personally seen a gear failure in a -6A...the nosewheel strut folded near the wheel fork during a rather stiff crosswind arrival. We could beat this one to death...and probably never come up with a "fix" for it. It is a proven, viable design, and the odds just happened to stack up against the pilot of this aircraft on that day. (The plane is fine, no prop strike, no other issues). I don't think Van...or any designer, for that matter, can design an airframe that will survive any and all possible encounters in the flight environment. There will always be some unknown elements in each flight profile...clear air turbulence, sudden drastic maneuvers to avoid a collision, wind shear, catastrophic engine failure (blown jug, separated prop), and so on.

To be fair, Brian Denk, an RV-8 driver, wasn't intending to question the gear, but he did intend to conclude that we may never know, thus opening the door for the anecdotal conclusion that increased in volume with each accident.

But if the date sounds familiar to Van's historians, it's because of this: 1998 was the first year that Van's rolled out a tricycle gear kit. And it wasn't long before the first service bulletin was released. SB-98-10-1 called for a replacement of the nose gear leg on the RV-6A. Confusing the discussion a bit, the service bulletin didn't say why.

It would be a few years later, December 2000, that RV-9A owners were sent letters suggesting a check of gear legs, but this did not appear to be related to the design.

That didn't stop the online chatter, although it always surprised me that with the accumulated wisdom and expertise in the RV community (surely just about every occupation is represented), nobody ever put the design to an engineering test.

Van's points out, accurately, that they have. However in response to a growing number of online postings in 2005, a letter was released from Van's on the issue.

Van's Aircraft's own operational experience, over time, with 6 different tricycle gear RVs and a cumulative 7000+ hours, has been positive. However, as the number of flying kit built tricycle gear RVs has increased, so has the number of accidents involving damage to the nose gear. Because of the broad range of use and abuse to which the fleet is subjected, we find it difficult to categorize accidents and establish a precise cause and effect relationship. But with over 17 years and literally hundreds of thousands of hours of customer use, the nose gear has proven safe and practical for the vast majority of users.

That said, we recognized from the beginning that it would be impossible to make the tricycle gear configuration completely foolproof. In studying the NTSB accident reports it was obvious that pilot proficiency was the most significant factor that could be addressed. This awareness precipitated our push for transition training many years ago and is still a primary focus for Van's in keeping all RV pilots safe. This training has clearly been successful in reducing accidents associated with all RV models and its importance cannot be overstressed.

Well, there, they said it: pilot proficiency. But at the same time, they announced they were supplying new lighter forks, that also increases the clearance between the nose strut angle and the ground. At the time Van's indicated they would do testing to see if there was any evidence to suggest the new gear would inhibit the likelihood of nose gear strut failure.

I contacted Van's by e-mail this week to see if there had been enough data to make a conclusion one way or the other, but have not received a reply as yet. Tom Green, the president of Van's sent a spreadsheet listing a comparison of RV accidents and other models.

He prefaced his numbers with this explanation of what Van's is going through in accumulating the data.

"Bob, a few new nose forks have been in service now for a time... but our ability to track their "success" is not very good. We don't get hours of service reports from our builders. All we can do is to keep an eye on the NTSB accident reports... much like you should do. So far, to our knowledge no one has had any "reported" incident with one of the new forks."

"The best I can do is to 'mine' the NTSB incidents and so I have taken a baseline of the data for the last 5 years (just prior to my best guess as to the first 'usage' of a new leg/fork combination). My thoughts are that as each year passes we can look at the NTSB accidents using the same parameters and determine if there is a change or, if there is a change, is it due to something mechanical or is it due to better pilotage."

"I have attached the baseline Excel file that I produced on 7/13/2006. (see below) The study covers a 5 1/2 year period. I used the 'query' section and the keywords: "gear collapse", "inverted", and "fatal". I did this for a variety of aircraft models, both fixed gear and retractable, taildragger and trigear. I specifically did not include other homebuilts because homebuilts in general don't need to meet any standards of manufacture. In other words, I am holding Van's Aircraft kits to the standards of certified planes."

"My thoughts are that after one year, I will produce this search again and see if the numbers/percentages change. It is the only tool available to us that might be reliable and unbiased."

"As you can see if you look at the data, the RV ("A" models) have landing accident rates with "gear collapse" similar to the "retractable" models of many aircraft, but lower "inverted" rates and one of the lowest "fatal" rates."
" Bob, anyone can do this study but you have to also accept its weaknesses... the method of using the "keywords" will miss some accidents and add some in that it shouldn't but "on average" it is as close as I could get to a non-biased method. Please be aware of this weakness."

"My feeling is that It will take 3-5 years to see any differences that might be significant enough to draw conclusions. I doubt that reproducing the study in less than 1 year increments would be any value, so the next check will not occur until 7/13/2007."

As far as I know this is the first comprehensive release of data on the subject. But , oddly enough, data isn't behind a lot of the opinions. Most "evidence" presented is anecdotal.

And so is the refutation.

"Noseroller pilots can get away with being sloppy - taildragger folks are more likely to get bit in the rear with the design of the taildragger, so if everyone that flies noseroller RVs landed with the skill and care that taildragger pilots haved to display, that would probably improve it, too. Is the design safe right now? It's not as dangerous as some folks would have you believe, I don't think. I certainly don't have any qualms about going anywhere in a -A model RV. I've flown off grass strips in them, and I'm perfectly willing to keep doing it whether or not an improvement in the design, pilot training," says RVator Garret Smith, who provides a fine synopsis of the nosegear "debate" appears on golfsierra.org. (link fixed 11/16/06)

No real smoking guns, I don't think. It needs further investigation, that's for sure. Probably the design can be improved, but doing that at the expense of speed probably isn't going to be really popular. Many folks would rather go fast and take the (marginally smaller) risk than go slow. Can the design be improved without sacrificing (much) speed? Probably. If an improvement comes out, I'll be enthusiastic to put it on N257S. Could this be improved by teaching folks to land better? Probably. Noseroller pilots can get away with being sloppy - taildragger folks are more likely to get bit in the rear with the design of the taildragger, so if everyone that flies noseroller RVs landed with the skill and care that taildragger pilots haved to display, that would probably improve it, too. Is the design safe right now? It's not as dangerous as some folks would have you believe, I don't think. I certainly don't have any qualms about going anywhere in a -A model RV. I've flown off grass strips in them, and I'm perfectly willing to keep doing it whether or not an improvement in the design, pilot training, etc etc."

So let's go back overseas... to the UK, where rvsqn has been tackling this head...err... nose on.

First, there's the discussion of the proper technique used by "the A team." But the most interesting discussion seemed to revolve around the peculiar nature of the UK market, a thread spurred by an incident at Sywell, involving RVator Eddie Yates.

It's entertaining reading -- and, yes, the UK folks can flame as well as anyone -- but it also injected some interesting new elements of the discussion, including modifications on Glasairs that may be applicable to RVs.

That brings us all up to speed on the great nosegear debate, until the next flip-over, of course.