Year long discussion of "Another nosegear failure" -09/19/2010

[Ron Lee]

RVbuilder, clearly there are RV pilots who operate safely out of non-paved surfaces. The question then is what is different between those who do operate with no problems and those who flip?

You may have diagnosed this incident perfectly. You may have hit upon a generic problem reference soft field technique.

Does Mike Seager operate an A model extensively out of a grass strip? If so, what is different between his situation and those who flip on grass/dirt?

 

[N941WR]

...STAY OFF OF GRASS/DIRT SURFACES!...

Ummm, the the two A's I mentioned earlier were both on pavement. I'm not sure this is the answer.

...I too, may have landed a bit fast, and didn't flare properly...

Interesting point Larry. I wonder if the accident sequence starts with "fast" approaches.

Today I was helping a friend who is transitioning to his recently purchased -9A. The prior RV pilot he flew with was telling him to approach at 80 MPH / 70 Kts rather than the 70 MPH / 60 KTS dual or 65 MPH / 55 KTS Solo that I found works very well in the 9?s.

 

[rvbuilder2002]

Does Mike Seager operate an A model extensively out of a grass strip? If so, what is different between his situation and those who flip on grass/dirt?

Mike's base of operations is K05S (Vernonia Oregon). It is a grass runway. I believe he does most training operations from other airports and then when the students skills have been polished to the point Mike desires, they do landings at Vernonia.

I don't know the answer to the second question. Mike hangs out here on VAF some, maybe he is willing to comment.


I am thinking I didn't make my intended point very clear in my long post. The main point I wanted to make is that the situation has evolved to the point where if this type of accident happens, people seem to automatically assume it is totally the airplanes fault. My opinion is that a large % of the accidents were caused by mistakes that would have damaged most any airplane.

 

[L.Adamson]

Interesting point Larry. I wonder if the accident sequence starts with "fast" approaches.

Today I was helping a friend who is transitioning to his recently purchased -9A. The prior RV pilot he flew with was telling him to approach at 80 MPH / 70 Kts rather than the 70 MPH / 60 KTS dual or 65 MPH / 55 KTS Solo that I found works very well in the 9?s.

At least it was a "skip" bounce, and not a "plop" bounce, as in a stall. If I knew exactly what I did, then there wouldn't have been a problem, I suppose. There just must have been a moment of less attention. Because of full flaps, the nose may have also been pitched more downward.

My 6A speeds were the same as a Piper Archer. 90/80/70 knts. A friend fly's his 9A the same, except in mph, which is about 10 mph slower. I'd usually round out, looking to be close to the runway at 65 knts. From there, the speed diminishes very quickly, if power is at idle.

L.Adamson

 

[N941WR]

... A friend fly's his 9A the same, except in mph, which is about 10 mph slower. I'd usually round out, looking to be close to the runway at 65 knts. From there, the speed diminishes very quickly, if power is at idle.

L.Adamson

Still way too fast in a -9(A). Seriously, I do all my approaches with power off and 60 Kts with two up or 55 Kts solo and never drop it on. In fact, I can and do roll it on and used those same speeds with my friend's -9A. He was stunned at how smooth we were landing. BTW, both of those RV's have FP props. A CS prop might act differently due to the breaking effect and weight on the nose.

But this is a discussion for a different thread. maybe one we can hound each other about CS vs. FP props or ...

 

[L.Adamson]

Still way too fast in a -9(A). Seriously, I do all my approaches with power off and 60 Kts with two up or 55 Kts solo and never drop it on. In fact, I can and do roll it on and used those same speeds with my friend's -9A. He was stunned at how smooth we were landing. BTW, both of those RV's have FP props. A CS prop might act differently due to the breaking effect and weight on the nose.

But this is a discussion for a different thread. maybe one we can hound each other about CS vs. FP props or ...

His is also a Hartzell C/S. And just like my 6A, it doesn't "float" either. His 9A's speed also diminishes very quickly. We've both "plopped" it in, when experimenting.

edit: and as I remember, his 9A is at least 75-100 lbs. lighter.

 

[Ron Lee]

Like Tony, I know of a local -6A and a -9A that were both damaged (bent nose gear, prop strike, etc.) but did not go over. Those two will never show up on the stat's.

Ummm, the the two A's I mentioned earlier were both on pavement. I'm not sure this is the answer.

Yes and the one incident that I saw (after the fact) was due to pilot error landing on the nose gear. How about the two cases you mentioned?

A faster approach speed is NOT the issue in and of itself.

 

[L.Adamson]

But this is a discussion for a different thread. maybe one we can hound each other about CS vs. FP props or ...

Should my plane ever be rebuilt............we can argue as to whether I can land it, as a "6" or not. Or will I just groundloop it?

 

[Finley Atherton]

Still way too fast in a -9(A). Seriously, I do all my approaches with power off and 60 Kts with two up or 55 Kts solo and never drop it on. In fact, I can and do roll it on and used those same speeds with my friend's -9A. He was stunned at how smooth we were landing. BTW, both of those RV's have FP props. A CS prop might act differently due to the breaking effect and weight on the nose.

I use the exact same speeds with a CS prop. Any faster and my 9A can float excessively.

I agree with RVbuilder about landing technique (Post #302) but my understanding is that many of these incidents occur at slower speeds nearer the end of the landing when the nose wheel has dropped to the ground even with full back stick held. At this point it does not matter how good the earlier approach and touchdown was as the only option left is full back stick. In this phase of the landing all you can do is hold back stick and trust that you do not hit a bump big enough to contact the lower nose cone/bottom of the fork/big nut.

To take an extreme example it is even possible to have the strut fold back while parking if the lower nose cone fairing contacts the ground (note that this happened some time ago and with the older style fork/strut which had 1" less ground clearance that the current version).

This is why it is my strong belief that you must do everything possible to avoid nose cone contact including higher tyre pressure and maximising ground clearance under the lower nose cone fairing.

Fin
9A

 

[jjconstant]

I feel compelled to point out that there is actually a rather surprising variation in IAS from plane to plane, depending on airspeed calibration, or lack thereof. Maybe those people giving airspeeds that they use for approaches could include the IAS of their stalls so that someone with an indicated airspeed that reads faster than actual doesn't come in with too little energy. I think typical approach speed is 1.3Vso FOR YOUR airplane's indicated stall speed. I also think the mention of differences between CS and fixed was a helpful reminder as well as the differences between airframes (9 vs 6,7,8).

I fly a 7A, WW (light) CS prop. I can't remember my static weight on the nose wheel at gross off hand but it would probably be helpful to be included in these discussions too. In my airspeed calibration the gross weight stall occurrs at 57kts indicated. I use 1.3Vso=75kts on approach (actually should be 74 but I'm not that good yet). I'll keep it there until I need to round out. I also have AOA and 75kts lights up the first amber LED at a normal glide slope with a bit of power. This feels rock steady. If I come in any slower things can easily get very wobbly and I instinctively add power. I just don't like it when my RV starts wallowing like the Cessna 150 I trained in Yeah, I could probably come in a hair slower, but why? I still can easily make the first turnoff at 1500ft when I want, but I am perfectly comfortable not using the brakes at all and letting it roll to the next one at 2000ft. There's another 3000 to play with. I have 210hrs and I'm still on the set of brakes and tires that came with the kit. I am always quick to add power in the flare if there's even a sniff of anything not right. The amount of power added is directly proportional to the size of the question mark hovering over my head during flare

Just blindly using someone else's numbers could be very painful. Especially if it's a different model or the same one with very different equipment, calibrations and W&B.

 

[rocketbob]

"Fortunately the anti-splat mod does the trick. If you don't have the anti-splat mod, you're crazy!!"

I must be crazy or I missed something? Where is the proof? Real world testing? Statistics? Show me the proof and I'm in. Allan has a very nice video on his site, but that isn't the proof it will prevent this from happening.

I transitioned trained with Mike Seager up in Oregon on a grass strip. Average condition for a grass strip. "A" models fly out of there all the time. No "A" model flip overs to my knowledge on this grass strip.

Every morning I look at the latest NTSB accident reports. What I find interesting is that a good percentage of accidents are nose gear collapses on many GA airplanes. An interesting statistic. Is it poor flying skills? Bad hardware? I don't know but maybe there is something in these statistics that is telling us something.

I agree with Allan that with the existing nose wheel bearing/fork design you can pinch the bearing and cause additional drag on the wheel. However a simple machined spacer inserted between the two factory spacers solves that problem.

So no reports of flip-overs with Allan's mods isn't good enough for you? I suggest if the practicality of his simple and inexpensive mods doesn't work for you, take your chances.

Like I said I know of SEVEN, repeat SEVEN RV nose gear failures near me and if RV's were somehow comparatively within the fleet percentages of nosegear failures of other airplanes then there would be piles of wrecked C150's 172's, Cherokees, etc around here.

 

[Ron Lee]

Like I said I know of SEVEN, repeat SEVEN RV nose gear failures near me....

Bob, that is interesting yet of no value in objectively looking at this issue WITHOUT facts surrounding each event.

I know of one event and it was clearly pilot error based upon the eyewitness reports.

My suggestion remains: Stay off of grass/dirt runways and we can add to that "Do not land on the nosegear."

I also know of one RV-6A landing on a paved runway where the nose wheel fairing was torn off. Factors: The runway had large cracks in it. They landed with a non-trivial tailwind. So paved runways in poor condition should also be avoided.

Oh my...Three operational restrictions that should make this a non-issue. I can live with those.

 

[Ironflight]

Like I said I know of SEVEN, repeat SEVEN RV nose gear failures near me and if RV's were somehow comparatively within the fleet percentages of nosegear failures of other airplanes then there would be piles of wrecked C150's 172's, Cherokees, etc around here.

Actually Bob, if you read the daily FAA accident reports, you'd find that there are WAY more reports of wrecked landing gear on Cessnas, Pipers, etc in a month than RV's. Of coure, the Certified fleet is larger, and the only accidents listed are those that are reported - many aren't.

 

[Ron Lee]

There is useful info on at least one of the SEVEN flips that Bob knows about locally. From Post #11:

He used to keep his airplane in my hangar but was concerned about the nosegear not being up to the rough spots in the runway, so he moved it to a nearby airport. Yesterday he elected to not give rides to friends until the wind shifted in favor for 18 which is smoother. This was his third landing of the day here.

Had the nosewheel fork mod according to Van's service bulletin.

Landed and rolled out over a spot on the runway with a bit of a hump. Following the hump is a low spot where grass does not grow well. The airplane took a bounce over the hump and the nosewheel came down in the bare spot. It was clear to see where the front wheelpant broke and the nut started digging in.......

So the runway had conditions that are not suitable for an A model. The pilot knew about it but made multiple landings/take-offs anyway.

Then Bob knows of a pilot who has flipped TWICE. Come on folks. You want to use that as justification that the nose gear is a horrible design that is just waiting to nail you?

Judgment folks....judgment.

Stay off of poor paved runways and unimproved runways.

There is a grass strip west of here that a Cub pilot with tundra tires claims is like a putting green. It sounds like a nice area but without firsthand knowledge of the conditions, I will not land there. I probably would not even if I knew that it were perfect.

I am looking at the wheel bearing mod. Maybe I will do it...maybe not.

 

[Av8torTom]

Can't Hurt

I'm in the nose job modification can't hurt camp. I am not convinced either way about its effectiveness, but I am convinced that it won't hurt anything either.

For those of you who are waiting for poof of it's effectiveness, forget it - you're going to wait a LONG time because you're trying to prove a negative. Not impossible, but you'll need a ton of data points.

We may be able to prove it DOESN'T work if we look at the data 10 years from now and can show there is no difference in the number of flip over events between those A models with and those without the modification. Again though, a lot of data will be needed.

So unless someone can convince me that there's an inherent risk to doing the modification, I plan on putting one on my 9A along with the wheel bearing change.

 

[868RM]

restrictions

Ron, I could not accept 2 of your 3 operating restrictions. We cannot make new nose gear parts to fix all pilot errors. However that is what I love about experimental aircraft , we can cover the minor ones. In my case Ron's restrictions are just unacceptable so I made the changes I felt were needed to still be safe on grass with a nose wheel. I feel the brg. spacer with std. wheel is must on any surface. The spacer "stiffens" the fork to keep the bearings from skewing and binding. Next it is much more difficult to skew and bind a ball bearing, hence brg. change. The anti-splat strut is such a simple add on I don't understand the reluctance to put one on. If lots of grass strips is your normal (I fit in this group) the 5.00x5 nose wheel and g380-150-5 main tires roll over bumps with a lot less effort. The nose gear is more likely to flex up instead of back.This requires a new fork. A complete new nose gear can be made too. They are not that expensive and are made by the same shop that made the nose leg that you have now. None of these options are very difficult and WILL help prevent flip overs. Physics works with or without statistics. Ron

 

[Ron Lee]

Ron, you need not heed my operational restrictions. You have made the mods that you feel are needed. There are folks who successfully operate out of unimproved strips.

But my view...without hard data...is that the majority of the flips are on unimproved surfaces. It may also be by pilots with limited experience on those surfaces.

So the OBVIOUS solution is stay off of unimproved surfaces if you are not 100% certain that you can successfully use it. The initial post was because a pilot who had left an airport with an unimproved strip made multiple landings/take-offs. Until the flip occurred. It should never have happened.

My flying is not substantially impacted by avoiding unimproved surfaces.

Make the mods or not. But these incidents can be reduced to near zero (opinion) if RV-xA pilots stay off of unimproved surfaces (qualified folks exempted).

 

[868RM]

Ron, Very well stated. I hope that "A" pilots do their own research and determine that there are a few simple things that will help. Ron

 

[rvbuilder2002]

I agree with RVbuilder about landing technique (Post #302) but my understanding is that many of these incidents occur at slower speeds nearer the end of the landing when the nose wheel has dropped to the ground even with full back stick held.

I don't pretend to know all the answers, but I can imagine a possible cause for this....

A large # of the flip-over accidents that I have first hand info. about were situations were the pilot was getting short on runway remaining. Some of these were situations where the pilot was still in the air and forced the airplane on the ground (pretty much guaranteed to ruin your day). Many of the others were good landings (they resisted forcing the airplane on the ground and waited to touch down in a full nose up flair), but because of extra speed and/or miss judgment of a proper touch down point they ended up rolling a bit long on the runway and the flip happened near the end of the roll-out.
Think for a minute about the dynamics of this situation...
Airplane is still rolling moderately fast so the pilot is braking hard. Because of the vertical position of the C.G. relative to the main and nose wheels, this automatically shifts more weight than normal, onto the nose gear. If the pilot is holding full back stick (as he should be), this will help counter the pitching moment produced by the de-acceleration. But what if the situation is getting a bit tight and the pilot keeps the hard braking going right until the end. So there is a strong pitching moment throughout the entire roll-out, but as the speed is decreasing, the elevator authority is decreasing. This means that the weight load on the nose gear may be increasing during the entire roll-out.
An example of this we have all experienced is an emergency stop in a car. The front end dives towards the ground and we are pushed fwd against the belts. If it is a true panic stop in a vehicle with ABS, we will stay tight against the belts until the instant that the vehicle actually stops.
The exact same thing happens in the airplane. The pitching may actually be worse because of how tall the airplane sits up on the gear.
We have something the car doesn't have.... pitch control. This helps reduce the pitching moment... until its effectiveness is reduced because of low airspeed. Add into the situation a bad pump just before the airplane is about to stop (now very low elevator effectiveness, but highest amount of weight on the nose gear), which pitches the nose up and it slams back down with the original increased load caused by the hard stop + the acceleration added from the nose dropping, and we have a bad situation.
So you might say that not all of the accidents happen near the end of a runway. I agree.
What if, because it is a shorter grass runway (a lot of them are) a pilot decides to practice his short field landing skills (or maybe a bunch of his buddy's are watching) so he brakes hard even though he didn't really need to. (Refer to explanation above of what can happen if you brake hard to a complete stop). He is actually trying to see how short he can land (or impress his buddys), so he is going to brake hard to a full stop right? He is not going to think, there, I got it slowed down to 30 kts pretty quick, and then stop braking.
Now he may have done everything right (right on the proper airspeed, and touched down at the very beginning of the runway), so that he will be stopped at about the mid point of a 2000 ft runway (actually pretty good performance for someone that doesn't do it all the time), but he didn't need too, and he may pay a hard price for it.

I can imagine scenarios (but still guesses, just like everyone else) that could explain many of the flip-over accidents. The explanation above I believe covers a lot of them, particularly if you also add in improper maint. (low nose tire pressure), excessive weight on nose gear, etc., to the mix. One thing I am sure of... we don't always hear all of the pertinent details of these accidents. I don't mean to imply that it is always intentional (though I think it sometimes is), but if we did know all the facts, I think most of us would have a very different opinion about what caused the accident.

 

[tjo]

Keep in mind that I am not an RV pilot yet. I am building a 9 and I am in the process of convincing my wife that this is the right choice over a 9A. I started in a Cub, she didn't.

That said, I have seen quite a few RV's land and have been surprised at how many A models I have seen touch down on the nose gear at almost the same time as the mains. I am assuming that the pilots are thinking that they are high on the mains, but they aren't. Incidentally I have seen the same behavior with certified airplanes as well.

I have also found it interesting that I did my primary training on airstrips that were mostly 3,000 feet or less, and a good third of my landings were on short grass strips. I can tell you that people who "grew up" on 5,000 foot paved strips will think they are runnng out of runway, when in reality there is lots of room left. I can also tell you that landing on 1,000 feet of grass with even just tall grass at the end looks awfully short and intimidating and could cause someone to unnecessarily use the brakes, but if done properly, you stop well short of the end of he runway, at least in a Cub.

I have no idea if this is a cause, but it may be a contributor. I am not a high time pilot, but I try to be as observant as possible and I try to push myself to continually learn.

Tim

 

[Ron Lee]

Tim, I have recently seen USAFA pilots wheelbarrow/porpoise in expensive Cirrus aircraft at my airport. I do not know if students were at the controls or rated pilots, still, poor technique.

 

[Finley Atherton]

I agree with rvbuilder's analysis of how heavy braking towards the end of the landing roll puts a greater load on the nose wheel.
Most of my landings are on my short grass strip and I try to brake heavily as soon as the mains are on the ground with increasing back stick to hold the nose up and then easing off the brakes as the nose comes down so hopefully there will be little need for braking towards the end on the landing roll.

However there has been many occasions where I have had to use at least moderate braking after the nose has come down including on some very rough grass strips. I believe that the strut will take a lot of punishment and will naturally want to flex fwd and up out of danger even under heavy braking on a rough surface provided there is no excessive drag that could force the strut to move back and down instead. That excessive drag could be caused by tight or binding bearings or the lower nose cone contacting the ground. Hence my obsession that everything be done to help prevent the nose cone grounding including high tyre pressure and rasing the lower surface of the nose cone fairing to give more clearance.

Greater clearance does allow the nose wheel to hit a higher bump without grounding but the impact point will be more fwd and higher up on the tire as shown in the Antisplat video and maybe this is when the antisplat brace could be a good backup???

Fin
9A

 

[PerfTech]

A Little Added Safety No Harm No Foul!!!!!

...It seems that most of the discussion on this thread has been hashed over many times here on this forum. I am quite sure most people are aware of the dynamics at work when braking heavily and the need to avoid as many holes and depressions in the ground as possible. The items from ASA offer some added safety when needed and we have demonstrated this in the video and with a multitude of other tests not in our video. Many factors contribute to this issue, poor technique, surface, wheel drag, lack of experience, mechanical failures, a forced landing and many more. The bottom line is the products offer some added safety, and if available at a reasonable price, one should take advantage of the opportunity at hand. To make a statement like its all technique, or I don't make mistakes, so you don't need it is bordering on irresponsible. With that line of reasoning one could suggest removing the roll bar, seat belts and shoulder harnesses. After all, they just add weight and in a perfect world they definitely aren't needed. I have had several off field forced landings in my forty plus years as a pilot and I can say with 100% certainty that when it gets real quiet up front or the smoke is coming out so goes a lot of technique. That is when the if only I Coulda, if only I Woulda, I Shoulda, begins and that is sad. Also it seems possible Vans made a blunder in putting that more expensive, much larger, stronger, more complex and somewhat better designed nose gear on their new RV-14. Why not keep the original design, beefed up if needed? If it wasn't broke, why fix it? My Three Cents, Allan

 

[tjo]

Allen, I think you have a good product and I am impressed with the professional development that you have put into it as well as the transparency with which you have provided data. It is to be applauded. If I do build an A, I very likely will put your stuff on it.

That said, the guys at Vans are also very experienced not only as pilots, but with their machines as well, and they choose to fly without them. I don't consider them irresponsible, or I wouldn't be buying stuff from them.

There have been many times during my career that I have dealt with experts with differing opinions. I have also BEEN an expert with a differing opinion. It will happen as long as we can't prove something for sure.

Tim

 

[PerfTech]

Allen, I think you have a good product and I am impressed with the professional development that you have put into it as well as the transparency with which you have provided data. It is to be applauded. If I do build an A, I very likely will put your stuff on it.

That said, the guys at Vans are also very experienced not only as pilots, but with their machines as well, and they choose to fly without them. I don't consider them irresponsible, or I wouldn't be buying stuff from them.

There have been many times during my career that I have dealt with experts with differing opinions. I have also BEEN an expert with a differing opinion. It will happen as long as we can't prove something for sure.

Tim

...Thank you for pointing out that I may have worded my previous post in such a way that it's meaning could be misconstrued. I don't consider them irresponsible at all and didn't mean to come across that way. I have the utmost respect for all of them and their company as well. I believe collectively they have done more to further general aviation than anybody. I was simply trying to say many people out there don't posses the skills or have the same experience and this add-on may help save a few of them a lot of grief. I have never flipped an aircraft (knock on grass) in over 14K landings but in looking back, some of those would have definitely bent the nose gear were I in my RV-9A. This being said I was a little nervous about this issue and decided to address it. Over the years many wonderful automobiles have been designed and produced. Then came seat belts and the safety improved. Then all could be bettered with airbags, I look at this the same and hope I don't have occasion to test them. I think they (Vans) have a wonderful product and have tried to address most every issue that came about. I also see they have addressed this issue on the new RV-14A. That doesn't suggest or imply they dropped the ball on the other A models. It just shows they are on top of and improving their products. Again, apologies if I offended anyone as I didn't intend it. Thanks, Allan...

 

[rvbuilder2002]

...It seems that most of the discussion on this thread has been hashed over many times here on this forum. I am quite sure most people are aware of the dynamics at work when braking heavily and the need to avoid as many holes and depressions in the ground as possible.

...Thank you for pointing out that I may have worded my previous post in such a way that it's meaning could be misconstrued.

I don't think anyone misconstrued your first post... I think it is pretty clear what you meant to say

Just to be clear... the post I made explaining my opinion on how a flip over accident could possibly happen at slow speed near the end of a landing roll out was in response to someone asking the question. So it may all seem clear to some people, but obviously not to everyone.

To make a statement like its all technique, or I don't make mistakes, so you don't need it is bordering on irresponsible.

I agree, so I hope this wasn't addressing me, because I never said any of those things.
In the same vein, I think it is irresponsible to imply even the hint that if someone doesn't choose to buy your products, that they are foolish and irresponsible (I am not say you have Allen, but other people surely have).

- - - - - - - - - - - - - - - -

My only motivation for even getting involved in this thread was to get people to look at it with eyes wide open, and maybe consider that many of the accidents are the blame of the pilot and that the outcome may have been exactly the same regardless of what airplane they were flying. If nothing else, I am hopefully encouraging people to do a serious self evaluation of their own personal flying skills. There comes a point when no bolt on fix will save someone from some of the situations people get themselves into. I still firmly believe that is the scenario for a lot of the flip-over accidents.

There is nothing at all wrong with people choosing to add Alan's product to their airplane. My biggest fear though, is that a lot of people are doings so, and now flying with their guard down. They might be thinking that they no longer have to worry, when what they should really be worried about is their less than stellar performance as a pilot. Sorry, I know that can sting a bit, but the best thing we all can do is put our selves in a position were our friends feel empowered to tell us things we need to hear. Even better, is to seek out a good RV pilot and ask them to fly with us ans really critically critique what they see. I know we all do flight reviews every other year, but a lot of those really don't happen in the context that I am describing.
Something good for all of us to consider....

 

[nineninefour]

I started my professional life as a safety engineer, doing system safety work on the space shuttle main engine testing program. I am currently a structural engineer (following a masters degrees and some years experience).

In the safety business, our rule was that although we could use human element programs (training, procedures) to prevent mishaps, we were to engineer out things when we could. This issue sounds like one of these. While excellent pilot technique might be a fair control, if we can actually determine the necessary design and construction feature changes, we should strive for those. The other part is that in the event of an unexpectedly rough field, or in an emergency landing situation, we should probably expect the nose gear to remain useable.

The thing that could cause FAA intervention is lack of recognition and responsiveness among amateur builders, when problems are not fixed. We do not want that, so we should not simply blame the pilot and bury our heads in the sand.

 

[ColoRv]

...Thank you for pointing out that I may have worded my previous post in such a way that it's meaning could be misconstrued. I don't consider them irresponsible at all and didn't mean to come across that way. I have the utmost respect for all of them and their company as well. I believe collectively they have done more to further general aviation than anybody. I was simply trying to say many people out there don't posses the skills or have the same experience and this add-on may help save a few of them a lot of grief. I have never flipped an aircraft (knock on grass) in over 14K landings but in looking back, some of those would have definitely bent the nose gear were I in my RV-9A. This being said I was a little nervous about this issue and decided to address it. Over the years many wonderful automobiles have been designed and produced. Then came seat belts and the safety improved. Then all could be bettered with airbags, I look at this the same and hope I don't have occasion to test them. I think they (Vans) have a wonderful product and have tried to address most every issue that came about. I also see they have addressed this issue on the new RV-14A. That doesn't suggest or imply they dropped the ball on the other A models. It just shows they are on top of and improving their products. Again, apologies if I offended anyone as I didn't intend it. Thanks, Allan...

You say you're not suggesting Van's dropped the ball on the A models, and yet it seems that you suggest exactly that in nearly every post. There appears to be quite a bit of scare tactics in your sales approach and insinuating that anyone who isn't writing you a check is reckless.

The bottom line is the products offer some added safety, and if available at a reasonable price, one should take advantage of the opportunity at hand. To make a statement like its all technique, or I don't make mistakes, so you don't need it is bordering on irresponsible.

It's irresponsible to trust Van's engineering over yours? What are your credentials for saying such a thing? A good product doesn't need these tactics to sell. Van has proven himself and his company many times over.

If you have the standard Vans front wheel bearings and outside spacers then you are on the ragged edge any time you encounter an irregular landing surface.

Snakeoil. Your previous post was misconstrued? Many of your posts seem to say something along these lines. It's a free country and you have the right to slander whomever you please unless they decide to stop you. But slandering Van to make a buck is just a bit off I think. Perhaps your products do add a slight measure of safety, or perhaps they don't....nothing has been proven. It's all stories of unreported blah blah blah and promises of cure all doodads. I've seen my share of accidents, and was jump master in a cessna where the PIC ripped the gear and wings off at the end of the runway...and one thing I'm fairly certain of is the percentage of pilots that admit they porked the pooch after they've clearly and unmistakably done so...is pretty low. Some of the stories of flips are questionable at best, some are quite certainly pilot error that couldn't have been prevented with carrier gear on the front...and maybe some are due to the gear being too weak...for the load the builder/pilot put on them. Bigger engines, constant speed, desire for more baggage capability moving CG further and further forward....I think there is possibly enough blame to go around. I'm very confident of one thing though....if Van thought there was a real issue...he would have said so. Sure, he changed the gear on the bigger, heavier airplanes with six cylinders hanging off the front..and you're trying to turn that into an implied design fault on the smaller, lighter, 4 cylinder planes? Seriously?

 

[Captain Avgas]

My only motivation for even getting involved in this thread was to get people to look at it with eyes wide open, and maybe consider that many of the accidents are the blame of the pilot and that the outcome may have been exactly the same regardless of what airplane they were flying. If nothing else, I am hopefully encouraging people to do a serious self evaluation of their own personal flying skills.

Scott, I appreciate your comments, despite the fact that I have been a long term critic of the RV sprung steel nose gear dating back to 2005 when the issue of RV nose failures first began to gain real steam on VansAirforce.

I was taught during my initial training to keep the nosewheel off the ground on landing, and I thought that I did so in a reasonable manner. That was until I did RV transition training with Mike Seager in 2006. Then I promptly understood that my technique was totally insufficient, at least for RVs. He completely changed my perspective...and my technique.

The problem is that most RV pilots graduate from learning to fly on Cessnas and Pipers which obviously have much more forgiving nosegear designs. Typically they bore down the runway at take-off with the nosewheel firmly planted on the ground and pull back on the stick to rotate. On landing they plop the nosewheel down within seconds of the mains touching. You only need to go to any major GA airport to see that this is the norm for most private pilots.

The danger for many RV pilots is that they just don't realise how inadequate their technique really is for RVs. I flew as a passenger with an RV9A pilot recently and I asked him before we left if he made it a practice of keeping the nosewheel off the ground whenever he had elevator authority to do so. He said "yes, always", and then he promptly took-off flat and landed flat. He knew what he was supposed to do in theory....but in practice he just didn't do it.

So my recommendation for any RV pilot who wants to spend some money to improve safety is to start by spending it on some quality transition training with a reputable RV instructor. That could be a very beneficial and illuminating exercise.

I still believe that the RV sprung steel nose gear is fragile, but I draw considerable comfort from the fact that Mike Seager, who reportedly has +12,000 flying hours in RVs (most of them instructing low time pilots), doesn't appear to have collapsed an RV nose gear yet. This is despite the fact that he routinely takes students in and out of Vernonia which is a pretty ordinary turf strip surrounded by high trees. I think that probably says volumes about the advantages of good technique.

 

[woodmanrog]

OK, I'm going to chime in

I have avoided this forum for a long time but after reading some of these comments, I thought I would enter some of my real world experience. There is always room for improvement on any product be it car, airplane or whatever. That being said: I resisted putting any stiffener on my nosegear airplanes (2 RV6's) because Van's says they are not necessary. I have repeatedly told prospective customers that a nosegear stiffener wasn't necessary to purchase. Well, I have changed my mind. After viewing my friend RV6airplanepilot's videos, I was convinced that I had to at least give it a try and see if there was any difference on my own plane. I installed one of the stiffeners that I personally make, albeit with some minor modifications, and am now convinced that there is really a marked improvement as to vibration and flexation. I am going to purchase the Lipskid device from Allen because it seems to make practical sense and is a relatively inexpensive and simple mod. So my final assessment is that there is improvement in stiffeneing up the standard nosegear no matter which route you want to persue, Perftec or homemade. You will feel a difference, gauranteed.

 

[David-aviator]

Well, I have changed my mind. After viewing my friend RV6airplanepilot's videos, I was convinced that I had to at least give it a try and see if there was any difference on my own plane.

No question, your device will stiffen the NG strut. But if that video is the same one I viewed a while back, it is not a totally valid reason to conclude the stiffener is necessary. The video I saw obviously was the result of "holding" the NG on the surface way beyond take off speed. My technique with the 7A was to start the take off roll with some back pressure just like when taxiing and keep the NG unloaded. That technique works both on take off and landing and did so for 5 years of grass ops before we black topped our runway and with a very heavy Subby engine up front.

And this is from a perspective of having experience a flip with that same airplane when the Subby quit one day and the landing was on soft river bottom sand not far from the Missouri River. I do not believe the stiffener would have mattered. The NG bent back when it dug in that was it even aft coming to an almost complete stop.

Keep the weight off the NG as much as possible during take off and landing and barring very bad surface, you will be OK. Also, keep in mind the NG is not designed to be landed on any more than it is on a jet airliner. It is for slow speed and taxi only.

 

[badmrb]

Are we still talking about the antisplat brace?

If we are still talking about the anti splat brace, its not a stiffner. The point is to not affect the nose gear or its movement under normal conditions. It only comes in contact when the gear is rolling back under because of a severe enough stress to cause gear failure. When it works, things ARE gonna get bent, but higher up at the attach point.

The wheel bearing mod helps stop the situation where the stock bearing is locking/ unlocking and causes the gear to start that forward/back motion.

If we arent talking about the antisplat device then i guess its a whole different discussion of what happens when the nose gear is made rigid and what that does.

 

[L.Adamson]

If we are still talking about the anti splat brace, its not a stiffner. The point is to not affect the nose gear or its movement under normal conditions. It only comes in contact when the gear is rolling back under because of a severe enough stress to cause gear failure. When it works, things ARE gonna get bent, but higher up at the attach point.

The wheel bearing mod helps stop the situation where the stock bearing is locking/ unlocking and causes the gear to start that forward/back motion.

If we arent talking about the antisplat device then i guess its a whole different discussion of what happens when the nose gear is made rigid and what that does.

I do believe we're now talking about wooden type stiffeners, as well as the anti-splat. Note: In the old 6A day's, it was common to wrap a wooden stiffener with fiberglass for the nose gear leg. The fiberglass was the actual finished portion of the leg. No pre-made fairings back then.

 

[az_gila]

.....

The wheel bearing mod helps stop the situation where the stock bearing is locking/ unlocking and causes the gear to start that forward/back motion.

.....

Interestingly the RVbuilder2002 long response does not mention the front wheel motion.

http://www.vansairforce.com/community/showpost.php?p=701356&postcount=321

It's quite visible to onlookers but not even felt by the pilot. I can't believe that an oscillation like this doesn't have some resonance point....

 

[PerfTech]

...Scott, It seems I owe you an apology and need to clear up a few things. I wasn't addressing you in that post at all, but rather the whole thread as many of these things have been said before. I think your post was great and agree with you on every statement. I have said most all of them myself. I am perhaps a little too passionate about this product and sometimes jump to it's defense to soon becoming frustrated when people don't understand what I was trying to convey. Again I apologize and want you to know this frustration wasn't aimed at you. Thanks, Allan

 

[RetiredRacer]

I would never have thought you could

I agree with rvbuilder's analysis of how heavy braking towards the end of the landing roll puts a greater load on the nose wheel.
Most of my landings are on my short grass strip and I try to brake heavily as soon as the mains are on the ground with increasing back stick to hold the nose up and then easing off the brakes as the nose comes down so hopefully there will be little need for braking towards the end on the landing roll.

However there has been many occasions where I have had to use at least moderate braking after the nose has come down including on some very rough grass strips. I believe that the strut will take a lot of punishment and will naturally want to flex fwd and up out of danger even under heavy braking on a rough surface provided there is no excessive drag that could force the strut to move back and down instead. That excessive drag could be caused by tight or binding bearings or the lower nose cone contacting the ground. Hence my obsession that everything be done to help prevent the nose cone grounding including high tyre pressure and rasing the lower surface of the nose cone fairing to give more clearance.

Greater clearance does allow the nose wheel to hit a higher bump without grounding but the impact point will be more fwd and higher up on the tire as shown in the Antisplat video and maybe this is when the antisplat brace could be a good backup???

Fin
9A

....brake while holding the nose up. I thought this would slam the front wheel down. I don't know about yours Fin but with a fair amount of fuel on board and with no passenger or luggage I have trouble holding the front off. But when we are traveling with luggage etc, if we have a distance to travel to clear the runway I'll keep the idle up a little and taxi with the front held up. But if you check the trim tab there is very little difference between loaded and empty.

 

[Finley Atherton]

....brake while holding the nose up. I thought this would slam the front wheel down.

Yes, can be done in my 9A at least - don't know about other RV models with smaller elevators and I am just a lowly private pilot and have no special authority/experience to suggest others do the same!

This technique works best for me on a short field landing where there is no extended flare as I want to get on the ground quickly. The extra speed at touch down means there is enough power in the elevator to keep the nose up with brakes applied for a short while. Its a sort of a balancing act between the brakes and increasing back stick. Raising the flaps immediately after touch down can also help keep the nose up slightly longer. Obviously I let the brakes off just before the nose wants to drop to prevent it slamming down hard.

I find the technique does not work as well on a long runway because I think I must automatically extend the flare and the slower touch down speed means the nose wants to drop sooner.

Let me know if you ever plan to fly into Armidale.

Fin
9A

 

[nineninefour]

Has anyone here instrumented a nose gear (i.e., strain gauges along the forward and aft gear surfaces) to looking at loading, load rates, deflections, etc.? We could fairly easily do this, accumulate some data, and come to some conclusions about bending forces with various mods and under various operating conditions.
Modeling is good, but I suspect we don't know enough yet about the loads and forces involved at various phases of landing and on various surfaces to construct an accurate model.

 

[RetiredRacer]

I believe that the strut will take a lot of punishment and will naturally want to flex fwd and up out of danger even under heavy braking on a rough surface provided there is no excessive drag that could force the strut to move back and down instead. That excessive drag could be caused by tight or binding bearings or the lower nose cone contacting the ground. Hence my obsession that everything be done to help prevent the nose cone grounding including high tyre pressure and rasing the lower surface of the nose cone fairing to give more clearance.

Greater clearance does allow the nose wheel to hit a higher bump without grounding but the impact point will be more fwd and higher up on the tire as shown in the Antisplat video and maybe this is when the antisplat brace could be a good backup??? [End Quote]

I agree with your thoughts here Fin but I hadn't thought of the nose cone drag before and as someone else mentioned, that the nose cone could be pushed back into the tyre compounding the issue.

Thanks for the invite, your only a couple of hrs. I'll email you.

 

[PerfTech]

I believe that the strut will take a lot of punishment and will naturally want to flex fwd and up out of danger even under heavy braking on a rough surface provided there is no excessive drag that could force the strut to move back and down instead. That excessive drag could be caused by tight or binding bearings or the lower nose cone contacting the ground. Hence my obsession that everything be done to help prevent the nose cone grounding including high tyre pressure and rasing the lower surface of the nose cone fairing to give more clearance.

Greater clearance does allow the nose wheel to hit a higher bump without grounding but the impact point will be more fwd and higher up on the tire as shown in the Antisplat video and maybe this is when the antisplat brace could be a good backup??? [End Quote]

I agree with your thoughts here Fin but I hadn't thought of the nose cone drag before and as someone else mentioned, that the nose cone could be pushed back into the tyre compounding the issue.

Thanks for the invite, your only a couple of hrs. I'll email you.

...I wanted to chime in here and let you guys know that the "Lip Skid" product does help stop the wheel pant from being pushes back into the tire. They fit very close to the nose of the wheel pant and will carry a tremendous load. This location only allows the wheel pant limited movement when stressed or is hit from the front or bottom. Please see video link below (view the seventh video). Thanks Allan...
http://antisplataero.com/Videos.html or see this You-Tube clip;
http://www.youtube.com/watch?v=De2Q3je7k3w

 

[rocketbob]

Then Bob knows of a pilot who has flipped TWICE. Come on folks. You want to use that as justification that the nose gear is a horrible design that is just waiting to nail you?

Absoultely. The nosegear should be structurally strong enough to withstand poor technique, within reason. I'll bet there has been millions of landings on our strip as it is busy with a flight school and a lot of those same Cessnas can tolerate poor piloting.

This thread and none of the conversation would be occurring if the gear were strong enough in the first place.

 

[MrNomad]

RV6A flying

Bob:

Once again, allow me to thank you for all of the assistance and guidance you provided during the rebuild of the O-360 we installed in the RV6A. It has 80 hours and continues to purr along thanks to the ideas and suggestions we got from you.

Barry

 

[Ron Lee]

This thread and none of the conversation would be occurring if the gear were strong enough in the first place.

Or people understood its limitations and avoided inappropriate landing surfaces.

One pilot with two flip-overs?

 

[sglynn]

Nose Gear Modifications Summary

So after reading this very long thread, and being in the middle of building my RV-7A nose gear I want to implement the best modifications to date.
Therefore, are these 4 plus 1 modifications the best things to do to the nose gear:
1) Nose Job from Antisplat
2) Tip Skid from Antisplat
3) Bearing modification from Antisplat
4) Matco axle mod
5) Practice super pilot technique. Land on the mains, keep weight off nose gear by keeping stick back, no hard breaking, watch for crummy runways, beware of grass runways.

Do these all go together? Is Matco axle compatible with Bearing mod from Antisplat?

thanks

 

[MauiLvrs]

Do these all go together? Is Matco axle compatible with Bearing mod from Antisplat?

Without 5 ... 1-4 may not mater.
With 5 ... 1-4 likely doesn't matter.

Read what Bob said.

Has anyone here instrumented a nose gear (i.e., strain gauges along the forward and aft gear surfaces) to looking at loading, load rates, deflections, etc.?

That sounds like actual engineering ... Think that Van's has done that...

The problem is that most RV pilots graduate from learning to fly on Cessnas and Pipers which obviously have much more forgiving nosegear designs.
...
So my recommendation for any RV pilot who wants to spend some money to improve safety is to start by spending it on some quality transition training with a reputable RV instructor. That could be a very beneficial and illuminating exercise.

What Bob says...

One could put a 152 nose gear on an RV and take away 60 HP to make up for the weight.

 

[paul mosher]

152 gear

The 152 gear may be stronger but Cessna bolts them to the firewall. Not unusual for them to come off when wheel barreled on landing. I bought a 182-A project that had the nose gear ripped off.

 

[zilik]

Therefore, are these 4 plus 1 modifications the best things to do to the nose gear:
1) Nose Job from Antisplat
2) Tip Skid from Antisplat
3) Bearing modification from Antisplat
4) Matco axle mod
5) Practice super pilot technique. Land on the mains, keep weight off nose gear by keeping stick back, no hard breaking, watch for crummy runways, beware of grass runways.

Do these all go together? Is Matco axle compatible with Bearing mod from Antisplat?

thanks

My $0.02 worth of advice. I assume you have the latest and greatest gear leg and fork from Vans.

All the Antisplat stuff can't hurt except in the weight department. Keeping the tire inflated to 50psi and treating the nose gear with respect will go a long way too. But you have to acknowledge that no matter how many mods, etc, nothing will save the gear if the hole is big enough.

 

[pa38112]

The anti-splat wheel/bearing modification and the Matco axel are two different approaches to the same issue - it is one or the other. Pick one.

 

[Dmadd]

I'm kinda late to this discussion, but I'm wondering if anyone in the "A" community has suggested retracting flaps as soon as your on the ground. It will give your elevator much more authority and you'll be able to fly the nose wheel to a much slower speed...
If I missed it somewhere in the nine pages before this post, I apologize...

Dennis

 

[flyboy1963]

accident data collection?

Dennis, hard to stay current on all 36 pages......
some have suggested we try to identify the 'smokin' gun' by collecting data, but it's not easy.
I just wanted to respond that 'many' of the nose collapses, or flips, apparently occur at much lower than landing speeds, so the focus on technique, while admirable, will not 'fix' the problem.
Aircraft TAXIING have flipped, at perhaps 10 mph, just enough energy to cause the tuck 'n roll .....it appears!
Experienced pilots with great technique have been bitten while taxiing across an uneven pavement seam. How do you avoid that happening?
I slow to a crawl when transitioning from one colour of pavement to another, but let's face it, a 1" high chunk of anything acts as a pretty good wheel chock with a 12" diameter tire up front.
3" deep gopher holes or ruts? expect trouble.