Nose Job

Below is the link to a(nother) flipped RV9A

http://www.wcnc.com/news/local/EMS-tending-to-pilot-at-Rowan-Co-Airport-203411341.html

After looking at this I installed a wood nose gear stiffener wrapped with glass/epoxy as suggested in VANS documents. I now have some doubt about this procedure as the leg is now completely stiff and has virtually no suspension range.

I also like to refer to a statement attributed to B Rutan in this context:

"urged the aviation industry not to defend aircraft designs, but to question them constantly as a method of improving them. Defending what may be a flawed design is no way to treat customers"

Another opinion by a high time RV owner was: "If you break the nose gear you can't fly properly - don't worry about it"

Comments?

See:

http://www.vansairforce.com/community/showthread.php?t=98734

-or-

http://www.vansairforce.com/community/showthread.php?t=98704

Both of those threads are likely closed because if you do a quick search you'll see this horse has been severely beaten!

Cheers,
Stein

RijkersJ said:

Below is the link to a(nother) flipped RV9A

http://www.wcnc.com/news/local/EMS-tending-to-pilot-at-Rowan-Co-Airport-203411341.html

After looking at this I installed a wood nose gear stiffener wrapped with glass/epoxy as suggested in VANS documents. I now have some doubt about this procedure as the leg is now completely stiff and has virtually no suspension range.

I also like to refer to a statement attributed to B Rutan in this context:

"urged the aviation industry not to defend aircraft designs, but to question them constantly as a method of improving them. Defending what may be a flawed design is no way to treat customers"

Another opinion by a high time RV owner was: "If you break the nose gear you can't fly properly - don't worry about it"

Comments?

Click to expand...

RijkersJ said:

Another opinion by a high time RV owner was: "If you break the nose gear you can't fly properly - don't worry about it"
Comments?

Click to expand...

Not always ... but about sums it up ...

RijkersJ said:

After looking at this I installed a wood nose gear stiffener wrapped with glass/epoxy as suggested in VANS documents. I now have some doubt about this procedure as the leg is now completely stiff and has virtually no suspension range.

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That's generally to fix a different problem.
Not quite the right solution...
Have to consider what happens when the stress get focused somewhere else...

Flipped Out

Havent heard of anyone flipping with the Aerosplat installed.
Bob

Flipped Out

Havent heard of anyone flipping with no reason.

6 Gun said:

Havent heard of anyone flipping with the Aerosplat installed.
Bob

Click to expand...

At least one still bit the dust... and the jury is still out on longtime stress issues.
Hope all of the stress focused at the engine mount doesn't become problematic.

accident

Just a few things noticed in the pictures.
There is a nice rut in the grass like the plane ran off the runway and it was wet or muddy.

No wheel pants or paint. A brand new project completed or someone purchased it just finished. Sad. I hope this isn't another case of inadequate transition training.

Van's says front gear is a taxi gear only.
I add that my airplane is a no brakes airplane. The added weight on the front gear is responsible for the nose gear to dig in the grass. I consider the -9A an airplane which lands in places where there is no need to push brakes. It is possibile to land it with out braking in 600 meters grass airstrips (1800 feet). That is where my airplane is located.
Having said that, I installed antisplat job.
And hope not to flip ever.
Do not brake!

6 Gun said:

Havent heard of anyone flipping with the Aerosplat installed.
Bob

Click to expand...

There was one reported here last year - we never saw pictures, but the sources were multiple and reliable.

Proving only that no matter how many devices you might have, you STILL need to fly the airplane properly.

Nose Job!

While training for my PPL in a 172, my instructor told me on several occasions to keep the weight off the nose wheel or this thing will "wheelbarrow off the runway and fold the gear up". My 172 Firewall had been repaired before I purchased it! Just my thoughts, but I like what Paul said.

Nose job (2)

Further to my attempt to generate a discussion on the subject I looked at my RV6A, took some measurements, and did some brief calculations.
My conclusion is this;
1. VAN?S documents indicate a maximum nose wheel weight with forward CoG of 375 lbs. (?flight prohibited?) This is 23% of gross and as such higher than established design criteria. Furthermore some pilots/builders may not be aware of this limit or ignore it.
2. The steel of the leg is 6150 that has been hardened/normalized. I do not know the exact final temper in this area of the leg but the steel properties are 400Mpa annealed and 600Mpa hardened. Assuming a yield strength of 500Mpa in the bent section the moment generated by the arm of the trailing link at VANS figure of 375 lbs results in a stationary stress approaching 50% of this figure (taking into account curvature factor 1.5). If you add to this the deceleration ? regardless how it is generated, i.e. without braking on soft grass ? of 0.1 G resulting in an additional load of 100lbs. Add some dynamic loading from ground roughness, wheel bearing friction, harmonics, etc. and the stress quickly approaches the yield limit in the bottom part of the leg. That is with a good landing. Clearly a bouncy landing or significant braking (0.3 G?) could multiply the load significantly. The aluminium fork appears to be more than strong enough so that is not a factor. The failure mode therefore appears to be bending of the leg just above the swivel resulting in lock-up of the wheel and/or digging in of the nose of the fork. Subsequently this then translates into bending of the centre portion of the leg and possibly nose-over.
3. The solution of Antisplat addresses the bending of the centre section but does not have an effect on the bottom part where the problem originates. The positive aspect is that their bracket only affects the bending back and not the flexibility from vertical loading. At a cost penalty in $$ and weight I must conclude that it does not address the core of the problem. Similarly the installation of a wood/epoxy gear-leg stiffener does not reinforce the bottom part of the leg and actually increases the dynamic loading as the leg becomes stiff.
4. The bottom line is that I do not have a simple solution other than to rely on pilot skill and avoiding the brakes. Short of a redesign away from the trailing link, the solution should in my opinion be sought in a reduction of the nosewheel load, e.g. pilot/builder controlled weight distribution/Gross/CoG, and moving the mains slightly further forward. The diameter of the bottom part of the leg (bend section) could be increased without a material effect on flexibility and weight. It is presently tapered to 1? at the swivel socket and increasing the bottom end to 1-1/8 would increase the strength by 42%. Other than that a free turning and balanced wheel and some other form than the wood stiffener for damping of harmonic vibration of the leg might have a positive influence.
5. A comprehensive improvement is not a simple problem that can be addressed by the builder individually and in my opinion should be considered as a further development by VANS. Alternatively you could order a custom leg from Langair and design your own profile, with a double reverse taper, on the basis of weight and CoG criteria of your particular airplane.
Hope I did not bore you all with this long story

your engineering analysis matches what we had to find out/had to have calculated during the registration process over here. theoretically, the weak link should be just above the bend on the lower gear leg.
problem is, the dynamics of reality seem to clearly proof theory wrong.
practically all folded gear legs i have seen, kept their original bend/lower shape, yet had severely bent where the antisplat brace tries to picks up.
i have to admit we got the brace a while ago but because of a mix between not wanting downtime, not having a workshop currently with most tools stored away required for fitting the new fairing and having to go through a paperwork modification process, we have so far held off the installation.
i tend to agree with the "fly the aircraft properly and you're fine camp." however, the margin is clearly thin, we keep off of any grass runways and any level of piloting is useless in case of an excursion due to brake failure or an off airport landing.
this alone had me going for a -14 were i to start over today...

bernie

Have read with interest the attempts to analyse the failures of the nose gear in 7A and 9A aircraft.

RijkersJ - you throw maths at the problem... but have you the correct physical model you are looking at ? Certainly some of the forces you talk about are present.
flyvans.com - sorry but reality, in my opinion, proves the theory correct if you use the correct physical model and apply basic simple engineering principles.
The maximum moment, due to forces at the nose wheel, occurs at the point of effective fixity of the strut. That happens to be at, or close to, the strut entering the engine bracket. (exactly where failures and bending are occurring.)

The actual weight on the nose wheel (it is a vertical force) is not such an important parameter... if it was so important the strut would bend forward into the propeller. Clearly the major effect is the horizontal force created when the nose wheel is significantly retarded by digging into a hole or similar cause. With the wheel being stopped from moving forward and the momentum of the forward moving aircraft - the force is horizontal in the wheel strut. The moment on the strut at the point of fixity is too great and it bends backwards from a point close to the body of the aircraft (as it should) and .. oops Over I go ! The point of effective bending of the strut depends on the strength of the strut - being tapered a little - it may not be in the cowling.

The antisplat brace tends to address this problem .. and is certainly on the right path...

The speed of the aircraft, when the wheel is effectively retarded, will be the main consideration in determining if the strut bends backwards.

RijkersJ said:

Another opinion by a high time RV owner was: "If you break the nose gear you can't fly properly - don't worry about it"
Comments?

Click to expand...

RVnoob said:

Haven't heard of anyone flipping with no reason.

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Camillo said:

Van's says front gear is a taxi gear only.

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I still have in mind the image of a short video clip, I think posted here on VAF, of an -A model nose-over caused by merely taxiing on asphalt and rolling over a lip in the pavement...something no one would question in any other aircraft. I've applied all 3 Anti-Splat "fixes" for the nose gear, but still wonder what risk I will have when I fly it (working on Firewall-forward parts). Thinking that it's always caused by some incorrect pilot technique, thus, can't happen to me, is unsubstantiated IMO.

Buggsy2 said:

I still have in mind the image of a short video clip, I think posted here on VAF, of an -A model nose-over caused by merely taxiing on asphalt and rolling over a lip in the pavement...something no one would question in any other aircraft. I've applied all 3 Anti-Splat "fixes" for the nose gear, but still wonder what risk I will have when I fly it (working on Firewall-forward parts). Thinking that it's always caused by some incorrect pilot technique, thus, can't happen to me, is unsubstantiated IMO.

Click to expand...

If you install the nose faring too low and close to the tire, the fiberglass can catch on a raised surface and be pushed under the tire causing the tire to drag (roll up on the inside of the faring) and if the drag is enough, the fork will tilt enough to dig in and cause failure.

Keep the nose wheel rolling and you almost eliminate the problem.

1. Understand the bearings and axle past problems, and correct them.

2. Maintain air pressure..... I keep mine at 40#.

3. Allow more tire exposed under the faring so it has a chance to roll over an one inch lip.

4. Fit the faring with at least a finger gap between it and the tire sides. A little more front and rear. You should never see any scuffing under the nose of the faring.

5. Learn to fly (maintain altitude and do turns) at 65 mph..... so you can touch down at stall speed... or JUST above. All to reduce ground roll speed and the need to brake.

I believe the pilot in this case blamed "a problem with flaps"

?He was telling people there was something going wrong with flight controls. He had issues with his flaps. He said either they stuck or he had some problems with them,? the sheriff said.

That tells me there's a much bigger factor in this accident than any perceived nose gear flaw.

LettersFromFlyoverCountry said:

I believe the pilot in this case blamed "a problem with flaps"

?He was telling people there was something going wrong with flight controls. He had issues with his flaps. He said either they stuck or he had some problems with them,? the sheriff said.

That tells me there's a much bigger factor in this accident than any perceived nose gear flaw.

Click to expand...

I take it you mean he allowed himself to become distracted by the flaps? Because as long as the flaps were equally stuck (no differential flaps) they shouldn't have caused the subsequent poor landing and nose-over.

Buggsy2 said:

I still have in mind the image of a short video clip, I think posted here on VAF, of an -A model nose-over caused by merely taxiing on asphalt and rolling over a lip in the pavement...something no one would question in any other aircraft.

Click to expand...

Must have been a pretty fast taxi....

I can't stand it

This was not a nose gear failure.

Thats all I'm sayin'

rzbill said:

This was not a nose gear failure.

Thats all I'm sayin'

Click to expand...

+1

Thank you!

rzbill said:

This was not a nose gear failure.

Thats all I'm sayin'

Click to expand...

So now if we have a flap problem, we might flip our "A" models???? In the photo, looks like full flaps, both at the same location. That should have not caused a flip unless he was distracted trying to retract for a T&G.

Looking at the nose wheel, it sure does not look like mine. It looks like a nose gear failure after he left the hard surface.

That's all I'm saying........ at this time.......

Sure.

Same as a head on is a front end failure of a car.

I just finished transition training to prepare for my first flight. My CFI and I did 10 take offs and landings to full stop.

Before the first flight, he stressed "treat the nose gear as if it is made of balsa wood". Treat every Take Off and Landing as a soft field. Nose up and off the runway with aft pressure on take off roll and don't let it down till the airspeed can't hold it up on landing, then keep aft pressure on the stick.

I don't want to speculate on what did or did not cause the latest incident. As it was a new airplane, I feel for the pilot. Can't imagine how terrible that would be after just completing the build.

My take away is to follow my transition training and treat the nose gear as if it were made of silly putty! Fly to the best of my ability, and I installed a nose job for just a bit of insurance.

Buggsy2 said:

I take it you mean he allowed himself to become distracted by the flaps? Because as long as the flaps were equally stuck (no differential flaps) they shouldn't have caused the subsequent poor landing and nose-over.

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Right. I wrote about it on the blog. The claim suggests there was a lot going on here that betrays the suggestion of a simplistic cause -- "there's that nose gear going again"

By the way , and forgetting about this tragedy for a second, what is the minimum taxi or rollout speed that a typical RV has to be going to flip over? This is well beyond my capacity to figure but I'm sure that expertise is right up in somebody's wheelhouse on VAF, from what I've seen. Given the typical weight of, say, a 7A and a rough COG, what would it take -- in terms of speed -- to flip?

pmccoy said:

I just finished transition training to prepare for my first flight. My CFI and I did 10 take offs and landings to full stop.

Before the first flight, he stressed "treat the nose gear as if it is made of balsa wood". Treat every Take Off and Landing as a soft field. Nose up and off the runway with aft pressure on take off roll and don't let it down till the airspeed can't hold it up on landing, then keep aft pressure on the stick.

I don't want to speculate on what did or did not cause the latest incident. As it was a new airplane, I feel for the pilot. Can't imagine how terrible that would be after just completing the build.

My take away is to follow my transition training and treat the nose gear as if it were made of silly putty! Fly to the best of my ability, and I installed a nose job for just a bit of insurance.

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Good on you Pat! I wish you the best.

For the very reason your CFI explained above....and the fact that I want the taildragger chllenge....I have decided to put the little wheel in the back.

snoop9erdog said:

Good on you Pat! I wish you the best.

For the very reason your CFI explained above....and the fact that I want the taildragger chllenge....I have decided to put the little wheel in the back.

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Other than, perhaps, fear of the transition training, and given the prevalence for the A models to flip, why do people want an A model?

Honest question. I bought a TD because I wanted a TD, what is the benefit of an A model other than avoiding learning how to fly a TD?

And please, don't spout off about being able to land in an X wind. I'm no Chuck Yeager and I fly my TD on days when pretty much everything else is tied down. That is simply an matter of obtaining skills and confidence.

walkman said:

why do people want an A model?

Honest question.

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Even so, this probably belongs in the unending debate section and not as a thread stealer.

why do people want an "a" model?

Personally, because my wife has supported this project from idea stage and she wants an "A" model. She has sat in both and in the rear of an 8 and prefers the "A". We all know what it means to keep the wife happy! Cuz if she ain't happy, I ain't happy!

Ironflight said:

There was one reported here last year - we never saw pictures, but the sources were multiple and reliable.

Proving only that no matter how many devices you might have, you STILL need to fly the airplane properly.

Click to expand...

...I feel a need at this point to chime in on this, in hopes of dispelling any undo fears or misconceptions prior to them growing out of proportion. To date 4/23/2013 there has been only one flip-over with our product "The Nose Job" in place. The owner of this particular aircraft was a fellow named Mike Kullenberg and he was one of our first group of customers. He stated all the information here on this forum and contends that our unit saves the bacon several times for him, this incident not withstanding. I am including his write-up here below in this post so it doesn't get misconstrued or overlooked. We have seen a number of incidents that would most assuredly have resulted in flip-overs were our product not in place. These were all repairable and major damage or loss of the airplanes didn't occur. All the owners and pilots were convinced of this and told us so. With the thousands of our products and services now in use, the safety record appears to be emerging on it's own. At any rate, if you are interested here is the information in regards to this accident from the horses mouth. Regards all, Allan...
.
.........POSTED 10/7/2012
OK, I am the guy that did the nose over. This will be my only post on this subject, as I have moved on to a different airplane, and no longer look at this forum.

First I will say the the Anti-Splat did EXACTLY what it was supposed to do, but nothing was going to keep the airplane right side up in this circumstance.

I had recently extended the runway about 400 feet, and there was a transition area between the old part with good grass and the new section that still had an uneven ground cover. It had rained two days previously. My inspection of the runway before departure did not indicate any discernible issues. The incident landing was normal in every way until the nose wheel crossed over into the new section at no more than 5 to 10 mph. I felt the airplane decelerate rapidly, and then very slowly it started to rotate over. I briefly even thought that the airplane might come back down on the gear, but no such luck. I will always believe that the Anti-Splat slowed the rate at which it went over, thus giving me a much less injurious ride. I think that is evidenced by how little damage was done to the cowl, wings, and the tail group. The only part of the airplane that suffered was the canopy and the roll bar structure, but there it bent stuff in an expensive way.

The nose wheel had dug a furrow into the soft dirt about 4 to 5 feet long getting deeper the entire way until the ditch was about 6 inches deep. The nose wheel stopped right there and over it went. I'm not so sure that a 172 or Cherokee would not have ripped off or severely bent the nose gear in the same situation. The true downside of the Vans nose gear is the spring steel. It is a great spring.

The end game is that I was OK, pride wounded and a bit sore, but otherwise OK. The insurance company decided after some repair quotes that we should total it. I agreed, and started looking for another one (taildragger only). I could not find one I liked or could afford, so now I have a Maule.

I looked at the ad on eBay, and do not believe that Wentworth has a good handle on the damage. They have never personally seen the airplane to my knowledge, and it is still in Cheraw where the recovery team took it. All I will say is that it will not be as simple to repair as their ad indicates. BTW it was an Titan IO-360 with a CS prop, and the weight and balance was within Vans parameters. When I was in it (big guy) the airplane was exactly in the center of the cg range. Since then I have finished grading and grassing the remainder of the strip, and now it would not be a problem.

Bottom line is that ANY airplane can be damaged if the nose wheel gets buried. I do not (nor should anyone on this forum) blame the Anti-Splat for any part in this. In fact it probably saved me from some more serious injury.
__________________
Mike Kullenberg
Dantzler Plantation
Providence, SC
RV-9A N409G
In paint at Glo-Custom new number is N573PM
ECI IO-360 CS
Dynon Skyview

pmccoy said:

...My take away is to follow my transition training and treat the nose gear as if it were made of silly putty...

Click to expand...

This past Saturday I attended a fly in at Mojave. I was parked with a pretty good view of the 7100 x 100 foot runway 08/26 and was amazed at the poor showing of skill this day. The weather was pretty benign, and yet plenty of people had a hard time getting stopped for the taxiway located 3000 feet from the approach end. However, the worst performance by far was someone in an RV-6A who touched down on the nose gear first, then porpoised several times before getting it under control. Each time he ricocheted off the nose leg, I expected it to fold. And yes, this person couldn?t manage to get it stopped before the 3000 ft mark either?

Frankly, I?m shocked we don?t see more accidents in the news than we do.

Allan, It sure would be a plus if we could see what shape the gear leg ended up in.

Much of this speculation doesn't really matter if folks don't have all the facts as to the incident. In this case (like MANY previously) there were/are extenuating circumstances where the "failure" was likely an effect, not the cause here. Luckily nobody was hurt badly here, but that still doesn't mean anyone should jump to a conclusion on the cause without knowing the facts.

Just speaking hypothetically here, but if someone dropped in an airplane so hard they had a prop strike....would it be surprising to see damage to a nosewheel on any trike airplane? Not saying that is the case here, but it has been the case on some "incidents" in the past. This is exacerbated by the fact that the PIC's rarely come out after the fact and openly publish the details (and others don't want to publish details for fear of embarrassing the pilot, or causing an argument, or getting in the way of an investigation, etc..), so many people are left hanging only to surmise what they can based on photographs or other anecdotal information (not first hand info). I don't have a solution to that, nor saying every and all discussion is bad, just sayin...

I'm also not defending or criticizing either side in this debate, merely pointing out that a debate on the end result without facts of the cause is somewhat of a dubious undertaking.

Just my 2 cents as usual!

Cheers,
Stein

Nose Job(3)

I did some digging in old posts and realized that this issue has been beaten to death in the past. Most is not very constructive but posts by RAIZ stood out. In the meantime nothing has changed or developed.
Called Langair concerning a custom leg and he declined - liability issues are probably stiffling any such attemps and I understand

I am not happy but the result is probably a good warning and make me (and others) more carefull

Regs

Toobuilder said:

This past Saturday I attended a fly in at Mojave. I was parked with a pretty good view of the 7100 x 100 foot runway 08/26 and was amazed at the poor showing of skill this day. The weather was pretty benign, and yet plenty of people had a hard time getting stopped for the taxiway located 3000 feet from the approach end. However, the worst performance by far was someone in an RV-6A who touched down on the nose gear first, then porpoised several times before getting it under control. Each time he ricocheted off the nose leg, I expected it to fold. And yes, this person couldn?t manage to get it stopped before the 3000 ft mark either?

Frankly, I?m shocked we don?t see more accidents in the news than we do.

Click to expand...

Sad but true... it is actually pretty common on any day.

I could add a lot to this but I will keep it short. I have had a Private Pilot license for the past 7 plus years sport before that and have flown with insert my Dad brother uncles cousin and about any others since the early to mid 70's. In other words a lot of time in all types. The last 9 years in a Cub and than a Citabria. Have been a truck driver and mechanic,Police and pretty much an all round has been there and done that.(not good at any one thing and good at nothing). Sums me up pretty well.
I have seen over my 56 years in all types of industry that if it can be done it will! That is why we have Lawyers (sorry) and that big printing on anything (Warning) Eula, if you do this etc. will happen. So with that said Just take it easy and treat it like the most important person in your life and it will more than take care of you! It really doesn't matter if it's a straight 6,7,8 or whatever even an A model. Do not try making a stop if your porpoising down the runway you get to do a go a round and make that the best landing this time.
Scott

SteinAir said:

but that still doesn't mean anyone should jump to a conclusion on the cause without knowing the facts.

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Well, no,of course, you're right. It's just that the sheriff quoted the pilot as saying the problem was the flaps. Which opened the door.

Which brings up another piece of advice in these situations: don't say nuthin.