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

[rzbill]

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

I put 4 washers under the heads of mine (1/4" total) such that the bolt ends are flush with the inside of the fork. I hope others are doing the same, and ignoring what drawing C1 says to do.

[DaleB]

I will share my totally unqualified opinion simply as someone who was going to build a nose dragger, contemplated the ASA modifications, and ultimately decided to avoid the entire debate. Take it for what it's worth, which is every penny you're paying for it. For the record, this is not me saying "tailwheels rule", nor is it me saying the ASA modification is either good or bad.

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

I'm no mechanical engineer, although I was raised by one. Knowing the history of the RV nose gear, it seems to me that changing the gear leg and/or mount to give more of a tendency toward vertical deflection and less toward horizontal deflection might have some positive results. Looking at other designs (Cirrus, Grumman) shows how other designers have done it. After reading discussions like this for a couple of years, I still can't figure out for sure if proper pilot technique can guarantee no incidents, or not. Although this issue was not the only influencing factor, I did decide to opt out with an RV-7 - so now I'll butt out.

[gerrychuck]

Originally Posted by Snowflake

From what i've read about the Anti-Splat device, I understood that it would prevent tip-overs by removing the tendency for the gear to fold under... But that it wouldn't necessarily prevent a collapse in some situations. It sounds like it did what it was expected to in this situation.

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

[Don]

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

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

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

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

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

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

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


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

[catmandu]

Originally Posted by rzbill

Y'know.....
I don't remember any commentary in any of the nosewheel failure threads about the length of the big allen screws . . . .

This is what online forum 'discussions' have done to me: my mind is spring loaded to expect a fight. I read the title for you post (Allen protrusion) and I thought you were going to comment negatively on Allan's insertion into the discussion with his comments in post #51!

[Kahuna]

Originally Posted by Don

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

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

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

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

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

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

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


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

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

[plehrke]

Originally Posted by Don

Thanks in advance for any comments and suggestions....<g>

You need weight on nose gear.

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

[Bevan]

Some more data you could also collect:

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

approx. CG of aircraft at the time of the incident

tire pressure

wheel pants on/off

previous damage history

total hours on aircraft

Grove wheel as another bearing type

nose gear leg re-enforcement type if any, wood, fiberglass, other

[Kahuna]

Originally Posted by Kahuna

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

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

[jay.pearlman]

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