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  #1  
Old 11-13-2011, 09:30 AM
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Webb Webb is offline
 
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Default Tail Wheel vs Nose Wheel accident numbers

Lot's of discussion on flip overs of A's lately. Also its been said that a ground loop is not a question of if but a question of when.

Can any of you computer gurus pull any data to provide a factual comparison between the two? Would also help to know the number of nose draggers vs tail draggers for percentage comparison.
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  #2  
Old 11-13-2011, 10:22 AM
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LeeM_2000 LeeM_2000 is offline
 
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Yeah, I did this research last year. I was mostly concerned with attempting to figure out the impact of the A-model doink-over, but you can see that accidents are fairly even between the two configurations given my considerable margin of error.

According to what I have been able to pull up from the NTSB database from 1/1/2000 to 9/25/2010:

I counted 300 total RV accidents broken down as follows:
66% non-A models
34% A models
32% (95) of the total RV accidents were fatal
57% (54) non-A of the fatal accidents--2 of those were nose-overs
43% (41) A models of the fatal accidents--4 of those were nose-overs
38% of the tricycle accidents ended with a nose-over
23% (70) of the RV accident reports have the term "nosed over" in the narrative. 'Nosed over' may not be an official catch-all, but it appears to be the term used when the airplane rotates about the nose and comes to rest inverted. Also, nearly all of the "nosed over" reports mention nose gear failure.
17% of all RV accidents reported were A model doink-overs

Nose-overs are broken down as follows:
71% (50) A models
29% (20) non-A models

Conclusions:
This is not an exact science and it can be difficult to tell the apples from the oranges when reading accident reports.
Tri-cycle gear RVs are not significantly less accident-prone than conventional gear RVs. That is, unless there are fewer tail dragger RVs flying than tri-cycle RVs. I sort of assumed a slight edge to the tail dragger.
Nosegear failure contributes to 17% of all RV (tail dragger and nose dragger combined) accidents and 1% of the fatal accidents
Rollover accidents in RVs are not particularly deadly, always but substantially damage the airframe.
Rollover accidents occur more that twice as frequently in A model RVs as in non-A model RVs and rollovers are twice as deadly in A model RVs.
Most of the nose-overs happen after botched landings, but a fair number are due to engine failure and related off-airport landings.
Stipulations:
I don't know the total number of flying RVs and how many of each type there are.
Not all accidents are reported to the NTSB.
Model names can be misrepresented by the reports.
I did not consider other accident causes and a fair number cite improper landing technique.
There is a lot more to be gleaned from the NTSB reports, but this is all I had time for. If you don't like my numbers, go figure your own.

Last edited by LeeM_2000 : 11-13-2011 at 03:42 PM. Reason: Typo
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  #3  
Old 11-13-2011, 11:20 AM
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Andy Hill Andy Hill is offline
 
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Default

Lee...

I think that is a pretty good analysis, especially since you "caveat" where the weaknesses might lie.

One point:
Quote:
That is, unless there are fewer tail dragger RVs flying than tri-cycle RVs. I sort of assumed a slight edge to the tail dragger.
My guess would be more than a "slight edge" to the taildragger? Vans might be willing to furnish you with that information?

Overall, I don't think it important to narrow this down to exactly which has more accidents. I think it generally accepted that the taildragger should have a significantly higher % of accidents, particularly landing (even takoff) ones, and taxiing. If the nosedragger % is even approaching that of the taildraggers, there is a significant problem.

It will take a good number of installations, and over a good period, to see it the "anti nose splat" mod works, but at least you have provided a starting point as it becomes available...

Andy
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  #4  
Old 11-13-2011, 11:52 AM
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Jerry Cochran Jerry Cochran is offline
 
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Default Ahem....

Quote:
66% non-A models
44% A models
Is my math wrong or does that add up to 110%?

Just sayin'
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  #5  
Old 11-13-2011, 02:03 PM
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RV8iator RV8iator is offline
 
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Default Another Caveat

Doesn't break down RLOC accidents as compared to all the others.

Statistically, only accidents that happen during T/O or LDG phase should really matter in this question.

If a tail dragger augers in because of a spin it doesn't have a lot to do with the configuration...

Just sayin...

this bunch of numbers doesn't begin to tell a story.
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  #6  
Old 11-13-2011, 03:41 PM
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LeeM_2000 LeeM_2000 is offline
 
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Quote:
Originally Posted by Jerry Cochran View Post
Is my math wrong or does that add up to 110%?

Just sayin'
Yeah, the 44% was a typo. It should have been 34%.

I just did the same search of the NTSB database and came up with 11 more accidents than I found a year ago when I did this little exercise. I also counted up the 'A' models and the revised percentage worked out to 33.4%. Take it all with copious amounts of salt granules.
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  #7  
Old 11-13-2011, 04:50 PM
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Russ McCutcheon Russ McCutcheon is offline
 
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""Also its been said that a ground loop is not a question of if but a question of when"".

I can't answer your question but I will say I have heard this saying before and I don't agree. I also don't agree that you have to land gear up at any point if you fly retract.
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  #8  
Old 11-13-2011, 05:22 PM
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Default

Quote:
Originally Posted by Russ McCutcheon View Post
""Also its been said that a ground loop is not a question of if but a question of when"".

I can't answer your question but I will say I have heard this saying before and I don't agree. I also don't agree that you have to land gear up at any point if you fly retract.
I have always been very irritated by both of those old sayings, mostly because they are not true.
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  #9  
Old 11-13-2011, 06:10 PM
C-GRVT C-GRVT is offline
 
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Default lots of accidents!

What strikes me is what seems to be the large number of accidents - 300 accident aircraft out of a total fleet of some 7000, some of which don't have or haven't yet seen many hours. Not good.
This "Safety" subject is deserving of a lot more attention and effort by each of us who love this RV thing.
Bill Brooks
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  #10  
Old 11-13-2011, 07:36 PM
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N941WR N941WR is offline
 
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Default Something else to think about

Flip over or ground loop?

I would much rather ground loop than flip over. From what I have read on the A-overs, they can and do happen at any speed and I'm sure ground G-loops can happen at any speed.

That said, I would much rather be in a ground loop than a nose over. Most ground loops end with some damage but the plane coming to a rest upright.

Besides, with proper training there is no reason to have a ground loop.
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