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  #21  
Old 07-25-2017, 09:55 PM
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Infidel Infidel is offline
 
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One would think there would be more photos associated with an investigation like this. I've taken more photos of simple vehicle collisions than what is available in this report.
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  #22  
Old 08-10-2017, 01:13 PM
Ulrich Ulrich is offline
 
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I noticed the NTSB report mentioned the 6G limit and weight of 1800#! Van's states the 6G gross weight is 1600#.. putting this one at or over gross (weight was estimated). Anytime you have two up acro..you are going to be close to or over gross and have to keep the Gs down. Have fun, a lot of fun, but be safe!
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  #23  
Old 08-10-2017, 01:54 PM
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Default Tail question

Bill, I'm would guess the obivious that the tail separated first and thus the reason it's the fartherest away from main crash site. As to the reason of why it came off, well, I guess even the NTSB didn't want to speculate. The fact that it departed first is interesting. I wonder how many occurances of tail separations by type have occurred. My memory isn't what it used to be but I suspect the -3,-4,-6, -9, and -10 do not have the same frequency. If the tail separation causes can't be determined, would it be insane to assume that the data will get better over time without any changes ( that is, less tail separations occurances)?


Quote:
Originally Posted by BillL View Post
Is there a technical reason for the VS with upper rudder attached to have settled to earth well in advance of the HS (L & R)? The report states the HS failed first, separated (and from the debris field) landed closer to the main site.
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  #24  
Old 09-02-2017, 07:34 PM
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Thermos Thermos is offline
 
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Quote:
Originally Posted by grubbat View Post
I wonder how many occurances of tail separations by type have occurred. My memory isn't what it used to be but I suspect the -3,-4,-6, -9, and -10 do not have the same frequency.
I've kept track of structures-related accidents in RVs in general, but my focus is obviously on the -7.

There have been two other RV-7/7A tail separation accidents in recent memory that appear to be similar to this one. One was a Canadian RV-7A, C-GNDY, which was investigated by the Canadian Transportation Safety Board. A later one was an RV-7A, N174BK, in New Jersey, which was investigated by the NTSB. Both of those accidents had much more data available from which to draw a conclusion, so in this case I think the NTSB did the best they could with what they had.

At the risk of being accused of speculation by a mod, all three of these accidents were "big tail" RV-7As, i.e., with RV-9 rudders, and according to the accident reports, were estimated to be well above Vne (20-35 kts) when structural failure occurred. The RV-7's rear fuselage and stabilizer structure is very similar to the RV-8, and given the relatively greater use of the -8 for aerobatics, and the probability that some have been past Vne, should we expect to have seen similar accidents in the -8? Of course, that question leave a lot of factors out like build quality, pilot training, usage spectrum, sample size, etc.

I'm forced to wonder if the combination of the -7 VS and -9 rudder may be less robust than with the original -7/ current -8 rudder, but the bottom line is still to fly your airplane inside the design speed/weight/CG envelope.

Dave
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Last edited by Thermos : 09-02-2017 at 07:42 PM.
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  #25  
Old 09-02-2017, 07:50 PM
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catmandu catmandu is offline
 
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Very astute observation, Dave. Thanks.
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  #26  
Old 09-02-2017, 08:19 PM
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RV8JD RV8JD is offline
 
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Default Rudder Differences

Many of the differences in the rudders are covered in this thread:

http://www.vansairforce.com/communit...d.php?t=146673
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  #27  
Old 09-03-2017, 08:09 AM
Mr Grinch Mr Grinch is offline
 
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Quote:
Originally Posted by RV8JD View Post
The NTSB does a better job of investigating GA accidents now than they did in previous decades, but not nearly as well as commercial airliner accidents, train accidents, or bus accidents. They just don't commit (or have) the money and resources necessary for an in-depth investigation of GA accidents. Some other country's accident investigation organizations often do a good job on GA accidents (Canada and Australia come to mind).

But it's to Mr. Nixon's credit (and the NTSB) that corrections will be made. My wife and I were in a partnership with a friend (Dave) and his wife in a Rolladen-Schneider LS1-f sailplane. In October 1978, my partner was flying the sailplane and was involved in a midair collision with a Piper Saratoga on a CAVU day. Dave and 4 people in the Saratoga perished in the accident. The NTSB did a quick investigation, and there were several factual errors in the final report. As co-owner of the sailplane, I pointed these out to the single investigator assigned to the accident. He was adamant that there were no errors and would not change a thing. One that sticks in my mind: The investigator misidentified the Variometer, which is a sensitive rate-of-climb indicator, with a "g"-meter. I explained what a Variometer was, and told him the there was no "g"-meter installed in the sailplane. He was adamant that he knew what a "g'-meter looked like and that (Variometer) was a "g"-meter! I should note that in this case the factual errors did not affect the Probable Cause finding (i.e., The pilots of both aircraft failed to see and avoid each other.)

So I'm always a little bit skeptical of NTSB GA accident reports, but not so much of commercial airline accident reports, which are usually well investigated.
They make mistakes and grand leaps in airline accidents as well. Politics, bias, lack of experience in operations, etc.
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  #28  
Old 09-03-2017, 01:50 PM
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Quote:
Originally Posted by RV8JD View Post
Many of the differences in the rudders are covered in this thread:

http://www.vansairforce.com/communit...d.php?t=146673
I completely missed this thread, Carl - thanks for pointing it out and thanks for sharing your flutter/aeroelasticity knowledge!

Dave
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  #29  
Old 09-03-2017, 06:26 PM
sblack sblack is offline
 
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Quote:
Originally Posted by OkieDave View Post
This. Also, if there's ever a lawsuit, the discrepancy is going to be highly relevant. That's the sort of thing defense attorneys dream of.
I recall reading, though I don't recall why, that NTSB reports are not admissible in a lawsuit. Is it because they are considered heresay? You have to bring in an expert witness to testify directly to the available evidence.
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  #30  
Old 09-03-2017, 06:33 PM
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RV8JD RV8JD is offline
 
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Quote:
Originally Posted by sblack View Post
I recall reading, though I don't recall why, that NTSB reports are not admissible in a lawsuit. Is it because they are considered heresay? You have to bring in an expert witness to testify directly to the available evidence.
You may have missed page 2 of this thread.

http://www.vansairforce.com/communit...8&postcount=19
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RV-8, 1932 Tach Hours
(Pic 1), (Pic 2), (Pic 3) - Sale Pending
Glasflügel H-201B Standard Libelle, N564NS - Sold
Rolladen-Schneider LS1-f, N61MP - No longer owned

Last edited by RV8JD : 09-03-2017 at 06:37 PM.
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