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NTSB Final Issued for N307AB

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.
 
From the NTSB Report:

"Control continuity was established from the cockpit controls to the elevators and the right aileron. The left aileron controls cables were fractured and had a splayed, broom-strawed appearance, consistent with tension overload. The rudder cables were jammed somewhere in the fuselage, and control continuity could not be established, but the cables remained attached at the rudder and the pedals."

Not quite right!
I'll say. That's an amazing error. Perhaps a copy/paste error from another report?
 
Error to be corrected, now let's focus on the issues.

I just spoke with Albert Nixon the chief investigator for this report. I pointed out the error regarding the controls cables vs control rods. He was very appreciative and said he will get it corrected in all the locations in the report. It might take a few days to get all the processes executed, but will get through the system right away.

FOLLOW UP EDIT: The NTSB report was modified on August 9th.
 
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If I read it right, the VS and upper rudder was found at the beginning of the debris field but there was nothing specific about the condition of those components, nor the attach points seen in the report. Indications of how they separated from the aft fuselage?

The separation of the upper rudder and VS from the lower rudder might suggest an examination of the inboard portion of the elevators to see if there was contact with the lower rudder (deflection into either elevator)?

Just 1st impressions. But they seem to be associated with the earliest breakup events.
 
I just spoke with Albert Nixon the chief investigator for this report. I pointed out the error regarding the controls cables vs control rods. He was very appreciative and said he will get it corrected in all the locations in the report. It might take a few days to get all the processes executed, but will get through the system right away.

Getting it corrected is one thing. Finding out why it's wrong is another. If the examiner looked at the wreckage, thought he was looking at aileron cables, and proceeded on that assumption, then one might question his competency at evaluating the rest of the incident.
 
Getting it corrected is one thing. Finding out why it's wrong is another. If the examiner looked at the wreckage, thought he was looking at aileron cables, and proceeded on that assumption, then one might question his competency at evaluating the rest of the incident.

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.
 
If I read it right, the VS and upper rudder was found at the beginning of the debris field but there was nothing specific about the condition of those components, nor the attach points seen in the report. Indications of how they separated from the aft fuselage?

The separation of the upper rudder and VS from the lower rudder might suggest an examination of the inboard portion of the elevators to see if there was contact with the lower rudder (deflection into either elevator)?

Just 1st impressions. But they seem to be associated with the earliest breakup events.

I have been mentally processing, so may be wrong here - - the report indicates that the HS failed first. Assuming that is correct, I am guessing it was sudden and unlikely that both sides failed perfectly in harmony. Given that one side might fail suddenly, there would be a very high release of that load on the spar, twisting the fuse and bending the VS spars to near instant failure. If so, I then might imagine the VS leveraging against the rudder and separating it below the center pivot. The report stated it pulled out the TE rivets. There may have been some flapping there, as the rudder CW separated early and went ballistic, landing near the main body of the plane. (some confusion about exactly what induced CW separation if the remainder of the upper rudder came down with the VS.)

I believe the report did state that the remaining rudder showed impact with the elevators.
 
Getting it corrected is one thing. Finding out why it's wrong is another. If the examiner looked at the wreckage, thought he was looking at aileron cables, and proceeded on that assumption, then one might question his competency at evaluating the rest of the incident.

Mr Nixon did say there were others that entered that part of the report. He sounded a pleased and maybe a little surprised that it was being closely read.

Regardless, you make a good point about the thoroughness and quality of the process.
 
wow

... and maybe a little surprised that it was being closely read. ...
Gobsmacked - this is probably the first time in my life I've used this word, and I think it's perfectly appropriate here.

BillL, I have to admire your "out of the box thinking" to call this guy up to discuss it. It seems like such an obvious thing to do, but I doubt I would have thought of doing that in 100 years. I guess you can pass on to him the fact that 1000s of people read these reports meticulously, both trying to learn how to avoid ending up in one of these reports, and if it does happen, how to not look like a knucklehead.
 
There are photos available, in the Document Management System.

I assume everyone has access to this link:

https://dms.ntsb.gov/pubdms/search/...cb1ebf74a-CEB0FFB9-C5A8-2749-B85E239E3BE61D8C

Or as an embedded link, click here.

I haven't studied these photos intensely. There are three in Section 14, "Onsite Pictures," and there is one photo of interest in Section 10, "Airframe and Engine Examination Report." By hitting the enlarge button, a lot more detail can be seen. I wish we had more photos to view. I'm quite confident they made a lot more photos. I'd like to see the photo of that splayed "aileron cable" they described.

P.S. I found more photos in Section 2, "Structures Group Chairman's Factual Report - Appendix A - Figures."

I'd rather not speculate, but there is a lot to be learned by studying these photos.
 
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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.

It's my understanding that, as a point of law, NTSB reports are not admissible in court. The government has exempted itself from that can of worms.
 
It's my understanding that, as a point of law, NTSB reports are not admissible in court. The government has exempted itself from that can of worms.

The conclusions of the probable cause are not admissible. Factual findings of physical evidence are. Considering the enormous implications in a court of law of these error in the fact-finding, this is a serious issue for the NTSB. This is negligence at best, IMHO.
 
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It's my understanding that, as a point of law, NTSB reports are not admissible in court. The government has exempted itself from that can of worms.

That would be news to me; there's a very famous Supreme Court case (Beech Aircraft Corporation v. Rainey, 488 U.S. 153 (1988)) directly on point about the admissibility of accident reports. Granted, that was a Navy investigation, not an NTSB investigation, but the case was about the admissibility of public records. From Wikipedia:
Beech Aircraft Corporation v. Rainey, 488 U.S. 153 (1988), was a United States Supreme Court case that addressed a longstanding conflict among the Federal Courts of Appeals over whether Federal Rule of Evidence 803(8)(C), which provides an exception to the hearsay rule for public investigatory reports containing "factual findings," extends to conclusions and opinions contained in such reports. The court also considered whether the trial court abused its discretion in refusing to admit, on cross-examination, testimony intended to provide a more complete picture of a document about which the witness had testified on direct.
The Court held, generally, that the JAG report was fully admissible, not just as to factual findings but also as to conclusions and opinions, to wit:
The Court reversed the judgment of the Court of Appeals on the Rule 803(8)(C) issue. In the Court's holding, the Court stated: "We hold, therefore, that portions of investigatory reports otherwise admissible under Rule 803(8)(C) are not inadmissible merely because they state a conclusion or opinion. As long as the conclusion is based on a factual investigation and satisfies the Rule's trustworthiness requirement, it should be admissible along with other portions of the report." The Court also agreed with the Court of Appeals that the District Court erred, stating "We agree with the unanimous holding of the Court of Appeals en banc that the District Court erred in refusing to permit Rainey to present a more complete picture of what he had written to Morgan. We have no doubt that the jury was given a distorted and prejudicial impression of Rainey's letter."
If the NTSB is different, I'd love to know why; if nothing else, the report--and its change history--ought to be admissible to impeach the credibility of the witness (the investigator who prepared the report, and possibly other investigators as well).

Incidentally, I think Rainey is ripe for re-examination, albeit for slightly different reasons.

The conclusions of the probable cause are not admissible. Factual findings of physical evidence are. Considering the enormous implications in a court of law of these error in the fact-finding, this is a serious issue for the NTSB. This is negligence at best, IMHO.

Again, please cite as to why they're not admissible if you can; that is directly contrary to Rainey, and I'd love to know more.
 
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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.
 
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!
 
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)?


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.
 
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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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.
 
Not sure if you all know you can look up the backing data.

The "structures groups chrirman's reports" go into 4 pages of details. One item popped up

"All the fractures examined had a dull, grainy appearance consistent with overstress separation. There was no evidence of progressive or pre-exiting fracture on any of the parts examined. Many of the rivets examined appeared to be not sufficiently driven"

There were many comments about how H stab skins had peeled open. If this was inflight or impact don't know.

The figure of debris field is telling... H Stab south end of debris field, left wing tip and out board wing with canopy middle, north end the main wreckage... All of this from south to north is over a fairly large area. No doubt the H stab came apart first.

The report was corrected (removed control cable splayed) with errata amendment that reads:

"Control continuity was established from the control stick in the cockpit to both elevators and
the right aileron. The left aileron control rod aft rod end was fractured from the control
rod. The rod end remained attached to the aileron control horn at the inboard aileron hinge.
Control continuity was established from the control stick in the cockpit to the left aileron
bell crank and aft to the fracture point on the left aileron control rod. The rudder cables
were jammed somewhere in the fuselage so continuity could not be established but the
cables remained attached at the rudder and the pedals. "
 
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