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  #21  
Old 11-17-2018, 08:36 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Small detail... passenger listed as Airplane Rating(s): Single-engine Land with (Estimated) 3.2 hours (Total, all aircraft)

NTSB needs a proofreader?
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  #22  
Old 11-17-2018, 08:49 AM
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Regardless of the errors in the report and probably some false assumptions, the accident wasn't caused by an airframe design failure, pilot error, recklessness, or other cause that anyone could control. I look at these reports to try to educate myself and avoid trouble. There is little to learn here. It was a very odd and rare event that led to an unavoidable and tragic accident.
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  #23  
Old 11-17-2018, 04:06 PM
Canadian_JOY Canadian_JOY is offline
 
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Quote:
Originally Posted by Piper J3 View Post
NTSB needs a proofreader?
I was asked to proof-read a couple of TSB reports prior to them being published. The person asking has a masters in translation and, on a personal level, a perfectionist. Even with that person's considerable editorial skill applied I still managed to bleed a fair bit of red ink on the documents. Getting a document of this nature right takes a lot of effort, effort that's typically not going to be invested by an individual who is tasked with applying greater effort to the act of completing the actual accident investigation.
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  #24  
Old 11-17-2018, 04:35 PM
BillL BillL is offline
 
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All the supporting documents seem to be correct, it's just the top level summary.

I think the materials lab report has the best attempt at the root cause. There is a lot of information in this(these) report(s) taking a lot of study to understand just exactly what is being said.

Not much discussion here about what happened beyond the multiple bird impacts. It appears in Fig 17 in the materials lab document that the LE of the left HS was impacted and deformed by the strike. There are no immediately visible causes for the separation of the VS or the (now familiar) failure mode of the rudder. There is a small deformation on the RS of the lower LE of the VS, but could be the result of ground impact on that tip.

For structural guys, it is possible for the mass of a pigeon with an additional velocity of 88 FPS to penetrate/deform the HS and precipitate failure?

While it is highly probable that the bird strikes are the root cause, the haunting (and familiar) image of the failed rudder awoke me at 3AM.
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  #25  
Old 11-17-2018, 06:15 PM
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Quote:
Originally Posted by BillL View Post
While it is highly probable that the bird strikes are the root cause, the haunting (and familiar) image of the failed rudder awoke me at 3AM.
Your hinting it could have been a rudder failure?
To my knowledge there have been two or three tail departures over 10k plus aircraft. All attributed to gross over speed of the airplane.

If I was so worried about the rudder design of the RV series that I lost sleep over it, I wouldn't own an RV.

Perhaps I am just not understanding what your getting at here Bill.
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  #26  
Old 11-17-2018, 06:19 PM
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Default Maybe a defected bird unzipped it

Maybe the bird deflected off the horizontal or vertical, hit the rudder hard enough to unzip it, then it was all history at that point. What ever the official reason, reading a report of finding another unzipped rudder at a crash site is what wakes me up at 3am. Good thing mine is hanging on the hangar wall where it is safe from birds and fludder.
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  #27  
Old 11-17-2018, 06:20 PM
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the omission of the canopy photos or discussion of the canopy is suspect. the canopy was found with the rudder. seems to me the canopy became loose somehow and took the tail off. I don't know how that could happen but I don't own a slider.
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  #28  
Old 11-17-2018, 06:53 PM
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Quote:
Originally Posted by Steve Melton View Post
the omission of the canopy photos or discussion of the canopy is suspect. the canopy was found with the rudder. seems to me the canopy became loose somehow and took the tail off. I don't know how that could happen but I don't own a slider.
Or it could be as simple as a bird strike penetrating the canopy, with pilot incapacitation, followed by an overspeed event.
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  #29  
Old 11-17-2018, 09:43 PM
BillL BillL is offline
 
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Quote:
Originally Posted by JonJay View Post
Your hinting it could have been a rudder failure?
To my knowledge there have been two or three tail departures over 10k plus aircraft. All attributed to gross over speed of the airplane.

If I was so worried about the rudder design of the RV series that I lost sleep over it, I wouldn't own an RV.

Perhaps I am just not understanding what your getting at here Bill.
Not hinting at this as a root cause, Jon. But to be clear, there have been 4 structural failures, all 7's, so 4 out of 1600. They are C-GNDY - overspeed, N174BK- overspeed, N307AB - turbulence, and an unfinished report for the NZ one in Jan-2018.

Regardless, the rudders all were the standard 9/7 tall rudder and seem to fail in the three pieces. This is not implying the rudder is the root cause here as it clearly is not, but it did (fact) become part of the cascade of events. I can only assume that operating the 7 within the design envelope will not result in any failures and, therefore, shall continue to own and fly my 7. Flight data is recorded for every flight.
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and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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  #30  
Old 11-17-2018, 09:51 PM
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Thanks Bill. Fair enough.
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