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lwhitlow
Joined: 15 Jan 2006
Posts: 76
Location: Valparaiso Indiana
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 Posted: Mon Dec 07, 2009 8:49 pm Post subject: Agnos AR NTSB Pics are up |
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Agnos AR NTSB Pics are up
I saw them posted over on the zenith.aero site here
http://www.zenith.aero/forum/topics/ntsb-photos-from-most-recent
My question after viewing them is still the same as it was after seeing the Yuba City pictures
What failed first??
The pics show the compression buckling in the rear spar at RR7 ( the rib that mounts the bell crank) and in other places inboard But the notes also indicate that the cables, bell crank, aileron push rod and aileron bracket were ripped out through the wing as the wing left the airframe and all remained attached to the fuselage. Could some of the noted damage have come from this stuff getting pulled through the wing?? I mean that bell crank is not gonna fit through the holes in the ribs and if it comes out that way could it cause the bends in the rear spar?? Pics of the interior of that wing would help.
The score marks on the flap are also interesting. Enough upward force was put on the flap push it up past the stop so its upper leading edge made contact with the rivet bottoms in the rear spar. Or did the wing rear spar move down, with the flap held in place by the control arm thus causing the scars Again a pic of the rear spar doubler / mounting hole and the rear spar attach bracket would answer the question
I would really like to see the failure mode of the main spar to center spar and the rear spar to rear attach
You would think in this day and age with digital cameras what they are, there would be hundreds of pictures. I mean its only electrons
Larry Whitlow
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paulrod36(at)msn.com
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| Posted: Tue Dec 08, 2009 10:44 pm Post subject: Agnos AR NTSB Pics are up |
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<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Sorry to be so blunt, but these pictures show diddly., so I've got a few questions:
Why are there no pictures of the wing spar attach points? Why are there no pictures of the wing spar carry-throughs? Who took these pictures? And who selected these?
Let's review what happened here. The wings separated in flight, thus causing the crash. Buckling of the rear spars somewhere outboard would have made the plane uncontrollable, but it would not likely have come apart until impact. That's not what we see here. The wings are elsewhere, having come off and been stripped of their aileron cables and bell cranks in the process. Not surprising; that's a 900-pound or so tensile cable pulling out of a 200 or so pound tensile wing rib. Of course it will tear a hole where the pushrod was, and MAYBE cause a compression failure in the rear spar top or bottom, but the compression failure could have as easily come from impact, AFTER separation. Either way, the compression failures had to occur AFTER wing separation. You wouldn't get compression failures like that unless the main spar bent backwards. We don't have a view of the spar. Back to the questions: How did the wings separate? Without the evidence provided by pictures (and a few microscopic close-ups would also have been helpful) we don't know if the wings moved longitudinally to failure, or vertically. Did they fail upwards or downwards? Did anybody check the fuselage side skins for the gouges which must have been made at the time of failure? Which component, the main or rear spar, failed first? Are the broken ends torn, sheared, or bent to failure? Do the broken ends show oxidation, or pitting, as might be seen in a substandard material, or old fatigue crack? How much twist is there at the failure point? The rivet marks on the flaps don't mean much. Once the actuator arm is separated, the flap can bang back and forth in the turbulent airstream of the falling wing, or its inertia can cause those marks if the wing hits the ground leading edge first, or inverted, or even flaps-first. Maybe the crash investigator addressed these questions during his examination of the wreckage, but if he did, we should have access to those answers.
The pictures we see apparently were taken from 14:51 to 16:26. In an hour and 35 minutes, he had to have taken more than 11 pictures.
Anybody feels like flaming, go right ahead. But we still don't know any more now than earlier.
Paul R
Waiting for the kit.
[quote] ---
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Gig Giacona
Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA
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| Posted: Wed Dec 09, 2009 6:07 am Post subject: Re: Agnos AR NTSB Pics are up |
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Those pictures tell nothing. Every bit of that damage could have happened on impact. Where the wing connects to the fuselage is what we need to see.
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W.R. "Gig" Giacona
601XL Under Construction
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zenithlist(at)yahoo.com
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| Posted: Wed Dec 09, 2009 6:44 am Post subject: Agnos AR NTSB Pics are up |
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Those pictures show quite a bit of info and I concur that more pictures showing the junction points between the wings & fuselage would be better. However, I would place a good bet that once the rear spars buckled such that the plane became uncontrollable, the wings would quickly depart thereafter.
From: "paulrod36(at)msn.com" <paulrod36(at)msn.com>
To: zenith-list(at)matronics.com
Sent: Tue, December 8, 2009 10:42:54 PM
Subject: Re: Agnos AR NTSB Pics are up
Sorry to be so blunt, but these pictures show diddly., so I've got a few questions:
Why are there no pictures of the wing spar attach points? Why are there no pictures of the wing spar carry-throughs? Who took these pictures? And who selected these?
Let's review what happened here. The wings separated in flight, thus causing the crash. Buckling of the rear spars somewhere outboard would have made the plane uncontrollable, but it would not likely have come apart until impact. That's not what we see here. The wings are elsewhere, having come off and been stripped of their aileron cables and bell cranks in the process. Not surprising; that's a 900-pound or so tensile cable pulling out of a 200 or so pound tensile wing rib. Of course it will tear a hole where the pushrod was, and MAYBE cause a compression failure in the rear spar top or bottom, but the compression failure could have as easily come from impact, AFTER separation. Either way, the compression failures had to occur AFTER wing separation. You wouldn't get compression failures like that unless the main spar bent backwards. We don't have a view of the spar. Back to the questions: How did the wings separate? Without the evidence provided by pictures (and a few microscopic close-ups would also have been helpful) we don't know if the wings moved longitudinally to failure, or vertically. Did they fail upwards or downwards? Did anybody check the fuselage side skins for the gouges which must have been made at the time of failure? Which component, the main or rear spar, failed first? Are the broken ends torn, sheared, or bent to failure? Do the broken ends show oxidation, or pitting, as might be seen in a substandard material, or old fatigue crack? How much twist is there at the failure point? The rivet marks on the flaps don't mean much. Once the actuator arm is separated, the flap can bang back and forth in the turbulent airstream of the falling wing, or its inertia can cause those marks if the wing hits the ground leading edge first, or inverted, or even flaps-first. Maybe the crash investigator addressed these questions during his examination of the wreckage, but if he did, we should have access to those answers.
The pictures we see apparently were taken from 14:51 to 16:26. In an hour and 35 minutes, he had to have taken more than 11 pictures.
Anybody feels like flaming, go right ahead. But we still don't know any more now than earlier.
Paul R
Waiting for the kit.
[quote] ---
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paulrod36(at)msn.com
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| Posted: Thu Dec 10, 2009 11:04 am Post subject: Agnos AR NTSB Pics are up |
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<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Sorry, I must disagree. The outboard buckling of the rear spar is too far away from the point of failure (attach points) Once the rear spar started to buckle, any stress at the attach point was alleviated. IF the plane were uncontrollable, it wouldn't have been able to exceed Vne. The thrust line largely determines the vector of speed to Vne, and, even if it were over Vne, what we know about moment arms, etc., would have had the attach point fail first, and the forces at the mid point of the wing would have immediately ceased. I'm sticking with impact damage.
Paul R
[quote] ---
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