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Help researching 1961 Electra crash

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Help researching 1961 Electra crash

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Old 29th Nov 2017, 15:48
  #181 (permalink)  
 
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megan: "From information provided I calculate the point of wing tip contact is some 14 feet below the top of the embankment. The impact scar from the wing is as near vertical as can be estimated (ignoring dihedral), and the scar across the railway lines is vertically above the wing tip point of contact ie the angle of bank was pretty much 90, and backs up the CAB statement, “about 85”.

Haven't seen the wing impact evidence on the embankment, and apologize for being late to the discussion. If the impact scar was caused by a wing, the angle would depend on the velocity of the wing tangential to the obstruction, no? An embankment has a grade, what was it? A wing has dihedral, and a heading, plus a velocity of its own. Those are a lot of factors to be considered to arrive at a conclusion "the wing had a ninety degree aspect at impact".

I may be way too behind to merit comment here, but my initial queries would include:

Did the pilots have aileron command? Was the Rudder operating as designed? Were the pilots trying to gain directional control by differential thrust? If there was a severe vibration before impact, was its origin determined? Collecting serial numbers of each propellor blade, was it possible to recreate the path of each?

Having experienced Whirl Mode on an early Electra as pax, abeam the wing, I can testify to the alarming behavior of wing/power plant. It would have been an extremely difficult recovery in normal flight, let alone one hobbled by inop ailerons. What about walk around, controls checks? Depending on the orientation of the prop strikes, would it be possible to determine if the power plants were even still attached prior to impact? Had one separated prior to impact would certainly explain inversion of the airframe.
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Old 30th Nov 2017, 16:18
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Hi Megan,

Incontrovertible. No such thing, sorry. Maybe in 101.

From the aerial, I can make a supposition subject to evidence re the embankment scar.

1. If the wingtip, there is no possibility propellor ruts would be symmetrical. (allowing a GS calc...)

2. If the wingtip, there is not enough mass to disrupt the rails to such an extent.

3. If the wingtip, the width of the scar would be much narrower, the scar is too wide.

4. Supposition. Number four experienced catastrophic mount failure, was hanging low, and tore up the embankment prior to wing contact.

From the audio: "have you...." (Feathered four?) "we cannot recover the right roll"

5. How were the aileron cables and boost reconstructed to determine a "fatal flaw"

6. What was the argument that supported two months of aileron duty as serviceable until the fatal launch?

7. Could Lockheed have survived another aircraft loss due to engine mount flaws?

8. Clear your mind, look closely at the scar, and give your consciousness respite from "incontrovertible".....

Best regards,

Concours

Craig: "The plane's stall angle in a bank was about 63 degrees that day, by the way. They were descending not because they were in fact stalled, but because they were feeling the shaking in the controls and knew a stall was near, and they were fighting to keep the speed up by keeping the nose down. Rolling left, close to recovery, they ran out of air."

The aircraft was crossing the ground at 160 knots. What was the wind? If you dismiss the radical roll angle, you should question your consideration of Stall? If so, we need a source for "shaking in the controls...." "Rolling Left, close to recovery...." Does this contradict the CVR "cannot recover the right roll...." Final words, "have you...." (?) this interrogatory suggests a belief in recovery, however remote. My best guess given the controversy here as to roll angle might be "have you feathered four?"

BTW. If Propellor hit first, and included the powerplant (it would), it becomes clear the wing tip may have risen immediately. Why? Once integrity of the spar is lost, all the lift being generated by the wing outboard of #4 instantly lifts the outer wing, clear of the embankment...

Last edited by Concours77; 30th Nov 2017 at 17:17.
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Old 30th Nov 2017, 20:05
  #183 (permalink)  
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Originally Posted by Concours77 View Post
Craig: "The plane's stall angle in a bank was about 63 degrees that day, by the way. They were descending not because they were in fact stalled, but because they were feeling the shaking in the controls and knew a stall was near, and they were fighting to keep the speed up by keeping the nose down. Rolling left, close to recovery, they ran out of air."

The aircraft was crossing the ground at 160 knots. What was the wind? If you dismiss the radical roll angle, you should question your consideration of Stall? If so, we need a source for "shaking in the controls...." "Rolling Left, close to recovery...." Does this contradict the CVR "cannot recover the right roll...." Final words, "have you...." (?) this interrogatory suggests a belief in recovery, however remote. My best guess given the controversy here as to roll angle might be "have you feathered four?"
Wind was negligible - 6mph out of the south, so crossways to the flight path. The mental model I've been developing is that the plane was in a fairly high bank which they were getting under control in the last few seconds. By no means do I dismiss the radical angle; I just think they weren't still at that angle when they hit. My somewhat long explanation for this is at

http://www.pprune.org/accidents-clos...ml#post9539907

I will be expanding on this premise in the next release. I think the physics are a little like an engine coming over top dead center. If there's pressure in the cylinder it moves very slowly until it gets a few degrees from TDC and then it can snap very fast. Same thing with a rock rolling off the flattish top of a hill - once it hits the slope it goes fast. I suspect the plane was sort of balanced in a high bank until the rudder started to bite, but once it bit the plane was rolling left fast. The flatter the plane got, the faster it would flatten. 35 degrees was totally flyable, after all, and not even close to a stall at that point.

My video attempting to recreate this is at https://www.youtube.com/watch?v=D4_b1ekxKkY

With the 93,000 gross weight the stalling speed in that temperature and altitude was about 110 knots. At 63 degrees the stall speed hits 160 knots. There is no stick shaker; the Electra crew sensed turbulence on the elevators as the wing airflow starts to separate. So they would have felt a mushy response and shaking, and they were guiding down to try to keep the speed up.

There was no CVR. The voices were captured on the tower radio recording.
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Old 30th Nov 2017, 21:26
  #184 (permalink)  
 
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Whatever the flight path, it is secondary to momentum. Mass continues in its path unless acted upon or hitting an obstacle. The "acted upon" (command) seems to be without sufficient authority to alter the flight path, but in this case, the momentum seems to have been consistent with obstacle, or impact.

The recent example of low speed, near Stall grief is Asiana at SFO. It is remarkable how quickly an airframe can respond, but remember size and mass are deceptively at odds in large aircraft.

The triple seven rotated immediately in the horizontal when the right main gear hit rocks at threshold. This acceleration of the aircraft caused a violent wing over, and these folks were immeasurably luckier than those on your Electra.

Another exemplar might be FedEx at Norita. The MD11 oscillated emphatically until the right wing spar collapsed, and the aircraft rotated violently with the (resultant) massive asymmetric increase in AoA.

Prolly no yaw damper on the Electra? I certainly agree most crew would be actively on the Rudder to control heading and roll.

So you mesh pre Stall buffet with control yoke oscillation? At ninety degrees roll, there is no lift at all, save that reserved for heading! Rudder becomes elevator at knife edge. I don't see that, there is far too much forward travel. Dropping at that rate I would expect a smoking hole, not so much linear advance?

BTW, thank you for such a measured and intelligent discussion.
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Old 30th Nov 2017, 21:47
  #185 (permalink)  
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Originally Posted by Concours77 View Post
At ninety degrees roll, there is no lift at all, save that reserved for heading! Rudder becomes elevator at knife edge. I don't see that, there is far too much forward travel. Dropping at that rate I would expect a smoking hole, not so much linear advance?
That's my opinion, but I'm not a pilot. That's why you're here!

The Electra can't knife-edge fly until it gets to about 250 kts. My simulator video is at https://www.youtube.com/watch?v=2JiGSJ5xPQg So at 90 degrees and 160-ish kts we're talking about pure ballistics, and it would drop like a rock. I graphed that on page 24. But Lockheed measured a 5 degree slope from the power lines to the embankment. That sounds like a landing with no flare.
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Old 30th Nov 2017, 23:04
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Flight 706 in knife edge? The eyewitness claims he saw a wing fall out of the clouds, then seconds later, a fuselage with wing attached?

A five degree glide slope is survivable. And impossible with the reported roll angle. At a ground speed of close to 200 mph (I find that hard to believe), we are talking pure fantasy.

If 90 degrees roll angle and Stalled, she has also already spun, and wants to get on her back. That is completely incompatible with the debris trail. IMO.

Cartwheel? Certainly possible, but I am missing some important evidence.
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Old 1st Dec 2017, 07:57
  #187 (permalink)  
 
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Um, not sure if these will help in identifying the debris, but I came across PDFs of a few Lockheed L-188 Electra Field Service Digests (from 1958, '59 and '61), containing detailed descriptions, drawings, and photos of airframe, flight control system, power plant, etc. The originating Brazilian site is ad-infested and somewhat sporadic, so I've copied the files to:

https://www.dropbox.com/sh/7zhhl0jxu...tjxxnEeWa?dl=0

for easy download.

c
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Old 1st Dec 2017, 11:13
  #188 (permalink)  
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Thanks cordwainer, but none of them will open, Acrobat says they're invalid or broken. What's the site? I'm willing to wade through the ads.
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Old 1st Dec 2017, 12:07
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The documents open just fine using an iPad.
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Old 1st Dec 2017, 13:32
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Opened fine in Google Chrome too.
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Old 1st Dec 2017, 13:58
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I see what happened. My initial downloads were interrupted, so the files were unreadable. Downloaded again, got everything fine. Unfortunately, it turns out to be three I already had! Thanks anyway cordwainer for your work, I appreciate it.
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Old 2nd Dec 2017, 15:04
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Craig, If you have the time, I'd like to ask some questions.

1. Your video. During T/O roll, Did you intend to show the aircraft drifting off centerline to the right? If asymmetrical thrust, would that explain? Aileron would not have caused this drift, IMO.

2. Never more than 300 feet AGL, why did the aircraft initiate a turn so soon? If related to the aileron issue, wouldn't the crew have input left Rudder immediately? If in an unrecoverable right bank, and the immediate turn has to do with this, I would expect an immediate mayday? If a thrust issue, the pilots may have been satisfied trying to sort it before making a call?

3. Is there additional discussion, either in the report or elsewhere about "there was a change in the sound of the engines?"

4. Could you direct me to any data relative to the impact on the railway berm? Was there exhaustive inspection of the area between power line sever and wing tip contact on the gravel ballast? Were carbon tracks found anywhere on the debris material indicating high voltage contact?

5. Is there professional analysis of the presence of internal engine bay material so close to initial impact?
It would seem unprofessional to leave out identification of the telltale piece we think might be motor mount/vibration snubber?

6. Wouldn't you consider the collision with power lines to be "initial point of impact"?

7. If the a/c was incontrovertibly in ninety degree bank, and falling rapidly, why would the debris field not be closer to the tracks, but displaced further forward? This would tend to put in jeopardy the "ninety degree bank" conclusion?

Though these questions may have been answered in the report, my purpose is not to correct or defend a flawed report, but to seek the truth.

Last edited by Concours77; 2nd Dec 2017 at 15:23. Reason: Seeking answers
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Old 2nd Dec 2017, 19:31
  #193 (permalink)  
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Concours77,

1. The slight drift is an artifact of the way it's flown, no meaning intended. The simulator does not fly the aircraft in a goal-seeking process, guiding up to reach a desired altitude, banking right to a desired bank. The simulator is under the control of a scripting program I wrote which simply replays control inputs that were recorded from a prior run. I wrote an editing interface, and I tweak the script until I get the results I want. The simulator has a built-in randomizer to make the world seem more realistic, so each flight has tiny variations. It's the electronic equivalent of launching paper airplanes. The result is like a shotgun - a closely grouped set of results, no two quite the same.

2. The turn was planned that way. They had no idea they had a problem until they tried to flatten the bank. By the time they saw there was a problem, they were in a bank somewhere over 20 degrees. This was I think a fatal circumstance not mentioned as a contributing factor in the reports. If the aileron had become unresponsive in level flight, they would have been fine.

3. There were several comments in newspaper reports. At the time this was a subject of intense discussion. It is baffling to me that it was never addressed in the reports, considering the contemporary discussion. The reports say the engines were turning and delivering power, but there's no confidence that it was full power. Still, the speed was about right for that point in the takeoff, and it was the excessive bank that made the speed critically low. Equally interesting is how low they were. The reports say they were slightly low, but they were about half the normal altitude, which is also never really addressed.

4 and 5. I have no other information on the berm or debris. This is why I keep looking for investigation documents. My sister has some experience with document retention policies, and she's sure the investigation documents are still around. But no one gains a thing by releasing them to me, or acknowledging to me that they exist. There's always the possibility of liability issues. A reopening of the investigation would shake them loose, of course.

6. Don't see that the label matters. It's possible the power lines interrupted what may have been an incipient recovery. None of the power line pictures show indicator globes between the poles, planes weren't supposed to be there, and it's probably a safe bet that the crew never saw them.

7. The debris should have been closer and the right wing should have been obliterated. Compare to the Argentine crash on page 63 and watch the video linked there. I don't think a near-vertical bank is credible for several reasons.

I'm currently working on some CGI software to help visualize all this.
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Old 2nd Dec 2017, 20:30
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I would have wanted more attention paid to the powerlines in the day. If the poles are at sixty feet, how high were the lines? (Sag). This is important, it bears directly on the fligh path and impact orientation....

For obvious reasons, a departure turn can't be initiated until deemed safe, or by rule (noise abatement). Was there "maintain Runway heading to "x feet" then make right turn to _____?" From the video, the turn was early, very. Even if well known to the crew, ATC would be required to command the proper procedure. I would have been alerted to a problem before the non responsive left inputs, due to lack of climb rate? Unfamiliar with Electra, but wouldn't right rudder have accompanied right aileron? Any tendency to skid would have been noticed immediately, and the unfamiliar (Un-co-ordinated inputs) controls would also have been an alert (sluggish response in roll "correction?")

From the photographic evidence, the displaced second impact argues strongly against extreme bank angle. Simply balancing the (reported) ballistic calcs would be fatal to the ninety degree value postulate, IMO.

What persuades you to suggest pilot input Nose Down? If no extreme roll, no pre Stall buffet? Hence no need for nose down. I am intrigued by the "shaking control column". How do we know this?

I am aware that if the aircraft did not experience extreme right bank, and the impact is the tip of the right wing, we are obligated to entertain a wing already broken?
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Old 2nd Dec 2017, 20:47
  #195 (permalink)  
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The tower had already approved what they called a "toll road departure" which is apparently local jargon for an early right turn. Probably because it lines up with Irving Park Drive being the tollroad in question, but that's a pure guess. So they were turning as permitted.

Right rudder would have been automatic, due to an interlock between the rudder and control yoke. It's spring-loaded so it can be overcome. I'm told it's common to not touch the pedals on many flights/planes because this interlock gives the right degree of rudder for turns. There was no hint of unresponsive left input until they actually tried a left input when turned far enough right, and then nothing happened. At that point they had about 22 seconds left in the air.

I think they were experiencing pre-stall buffet and that's why the nose was down (as witnesses reported). The stall angle at 160-ish knots was about 63 degrees and they were close to 60, so (speaking as a non-pilot) my understanding is they would have felt the shaking. What I look for here is feedback from pilots to tell me if I'm on the right track.

They were absolutely in an extreme bank, in my view, and were rapidly recovering from that when they ran out of altitude. When they hit the embankment at about 35 degrees, that was a highly transient state.
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Old 2nd Dec 2017, 21:38
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What I meant in the rudder/aileron coordination would be as the roll kept increasing, the rudder would not have kept up, since the ailerons were locked in a certain position? As the roll kept increasing, the aileron setting would not have matched with yoke position, and the uncoordinated controls would have felt "skid dish" on the cheeks. IOW, the airplane would have signaled an aileron problem before they tried to recover. Also, they would have selected a specific roll angle, the aircraft roll would need to be "stopped" at a certain value, and held in neutral aileron to acquire a smooth and consistent turn rate. I don't buy that the pilots were unaware of the problem prior to excessive roll, they would have known something was wrong when they selected an angle to sustain, tried to stop roll, and the bank kept increasing....follow? But even before that, the skid would have alarmed them.

If unresponsive in roll, the Captain would have instantly retarded the thrust levers on the two port side power plants. There would have been a very powerful turn to the left, and any rudder selected by the Commander would have easily overpowered the "linked springloaded" roll design....problem solved.

He May have also selected Nose Down, but the immediate roll left would eliminate the pre stall buffet?
At one hundred feet, Nose Down would be a last resort?

Unless, the starboard power was compromised in some way, by engine failure. If power (thrust) on the right side was compromised, any turn to the right is trouble.

Last edited by Concours77; 2nd Dec 2017 at 22:04.
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Old 4th Dec 2017, 02:31
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As always, this may be data you've already found, but just in case not:
Though NTSB does not have CAB archives prior to about 1965, there is a section of CAB Records in the National Archives at College Park, MD, details at
https://www.archives.gov/research/gu...roups/197.html
197.3.5 Records of the Office of the General Counsel references "aircraft accident investigations, 1952-64", as well as some contemporaneous records related to liability and litigation which, though a longer shot, might include pertinent material.

By the way, concerning the existence of retained records, I noticed you wrote above in one post,
"...no one gains a thing by releasing them to me, or acknowledging to me that they exist. There's always the possibility of liability issues. A reopening of the investigation would shake them loose, of course."
As someone whose work involves quite a lot of research, I think you are right to be cynical...but I think you're cynical about the wrong thing.

Realistically, none of these agencies or companies has anything to lose by releasing archived records from a closed, 55-year-old, well-publicized public investigation. But I began my research from a point of cynicism as to whether some of the people you contacted for information really knew what they were talking about. Or if they pointed you in another direction just because they didn't want to be bothered. Both are a lot more likely than them trying to hide something or stonewall you.

To be fair, I'm sure the intentions of most were good, and they genuinely believed they were giving you accurate information. But as you've seen, some of those records exist in public archives despite assertions to the contrary.

Loss of institutional knowledge is endemic, especially after half a century. Most likely there's just no one left at the agencies/companies or their successors who has first-hand knowledge of where old records ended up. And there's more stuff out there no doubt in collections of personal papers and correspondence of the various executives and investigators. The Chicago Tribune now sells old photos from its archives, so you may be able to get a clear print of the track debris photo...albeit not for free. Lockheed's website contains references to all documents from California being moved to their warehouses in Marietta, GA when the CA facilities closed. Someone must know what's in those warehouses, given the number of scholars, researchers, and scientists still writing about Lockheed's role in aviation history, and those interested in every aspect of the various Electra versions. Etc., etc., etc.

In other words, your sister is right. Don't give up. We have not yet begun to search :-)

Last edited by cordwainer; 4th Dec 2017 at 04:37. Reason: original post far too long and silly
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Old 4th Dec 2017, 05:36
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These 3 files together may clarify the early right turn and the meaning of "toll road departure":

https://www.dropbox.com/s/gkc2m29h0k...ption.jpg?dl=0
https://www.dropbox.com/s/724jm9z8mg...chart.jpg?dl=0
https://www.dropbox.com/s/uurh7m9oat...OHare.jpg?dl=0

The "departure routing description" is from an April 1962 O'Hare master plan analysis, based on operations information from "...late Fall or early Winter of 1961."

Note the paragraph beginning, "Departures to the south...", particularly the last sentence: "Formerly, this routing was circuitous--aircraft proceeded via Victor 172, Victor 429, and Victor 38 to Peotone."

If I'm reading the chart correctly, in September 1961 the "circuitous" routing might have been the reason for initiating the right hand turn - toward V172 in the direction of V429, and thus toward the Northwest Tollway which V172 roughly parallels. Irving Park Rd/Route 19 is not a toll road, the Tri-State Tollway is in the other direction, and the newer "direct southerly routing through the Midway vector area..." surely wouldn't require first turning that much to the right?

Could the circuitous routing have been changed partly as a result of the accident, considering the investigation would still have been in its early stages? I.e., was the early turn itself, at some point, implicated as a causal factor?

As always, hesitant to interpret or make suppositions, as a non-pilot, so please feel free to swat me if all this is irrelevant.

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Old 4th Dec 2017, 11:16
  #199 (permalink)  
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Thank you for the routing information. I'd wondered about it, but never heard that the turn itself was thought to be a contributing factor.

The National Archives did a search of the CAB documents. They said all they had was the final report.

I've been working on a graphic/animation tool to help illustrate and visualize. I installed an Electra and am exploring how to use it. Right now it's bare metal, still working on getting the NWA paint on it. I intend to replace some of my pretty primitive drawings with better ones.

My initial project was to pose it in proper scale on the picture of the RR tracks. Boy, now that I see it in scale it's real hard to imagine anything more substantial than the wingtip hitting. The software has not yet output an image. When I get that working I'll post it.
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Old 4th Dec 2017, 11:19
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Concours - I understand what you're saying. This is why I want to hear from pilots. The interlock between the ailerons and rudder doesn't actually link them directly, it's a linkage at the flight station. So if the ailerons deflection doesn't match the control inputs, the rudder won't hear about that, so to speak.
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