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Help researching 1961 Electra crash

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Help researching 1961 Electra crash

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Old 5th Jan 2018, 16:52
  #321 (permalink)  
 
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An example of CAB’s “certified by signature” logic:

Page twelve para three: “The pilot’s cable disconnected”.....

Page thirteen, para three: “The left wing down cable separated”..... (co-pilot’s cable)
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Old 5th Jan 2018, 17:11
  #322 (permalink)  
 
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Originally Posted by BRDuBois View Post
Don't believe I mentioned a voice recorder. What page are you speaking of?
Narrative 38, 4th paragraph down starts "The cockpit voice recorder had no recoverable data."

Probably just a slip, but I wanted other readers to be clear on the recorder type.
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Old 5th Jan 2018, 18:05
  #323 (permalink)  
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Ah, you're looking at the Cockpit Resources chapter that isn't part of the document yet.

Thanks for pointing it out. That was a dumb thing for me to say.
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Old 6th Jan 2018, 00:16
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Concours77

"You must know that the Captain was busy trying to recover left roll. He said so. Left roll was available, I have demonstrated that."

Clearly an aileron roll to the left, or even a return to neutral, was not possible otherwise the aircraft would not have maintained a steadily increasing bank angle and right turn.

While I appreciate that some people have issues with the phraseology and terms used in the accident report and that there are discrepancies in the presentation of information from many different sources in the summary, the report stands as an accurate reconstruction of events. There can be few past events that can withstand such concentrated scrutiny at this distance in time and the original results still stand up in the light of modern knowledge and investigative techniques.

There are always avenues that are not pursued in any investigation because the experience of the investigators dictates that they will not advance the analysis of what happened. Without that same body of experience it is impossible for an observer to later fully understand the reasons for not following some promising looking lead. Fifty five years on, we are trying to second guess decisions made by people who probably started in air accident investigation eighty years ago. I submit we have little chance of duplicating their thought processes and reasoning at the time although we can make some educated guesses based on modern air accident investigation best practice.

Ignoring the fine details, the ailerons became detached from the control yokes while the aircraft was established in a right bank which steadily increased until the aircraft crashed.

I have no definitive explanation as to how the rear fuselage ended up upside down at the end of the wreckage trail, but some descriptions at the time mention the aircraft somersaulting after the initial impact (post the rail road embankment strike) while breaking apart and shedding wreckage with what was left of the wings and rear fuselage pancaking level, right side up and sliding backwards along the ground. No mention is made of the wreckage spinning or turning, but if it did, then the drainage ditch may have allowed what was left of the aircraft to pitch over upside down. Perhaps this was what gave the impression of a somersault?
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Old 6th Jan 2018, 10:46
  #325 (permalink)  
 
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megan

Thank you. I appreciate why the boost unit could come under suspicion as a contributory factor. If I am not very much mistaken, there are parallels with the original Boeing 737 rudder hydraulic system. Interesting.
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Old 6th Jan 2018, 14:43
  #326 (permalink)  
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Originally Posted by G0ULI View Post
Ignoring the fine details, the ailerons became detached from the control yokes while the aircraft was established in a right bank which steadily increased until the aircraft crashed.
The plane descended on a 5 degree slope over several hundred feet. After hitting a 50-ish foot high embankment it stayed in the air another 380 feet. If the bank steadily increased it should have hit about 1500 feet from where it did. In a steadily increasing bank it should have stalled at about 63 degrees with some 20 degrees more to roll before it hit. A steadily increasing bank should leave a path like a tightening spiral. Instead the path was a loosening spiral, with the plane going 4000 feet to the runway's right and only 2500 feet forward.

I have no definitive explanation as to how the rear fuselage ended up upside down at the end of the wreckage trail, but some descriptions at the time mention the aircraft somersaulting after the initial impact (post the rail road embankment strike) while breaking apart and shedding wreckage with what was left of the wings and rear fuselage pancaking level, right side up and sliding backwards along the ground. No mention is made of the wreckage spinning or turning, but if it did, then the drainage ditch may have allowed what was left of the aircraft to pitch over upside down. Perhaps this was what gave the impression of a somersault?
Possibly. This is the puzzle - how did the plane get to that position? And why did the CAB go public on the day of the crash with a scenario that is clearly wrong? Why was it not corrected in the final report?

I recognize that we're not talking about World Peace here. This doesn't have anything to do with the root cause. It's merely a very curious puzzle. Unwrapping it turned up other interesting bits, like the impossibility of being in a vertical bank at that location on the airport grounds.

I don't criticize the CAB investigators for providing less information than I'd like. I criticize the investigators for putting forth a clear and unambiguous scenario that is provably wrong. I criticize them for sticking to that story for the entire duration of the investigation.
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Old 6th Jan 2018, 15:15
  #327 (permalink)  
 
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A Study in Confirmation Bias

1-6-18

A Study In Confirmation Bias.

Starting with flight path is not preferred. Starting with aircraft and systems is preferred, logs, written notes, eyewitness data.

Flight path as origination of study is not broad enough. What follows is ‘tracking back’, a path that will offer dozens of false trails. It can also lead to bias, as it also fosters a “too early” formation of thesis. The tendency here is to look for confirmation. (Instead of other possibilities)

The AP was found to be “energized”, (ON). The switch was not known to have been guarded, and CAB claim no other means was available To the pilot to provide power to this system.

In pre take off, does the checklist say “CHECK AP OFF”. Or, does it say “Cycle the AP switch, Check AP OFF”

CAB claim by inference that the AP had nothing to do with the accident. Was there any possibility of the AP being (selected) “ON” at takeoff? They state it is unknown whether the AP switch was guarded. (This should be listed in maintenance, relative to “re-install”)

Why was the unit installed in the aircraft? Placarded INOP, why not leave it back at the avionics shop to be repaired?

Possibility:

1. No blank was available to seal the panel shut.
2. As part of the control system, some wiring in the AP was necessary to be present, hard wired to provide continuity for other circuits.
3. Records of AP maintenance? What was the problem?
4. Which channel was inop?
5. Was it the Switch that was the problem?
6. Was the switch powered?

Unfortunately, some one present put the story together within hours, prior to any testing of other potential theses. Also offered without ANY evidence.

Last edited by Concours77; 6th Jan 2018 at 15:55.
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Old 6th Jan 2018, 15:18
  #328 (permalink)  
 
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[QUOTE=megan;10012016]There are no such statements on the nominated pages

megan

I disagree, I have hard copy of five signatures of the CAB beneath these comments.

Nominated Pages. That is an interesting discussion.

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Old 6th Jan 2018, 15:24
  #329 (permalink)  
 
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G0ULI

Here:

“Ignoring the fine details, the ailerons became detached from the control yokes while the aircraft was established in a right bank which steadily increased until the aircraft crashed.”

I agree, but with some caveats. “Detached”. That is CAB’s probable cause. In one theory CAB offered that BOTH primary cables separated, so we need to further define “Detached”? This theory eliminates “Stuck Ailerons” which IMO can not be eliminated. It also eliminates other possibilities that don’t even conflict with the “probable cause” eg jammed, seized, or dismounted boost unit.

edit. “The ailerons became Detached...” that presumes they were “attached” in the first place?” Assuming the right roll was initiated by pilot commanded ailerons is a likely condition. We know the turn was very early, was it pilot commanded?



“I have no definitive explanation as to how the rear fuselage ended up upside down at the end of the wreckage trail, but some descriptions at the time mention the aircraft somersaulting after the initial impact (post the rail road embankment strike) while breaking apart and shedding wreckage with what was left of the wings and rear fuselage pancaking level, right side up and sliding backwards along the ground. No mention is made of the wreckage spinning or turning, but if it did, then the drainage ditch may have allowed what was left of the aircraft to pitch over upside down. Perhaps this was what gave the impression of a somersault?”


Well. The Devil is in the details, eh?

Your “Somersault” is my “Pitch Pole”.

My thesis from a previous post?

Last edited by Concours77; 6th Jan 2018 at 15:52.
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Old 6th Jan 2018, 15:28
  #330 (permalink)  
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Originally Posted by Concours77 View Post
Starting with flight path is not preferred.
Agree. Looking at the flight path came about two years after starting the project.

In pre take off, does the checklist say “CHECK AP OFF”. Or, does it say “Cycle the AP switch, Check AP OFF”
It says Autopilot OFF
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Old 6th Jan 2018, 15:28
  #331 (permalink)  
 
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BRDubois

Craig, would you Post the actual schematic from Lockheed of the boost unit architecture for the Electra?

I have it in the Lockheed manual, but am having difficulty reproducing it.

As to AutoPilot. Perhaps a bad habit, but sometimes check OFF is preceded by Checking ON. If the switch was the problem that precipitated INOP, it may not have returned to OFF.

“I can’t get release... “ Automatic systems are described with specific terminology.

An Autopilot is “Engaged”, or “Disengaged”. A separate term used is “Released”?

Last edited by Concours77; 6th Jan 2018 at 15:43.
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Old 6th Jan 2018, 18:02
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Clearly an aileron roll to the left, or even a return to neutral, was not possible otherwise the aircraft would not have maintained a steadily increasing bank angle and right turn

Left roll was possible. The co-pilot’s cable remained attached. After separation of pilot’s cable, either seat could roll the yoke left, and pulled the Starboard cable for a turn. The yokes are interconnected.

Such a roll left was initiated as soon as the pilot wanted to stop his right roll at thirty degrees. Contrary to CAB, both cables do not fail and bind after one fails. There is an immediate loss of tension on the left, (MAYBE. CAB suggests the cables were not re tensioned after boost unit install), which merges with right cable tension, for a net reduction.

BUT. Each cable is “pinned” (fixed) to its respective column command wheel. Right cable cannot command further right roll, (pilot certainly avoided that) but it CAN command left roll. A further discussion of “aileron loop” is needed. It is not actually an uninterrupted loop.

The lack of any roll left, (which is not known,) cannot be concluded. Eyewitnesses? Certainly not. The problem becomes, no way to stop roll left. As described, the Electra, By Design, returns its control surfaces to neutral without any input. This is trained. It suggests the solution is to release controls, and let the airplane regain (uncommanded) control on its own. Not necessarily Straight and level.

Don’t fall into the trap: right aileron positioned three degrees right wing down.

After IMPACT. Was there a piece of high tension power line caught in the aileron pocket? Finding telltale damage after the path this aircraft undertook, and suggesting to draw a conclusion of flight path is deceptive, sloppy, or simply, ridiculous. This rationale was applied to instrumentation (AI), let’s also apply it to “as found”, post impact.

Last edited by Concours77; 6th Jan 2018 at 18:21.
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Old 7th Jan 2018, 00:23
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BRDubois Check PM and mail.
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Old 7th Jan 2018, 00:24
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Pages twelve, thirteen, and the signature page, fifteen, on the way.

Can you clean up those pages? Not readable.

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Old 7th Jan 2018, 02:08
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Originally Posted by BRDuBois View Post
The plane descended on a 5 degree slope over several hundred feet. After hitting a 50-ish foot high embankment it stayed in the air another 380 feet. If the bank steadily increased it should have hit about 1500 feet from where it did. In a steadily increasing bank it should have stalled at about 63 degrees with some 20 degrees more to roll before it hit.
The CAB report records ground level as 650 feet above mean sea level and the top of the embankment as being 675 feet. The embankment was only 25 feet high in relation to the surrounding terrain. That makes a significant difference to how much of the wing made contact with the embankment. It also has a direct bearing on how much such a contact would modify the flight path and attitude of the aircraft. If the wingtip made contact approximately 12 feet below the top of the embankment, (halfway up), then the loss of the outer 12 feet of the right wing would be expected to further increase the bank angle as the aircraft flew on due to loss of lift.

I use the term "lift" with reference to the direction of aerodynamic forces acting on the wing, a lift vector, but not in the sense of sustaining flight.

The investigators stated that the power lines were severed at some right bank angle between 60° and 70°, although no evidence as to how they derived this angle is included in the report. But this angle combined with a loss of lift from the right wing would lead to the conclusion that the attitude indicator that was recovered with witness marks interpreted as a bank angle around 100° is most likely to be correct.

So the initial impact with the ground beyond the embankment must have been between 5° and 10° nose down with a bank angle to the right of 100°+. Impact forces broke away the nose section and undoubtably the majority of the right wing. That part of the sequence can be stated with some confidence.

At 150 knots or so, the damaged wing of the aircraft would be expected to hit the ground some 250 feet beyond the embankment if it were simply in free fall, as it effectively would be with wings orientated vertically. The nose section another 100 or so feet further on. This fits reasonably well with the 380 feet figure you mentioned as the primary impact point of the aircraft with the ground beyond the embankment.

There is evidence that the remainder of the fuselage and left wing pancaked to the ground in a level and upright position. The only way that this could happen is if the inertia of the left wing and engines rotated the fuselage around to face backwards as it broke away from the nose section.

There appears to be a sudden deviation in the course of the wreckage path after the nose of the aircraft hit the ground. A rotational force being developed by thrust from the left wing engines which were still producing power, together with inertial forces may have been responsible. Gyroscopic forces produced by the still rotating propellers on the left wing should not be neglected as a source of rotational and precession energy either.

I suggest that the rear of the fuselage and left wing therefore impacted the ground like a sycamore seed and continued to slide, rotate and break up before encountering the ditch which imparted a final pitch pole movement to the wing box and tail section, leaving them inverted.

That is to my mind the only sequence that makes sense. With one wing and the nose section missing, the remainder of the aircraft would fit between the trees.

Obviously this would all occur in a matter of a few seconds, but it does broadly fit with the witness testimony appearing as a somersault to some, a flat or spinning impact to others, and of course the final inverted position of the tail pointing in the direction of travel.

All of this does presuppose that the aircraft struck the ground in a bank that was at or beyond vertical. I submit that the evidence available supports that view.

Apologies if I have stolen the wording or contents of other contributers posts in compiling this possible sequence of events, but as this thread seems to be about establishing what happened during the final seconds of the flight, I thought it worthwhile to attempt a summary that fitted the information available.

Last edited by G0ULI; 8th Jan 2018 at 02:32. Reason: Clarification of "lift" and spelling errors.
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Old 7th Jan 2018, 02:19
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Concours77

You have to log in and click on the images to bring them up full resolution, full screen, or refer to a copy of Craig's report.
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Old 7th Jan 2018, 20:13
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CAB, excerpts, flight 706 Final Report

Hi.

With respect, for megan

G0ULI excellent and extremely well written synopsis of the accident.

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Old 8th Jan 2018, 14:02
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Provenance

Source is stamped on the upper margin. Based in Switzerland, and I make no representations as to authenticity of the contents.

Thanks for asking. Yes, it is single spaced. Yes it appears to contradict the pages megan posted.

It also makes a compelling case for cable continuity interruption on the co-pilot side.

This contradicts its (similar) conclusion of pilot side interruption.

The forensic study of co-pilot command cable interruption is conclusive for loss of control cable in flight. However, the cable that is stated to have parted, the “left wing down” cable, is on the pilot side.

I am undertaking a complete analysis of this. A report will follow.
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Old 8th Jan 2018, 15:43
  #339 (permalink)  
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Originally Posted by Concours77 View Post
Source is stamped on the upper margin. Based in Switzerland, and I make no representations as to authenticity of the contents.
Looks right, and the text seems to match the hardcopy I scanned for my report. I didn't remember seeing a single-space report, but after I dug through my directories I found the same PDF. Senior moment.
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Old 8th Jan 2018, 16:11
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megan

Originally Posted by megan View Post
I've reproduced pages 12 & 13 below. Please point out where,
Also on page fifteen, just above the signatures, it is “co-pilot” cable that separates.....

EDIT.
megan,
So. If Co-pilot cable separated, left wing down was available. That is, if the report is incorrect as to which cable is tensioned on the co-pilot side.

Nevermind, the Report claims both cables are tensioned at both sides. Mystery solved!! When did Lockheed modify the single pair system to a dual pair layout?

EDIT.
Craig,
Glad to hear someone else has this.

Last edited by Concours77; 8th Jan 2018 at 16:46.
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