Help researching 1961 Electra crash
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So, as you observe, a change in acoustic pitch of the prop noise would be unusual in normal operation.
Gotta go run errands, back later.
https://ibb.co/nN6UVR is an image of the left wing. The report said it was broken in two places but was present at the final site.
https://ibb.co/nN6UVR is an image of the left wing. The report said it was broken in two places but was present at the final site.
It appears to be a 4” x 4” post, quite old, given the checking at the top. Very old lumber. Perhaps a property marker, or old enough to warrant saving it as a “signpost”. I swear I saw a metal sign at the top, bent in two....
I took it for a piece of debris embedded in the ground. Hard to see someone digging a ditch and then putting a post in the middle of it, or digging a ditch and leaving the post. No other posts in the area.
https://ibb.co/dixuVR is a closeup of it. No sign.
If it predates the crash it shoots down my hypothesis, of course.
https://ibb.co/dixuVR is a closeup of it. No sign.
If it predates the crash it shoots down my hypothesis, of course.
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It does, and likely from sloshed fuel as the aircraft flipped.
Airbubba:
Thanks for the clarification.... the witnesses report seems important, and should have been chased down and examined.
1. “At 8-9000 feet down the runway, the sound changed...”
2. Where were these people located? Doppler may have made a difference.
3. If a mile away, there could have been a five second delay in sound travel.
4. The aircraft may have been at 5-6000 feet down the runway.
5. At 160 knots, how much distance need we allow for?
6. Never having climbed to three hundred AGL, any turn that low would have been important, and when associated with power level changes, the initial “turn” may not have been aileron inspired?
7. Looking at pictures of the aileron command cabling. As shown, these cables can not “unthread”, they are retained by a threaded collet, which prevents twisting either direction. The collet itself is threaded, pinned, clipped and safetied.
8. A loss of boost, or locked boost, in and of itself, can be overcome manually after disabling the pumps.
9. Surely switching off the electric pumps should have been on the memory items?
10. If the aileron was indeed at three degrees on impact, when did it return? Was it under manual control? At what point?
Airbubba:
Thanks for the clarification.... the witnesses report seems important, and should have been chased down and examined.
1. “At 8-9000 feet down the runway, the sound changed...”
2. Where were these people located? Doppler may have made a difference.
3. If a mile away, there could have been a five second delay in sound travel.
4. The aircraft may have been at 5-6000 feet down the runway.
5. At 160 knots, how much distance need we allow for?
6. Never having climbed to three hundred AGL, any turn that low would have been important, and when associated with power level changes, the initial “turn” may not have been aileron inspired?
7. Looking at pictures of the aileron command cabling. As shown, these cables can not “unthread”, they are retained by a threaded collet, which prevents twisting either direction. The collet itself is threaded, pinned, clipped and safetied.
8. A loss of boost, or locked boost, in and of itself, can be overcome manually after disabling the pumps.
9. Surely switching off the electric pumps should have been on the memory items?
10. If the aileron was indeed at three degrees on impact, when did it return? Was it under manual control? At what point?
“As I mention in the document, one reason for putting this out is to see if I can shake some old documentation out of the tree. Some old airline employee or investigator may have something. The National Archives has nothing. Maybe some bystander with a Brownie camera has pictures. Some of this material probably still exists, but I see no path to it except this document and word of mouth......”. BRDubois.
Wasn’t the CAB folded into the FAA? If so, it was, is a Federal agency....
Records of this type of accident are not allowed to be destroyed, IMO.
The FAA will almost certainly have all the data. To get the data requires a filing of FOIA request. “Freedom of Information Requests” are not difficult to file. If the FAA demures, a lawsuit will encourage the release.
I state this in the interest of explaining that our government works for the people. One needn’t demonstrate a need for the data, it must be made available to those who request it.
Wasn’t the CAB folded into the FAA? If so, it was, is a Federal agency....
Records of this type of accident are not allowed to be destroyed, IMO.
The FAA will almost certainly have all the data. To get the data requires a filing of FOIA request. “Freedom of Information Requests” are not difficult to file. If the FAA demures, a lawsuit will encourage the release.
I state this in the interest of explaining that our government works for the people. One needn’t demonstrate a need for the data, it must be made available to those who request it.
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The cable was threaded into a turnbuckle of some kind, but the safety wire was never inserted. They found it after the crash with no wire and no soot marks indicating a wire had been there. I can't attest that this was a valid finding of the root cause, but I'm not at this point questioning it.
As I went through the simulator runs I was increasingly questioning the crew's response. That's an uncomfortable feeling. It seems to me that faster left rudder would have gotten them out of it. I'm still pondering this. The next release will have a lot of material about simulating the flight.
When the CAB was folded into the FAA, all the CAB files went to the National Archives. The Archives verified this, and did a search for all records on this crash. They said there was nothing but the final report. I'm not averse to filing legal motions as needed ...
As I went through the simulator runs I was increasingly questioning the crew's response. That's an uncomfortable feeling. It seems to me that faster left rudder would have gotten them out of it. I'm still pondering this. The next release will have a lot of material about simulating the flight.
When the CAB was folded into the FAA, all the CAB files went to the National Archives. The Archives verified this, and did a search for all records on this crash. They said there was nothing but the final report. I'm not averse to filing legal motions as needed ...
I see the assembly not as turnbuckle, but shackle, there is a difference. A turnbuckle is used to take up slack, not necessary when the cabling is constructed as “lockclad”. In any case, one lead loosening in a turnbuckle tightens it’s counterpart. I have a picture in the manual.
The attachment of the command cable is made by threading a swaged terminus into a collet, which is placed into the opening of a shackle. The collet is then locked into the leaves of the shackle with a pin. The end of the cable can not rotate. If you are familiar with “push pull” controls, you would know that the cable resists “spinning”. The entire length of the cable would “Flemish” into a coil, which is not possible.
Cable slack is addressed specifically by Lockheed with this (patented?) cladding.
The attachment of the command cable is made by threading a swaged terminus into a collet, which is placed into the opening of a shackle. The collet is then locked into the leaves of the shackle with a pin. The end of the cable can not rotate. If you are familiar with “push pull” controls, you would know that the cable resists “spinning”. The entire length of the cable would “Flemish” into a coil, which is not possible.
Cable slack is addressed specifically by Lockheed with this (patented?) cladding.
With the testimony of five separate witnesses as to noise, we assume something of importance was happening as early as liftoff. It may have been a closing of the power levers, an attempt to reject takeoff. That this noise signature apparently coincided with a “turn” is potentially the key to what happened. Losing boost, or boost locked controls are trained in this type exhaustively, that is why the unlocking/relocking of boost levers is at the base of the pedestal, with the takeoff checklist demanding the access flip door be open on launch. I am wondering why the pumps are not shut down as part of the procedure?
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After the main body impact, which detached the engines that hadn't already gone, I guesstimate the plane was about 25,000 lbs lighter and the CG was moved aft maybe twenty feet. I'm tinkering with the simulator (which has a provision for designing your own planes) to see if I can model this.
Hi. After loss of #4 and the wing area with it, wasn’t the next impact the remainder of the right wing? The main wing spar excavated a ditch deeper than the surrounding wing structure? Next impact was the forward fuselage?
Not sure what CG change would do. Why is that important? The structure is not an airplane any longer? All control lost, everything is ballistic?
I understand your investment in establishing an accurate debris propagation. To support your theory of “reducing bank and attempting a belly landing”, I draw attention to the orientation of the right aileron in its pocket when the right wing tip impacted the rising portion of RR embankment.
There was a crushing scar on the outboard face of the inboard pocket rib. Since the embankment was the first ground impact, we can say that the evidence found is at least as worthy as the gyro horizon face, indicating ninety degrees Bank. It is legend to invest sacred truth to obliterated structure, “it impacted at 9:01, that’s where the hands of the clock were....”.
This scar was left by the Alclad hem of the lower skin of the right aileron. It showed the aileron was deflected three degrees in the up (wing down) position. That tells me that not only was roll control regained, but the ailerons were deflected manually, with the three to one mechanical advantage the design afforded. If CAB theory is correct, no such finding can be made. Aileron Control was not totally lost, and they were not “along for the ride”.
Somebody show me a turnbuckle. Make a case for “unthreaded cable”.
I do know Lockheed designed the tankage to minimize CG variation with fuel consumption. The fuel was oriented span wise.
The Electra was a groundbreaking design. I don’t buy the theory that absence of a safety wire brought this aircraft down.
http://dotlibrary.specialcollection....ry=(select+732)
Instructive, but still “the cable unscrewed”. I believe this is a myth. Aircraft cables are robust, and cannot rotate, twist, or unscrew from a threaded connector.
Not sure what CG change would do. Why is that important? The structure is not an airplane any longer? All control lost, everything is ballistic?
I understand your investment in establishing an accurate debris propagation. To support your theory of “reducing bank and attempting a belly landing”, I draw attention to the orientation of the right aileron in its pocket when the right wing tip impacted the rising portion of RR embankment.
There was a crushing scar on the outboard face of the inboard pocket rib. Since the embankment was the first ground impact, we can say that the evidence found is at least as worthy as the gyro horizon face, indicating ninety degrees Bank. It is legend to invest sacred truth to obliterated structure, “it impacted at 9:01, that’s where the hands of the clock were....”.
This scar was left by the Alclad hem of the lower skin of the right aileron. It showed the aileron was deflected three degrees in the up (wing down) position. That tells me that not only was roll control regained, but the ailerons were deflected manually, with the three to one mechanical advantage the design afforded. If CAB theory is correct, no such finding can be made. Aileron Control was not totally lost, and they were not “along for the ride”.
Somebody show me a turnbuckle. Make a case for “unthreaded cable”.
I do know Lockheed designed the tankage to minimize CG variation with fuel consumption. The fuel was oriented span wise.
The Electra was a groundbreaking design. I don’t buy the theory that absence of a safety wire brought this aircraft down.
http://dotlibrary.specialcollection....ry=(select+732)
Instructive, but still “the cable unscrewed”. I believe this is a myth. Aircraft cables are robust, and cannot rotate, twist, or unscrew from a threaded connector.
Last edited by Concours77; 23rd Dec 2017 at 23:07.
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I've wavered on what they might have been attempting. A pilot friend said the plane was doomed to hit, given the aileron deflection. But the rudder can easily counter that aileron, at least per my sim runs. I've phrased it as trying to moderate a descent, trying to at least manage a belly landing. My latest sim runs tell me the 35 degree bank is a highly transient state, and at their speed it should have been easily manageable even with the ailerons still stuck at three degree deflection.
My take on it at this point is that they were descending to keep from stalling, which they would have felt in the higher bank angle. As they got the bank reduced, the danger of stall would have dropped to nothing. So they were trading height for speed when they needed to, and were transitioning to level flight and climbing right about the point they hit the high tension lines. This is what my flight recreation shows.
The point is, they were not trying to do a belly landing, they were trying to stay in the air. It merely LOOKS like a belly landing gone bad, because they ran out of altitude, possibly exacerbated by hitting the power lines.
My take on it at this point is that they were descending to keep from stalling, which they would have felt in the higher bank angle. As they got the bank reduced, the danger of stall would have dropped to nothing. So they were trading height for speed when they needed to, and were transitioning to level flight and climbing right about the point they hit the high tension lines. This is what my flight recreation shows.
The point is, they were not trying to do a belly landing, they were trying to stay in the air. It merely LOOKS like a belly landing gone bad, because they ran out of altitude, possibly exacerbated by hitting the power lines.
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I've discussed this before, but let me recap the rudder issue and knife edge flying. The Electra can knife edge fly at about 250kts IAS. At anything less, the rudder cannot depress the tail against the airflow to lift the nose and cause the fuselage to act as an airfoil.
For any given speed under 250kts, there is some angle at which the rudder can just barely hold its own against the airflow. At any lower angle the rudder can counter the bank and roll the plane level. At any higher angle the rudder is insufficient and the plane will drop its nose. Sim runs tell me this angle is about 60-65 degrees at 160-ish kts. In contrast to knife-edge flying, I call this bevel-edge flying.
My Dad was at about a 57 degree bank at about 160 kts with a rudder whose bank-countering functionality was degraded to just about nothing. They didn't know that; they never trained for it; no one trains for this. But once the rudder took hold and the bank started to flatten, the rudder would have increasing effect. A full left rudder at a 60 degree bank is nothing at all like a full left rudder at 35 degrees. Once the bank starts to flatten, the effect of the rudder will increase exponentially.
This is a little like rolling a ball along the crest of a berm. Once it starts to move to one side or the other, it will accelerate quite quickly. As long as it's on the crest, it might stay there. And simulating this particular instance requires quite a long run along the crest, which then exponentially cascades. I hope that's not too obscure. What it means is that my chances of replicating this with the simulator are virtually nil. I can animate it, but I doubt I can simulate it.
For any given speed under 250kts, there is some angle at which the rudder can just barely hold its own against the airflow. At any lower angle the rudder can counter the bank and roll the plane level. At any higher angle the rudder is insufficient and the plane will drop its nose. Sim runs tell me this angle is about 60-65 degrees at 160-ish kts. In contrast to knife-edge flying, I call this bevel-edge flying.
My Dad was at about a 57 degree bank at about 160 kts with a rudder whose bank-countering functionality was degraded to just about nothing. They didn't know that; they never trained for it; no one trains for this. But once the rudder took hold and the bank started to flatten, the rudder would have increasing effect. A full left rudder at a 60 degree bank is nothing at all like a full left rudder at 35 degrees. Once the bank starts to flatten, the effect of the rudder will increase exponentially.
This is a little like rolling a ball along the crest of a berm. Once it starts to move to one side or the other, it will accelerate quite quickly. As long as it's on the crest, it might stay there. And simulating this particular instance requires quite a long run along the crest, which then exponentially cascades. I hope that's not too obscure. What it means is that my chances of replicating this with the simulator are virtually nil. I can animate it, but I doubt I can simulate it.
I’ve run across some text in the report that raises some questions, potentially very important.
At what point along the trail did the cockpit area separate from the main structure(s)?
I don’t think the aircraft can fly without its right wing, and if #4 plus its supporting wing area impacted at the RR tracks (at an angle) and separated, the next structure to impact would likely be the forward fuselage? Did the fuselage separate? At what station?
Thanks
edit. The video and your description of the Rudder activity show a forward slip. Without aileron, the Rudder must be accompanied with reduction in power on the port wing. The forward slip is a maneuver generally used to lose altitude.
edit’. From the doc. “......Although both mechanics testified that they checked each other's work after completion of the installation, neither one could recall having made a specific cheek (sic) to insure that the previously loosened cable connectors were properly threaded into the slack absorber terminal blocks, the cable tension checked, or the connectors resafetied.....”
Edit’’. From the report, no actual separation of cable from Boost Quadrant was found on pilot’s side. On Co-pilot’s side, “the cables and pertinent structures were not recovered.”
Conclusion: no actual evidence of command cable separation was found. That makes the CAB’s implied finding a THEORY, not a finding of fact....
At what point along the trail did the cockpit area separate from the main structure(s)?
I don’t think the aircraft can fly without its right wing, and if #4 plus its supporting wing area impacted at the RR tracks (at an angle) and separated, the next structure to impact would likely be the forward fuselage? Did the fuselage separate? At what station?
Thanks
edit. The video and your description of the Rudder activity show a forward slip. Without aileron, the Rudder must be accompanied with reduction in power on the port wing. The forward slip is a maneuver generally used to lose altitude.
edit’. From the doc. “......Although both mechanics testified that they checked each other's work after completion of the installation, neither one could recall having made a specific cheek (sic) to insure that the previously loosened cable connectors were properly threaded into the slack absorber terminal blocks, the cable tension checked, or the connectors resafetied.....”
Edit’’. From the report, no actual separation of cable from Boost Quadrant was found on pilot’s side. On Co-pilot’s side, “the cables and pertinent structures were not recovered.”
Conclusion: no actual evidence of command cable separation was found. That makes the CAB’s implied finding a THEORY, not a finding of fact....
Last edited by Concours77; 24th Dec 2017 at 15:21.
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The nose hit about 380 feet past the railroad embankment. The cockpit was crushed and the forward fuselage broke off just in front of the wings. The forward fuselage traveled perhaps a couple hundred feet. What arrived at the final site was the entire left wing (badly fractured), the remains of the right, and the empennage complete.
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Here's a very informal demo.
I've subtracted 25,000 lbs and moved the CG 20 feet aft to adjust for the loss of the engines and the forward fuselage.
I have not actually altered the graphic to show the forward fuselage or engines as missing.
It starts in level flight at 140 kts. It travels roughly 800 feet past the starting point. This is not an animation, it's the flight simulator.
I've subtracted 25,000 lbs and moved the CG 20 feet aft to adjust for the loss of the engines and the forward fuselage.
I have not actually altered the graphic to show the forward fuselage or engines as missing.
It starts in level flight at 140 kts. It travels roughly 800 feet past the starting point. This is not an animation, it's the flight simulator.
The nose hit about 380 feet past the railroad embankment. The cockpit was crushed and the forward fuselage broke off just in front of the wings. The forward fuselage traveled perhaps a couple hundred feet. What arrived at the final site was the entire left wing (badly fractured), the remains of the right, and the empennage complete.
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Wish I had the list of the 22 errors NWA sent to the CAB. Even allowing for corporate efforts to minimize legal or face damage, there must have been something there.
It is likely N137US was released to service with aileron slack. The stainless threaded connector on the pilot’s side was “backed out” of its attachment to the brass junction. Nevertheless, the CAB found all cables attached on the pilot’s side, even though the tensioner side of the flexible cable had but 1/2 inch engagement. Lockheed's test of tension on the aileron connections produced a severed Stainless cable, at 2,000 pounds.
No information on the (connections) valve side of the tensioner, but it was continuous. Loose cabling is suggestive of removal of boost valve and boost unit in the shop. The valve end, a swaged ball fitting, is assumed to have its keeper in place, or the CAB would have noted it.
Without more information, including shop logs, boost unit assembly replacement protocol, and other schematics, we are left to critique the CAB. The actual work in design, maintenance, repair, and design considerations of aileron systems cannot be judged, no data to support any criticism is available.
Lockheed did simulate a fouled aileron, and analysed force required to overcome a trapped aileron, (trapped in this case by the wing flap). A reasonable theory of entrapment could flow from a scenario where the flap, being retracted after lift off, contacted the aileron and pushed it up, creating wing down. If the flap then jammed, the wing is producing a right turn, and the flap is creating chronic drag, perhaps the cause of low angle of climb, and lackluster airspeed. The flap would have contributed to right yaw, especially if the left flap had stowed.
No information on the (connections) valve side of the tensioner, but it was continuous. Loose cabling is suggestive of removal of boost valve and boost unit in the shop. The valve end, a swaged ball fitting, is assumed to have its keeper in place, or the CAB would have noted it.
Without more information, including shop logs, boost unit assembly replacement protocol, and other schematics, we are left to critique the CAB. The actual work in design, maintenance, repair, and design considerations of aileron systems cannot be judged, no data to support any criticism is available.
Lockheed did simulate a fouled aileron, and analysed force required to overcome a trapped aileron, (trapped in this case by the wing flap). A reasonable theory of entrapment could flow from a scenario where the flap, being retracted after lift off, contacted the aileron and pushed it up, creating wing down. If the flap then jammed, the wing is producing a right turn, and the flap is creating chronic drag, perhaps the cause of low angle of climb, and lackluster airspeed. The flap would have contributed to right yaw, especially if the left flap had stowed.