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Kobe Bryant killed in S76 crash

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Kobe Bryant killed in S76 crash

Old 4th Feb 2020, 20:58
  #481 (permalink)  
 
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Originally Posted by sandiego89 View Post
Post 329 if fraught with problems, and purely speculation on the attitude, I would not put much credence into it. The 329 poster says the main rotor blades can be seen at the start of the impact site, but they seem to be clearly in the middle at least to me (red and white painted rotor elements). A high speed impact, during a turn in hilly terrain is going to be an extremely violent, tumbling, incident.
Fair enough sandiego89 .... I agree that I should have said the blades are JUST PAST the impact zone (in my original post I said AT the impact zone) .

But I still speculate the machine must have been mostly inverted (blades hit the dirt first) because they all broke off (rather cleanly) and at the same time (at impact crater) ...... then they would have bounced a bit to where they are in middle of the picture .... and the main fuselege traveled a bit farther because of the larger mass .

In any other scenario , such as a steep turn , the blade tips would hit first and sections of blade would fly off in all directions away from the main site.

I cannot think of any other way the blades could all be completely severed and remain in one spot. Hope that makes sense. Thanks.

.



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Old 4th Feb 2020, 20:59
  #482 (permalink)  
 
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Originally Posted by gulliBell View Post
Just to be clear, even if there was an engine problem, it doesn't require an immediate landing or cause a loss of control. There is another engine with plenty of power available to keep you humming along just fine. Even if you have an engine on fire, just let it burn until you are safely transitioned to single engine flight. There is no hurry to rush anything. When you are safely flying and assured of terrain clearance, you have two fire bottles that discharge into the engine bay. If those two bottles of fire retardant don't put out the fire, the engine bay is fire rated for 15 minutes. Gives you plenty of time to get it on the ground safely. So these reports of engine spluttering or whatever. Total bollocks. Engine problems are a total furphy in explaining an apparent loss of control.
To my knowledge, certification standards (Part 29 in this case) have never stipulated a 15-minute time period. Has the manufacturer stated that time period?
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Old 4th Feb 2020, 21:02
  #483 (permalink)  
 
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It may be but the Coriolis illusion is normally the result of abrupt head movement after being in a steady state turn for some while - not sure it fits the picture here but it is a possibility.
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Old 4th Feb 2020, 21:41
  #484 (permalink)  
 
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Originally Posted by Arnie Madsen View Post
Fair enough sandiego89 .... I agree that I should have said the blades are JUST PAST the impact zone (in my original post I said AT the impact zone) .

But I still speculate the machine must have been mostly inverted (blades hit the dirt first) because they all broke off (rather cleanly) and at the same time (at impact crater) ...... then they would have bounced a bit to where they are in middle of the picture .... and the main fuselege traveled a bit farther because of the larger mass .

In any other scenario , such as a steep turn , the blade tips would hit first and sections of blade would fly off in all directions away from the main site.

I cannot think of any other way the blades could all be completely severed and remain in one spot. Hope that makes sense. Thanks.

.


I've seen an estimate that the rotor turns at around 350 RPM; if that is wrong then the rest of this will be too, by whatever the proportion of error is in that number. That means that the rotor is turning at nearly 6 rotations per second, (350/60), so 1/6th of a second for a full rotation. If the copter was going say, 150 mph, that's 220 feet per second, so one rotation would be amount to 44 feet of travel. As each of the 4 blades strike the ground, the next blade would hit at 1/4 of that, or about 11 feet. The blades are 22 feet intact, so the over lap could be 50%.

The blades would have some forward momentum, but they would all have the same momentum, and should end up roughly the same distance from their individual initial impact sites. The large imbalance in the rotor head could have quickly dispatched that connection to the drive; it is different than most blade shedding that I've seen videos of where the pilot would be involved in shutting off power and the rotor head remains with the helicopter fuselage even as blades are flung from the accident. In those cases the imbalance causes each blade impact to be in a different location as the fuselage pivots on the ground. In this case, there is the distinct possibility that nearly 1300 shaft horse power was being dumped into the rotor at the same time the unbalance was increasing and with the last blade left, broke that connection, allowing the momentum of the stubs to carry the rotor head separately. If the blades were striking on the retreat side their velocity relative to the ground would be largely reduced, not nearly to zero by any means, but a lot.

tl;dr I would discount the helicopter being inverted at the crash site; It looks more like the main fuselage crumpled at an initial impact, allowing the rotor blades into substantially level contact with the tips hitting the hillside, and the engine and drivetrain, tailcone, and rotor head separating and continuing on, carried by momentum to their various end points. It just appears unusual because it's a rare type of crash. An open field accident, chopper stationary on the ground, usually flings blades randomly, but this only shares that a helicopter was involved.
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Old 4th Feb 2020, 21:42
  #485 (permalink)  
 
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" This is not just disorientation and it is not the leans, but a full-blown sensation of spinning about all three axes."

This sounds like what it can be like if you have ever been in a Barany chair which is a vertigo inducer training device. The chair spins smoothly while you wear a blindfold. Youn re told to put your head in various positions and asked to determine direction of spin etc. By far the most dramatic and frightening demo was where they had you lower your chin by your chest for a while as the instructor spins, stops spins in the other direction and eventually tells you to raise your head. The sensation is best described as feeling like you've been pitched from your pilot seat, out of the helicopter in a hover at altitude. It made me make noises I've never made before and grip the chair, although that made no difference. The instructor then pulled off my blindfold to allow the rest of the class to see my eyes, which were uncontrollably darting around for several long seconds before I almost fell out of the chair. It was so unnerving as to instantly change my perspective ( no pun intended) on spatial disorientation. You sort of think you know how to deal with it but after this demo I'm not sure I want to find out.

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Old 4th Feb 2020, 22:37
  #486 (permalink)  
 
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Originally Posted by JimEli View Post
To my knowledge, certification standards (Part 29 in this case) have never stipulated a 15-minute time period. Has the manufacturer stated that time period?
§29.861 Fire protection of structure, controls, and other parts.
Each part of the structure, controls, and the rotor mechanism, and other parts essential to controlled landing and (for category A) flight that would be affected by powerplant fires must be isolated under § 29.1191, or must be—
(a) For category A rotorcraft, fire- proof; and
(b) For Category B rotorcraft, fire- proof or protected so that they can per- form their essential functions for at least 5 minutes under any foreseeable powerplant fire conditions.
[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as amended by Amdt. 27–26, 55 FR 8005, Mar. 6, 1990]

(And ”Fire proof” should be associated with a test flame temperature of 2000 degrees F for at least 15-minute duration...)
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Old 4th Feb 2020, 23:03
  #487 (permalink)  
 
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It has been a very long time since a pilot has discovered a new way to crash an aircraft. There is nothing new here. The pilot lost control of the situation in low visibility conditions, for whatever reasons. It happened twice two weeks ago in our country and five good people died, and it will continue to happen whilst pilots push their personal limits.
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Old 5th Feb 2020, 06:09
  #488 (permalink)  
 
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Squawk, well said.
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Old 5th Feb 2020, 08:03
  #489 (permalink)  
 
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HissingSid, you experienced what some call "the matrix effect".
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Old 5th Feb 2020, 09:54
  #490 (permalink)  
 
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Originally Posted by JimEli View Post
To my knowledge, certification standards (Part 29 in this case) have never stipulated a 15-minute time period. Has the manufacturer stated that time period?
Via our training pipeline custodian of all S76 knowledge, 2000 degrees and 15 minutes. We've been teaching that in our ground school courses for years.
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Old 5th Feb 2020, 10:00
  #491 (permalink)  
 
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Originally Posted by Arnie Madsen View Post
...But I still speculate the machine must have been mostly inverted (blades hit the dirt first) because they all broke off (rather cleanly) and at the same time (at impact crater) ...... then they would have bounced a bit to where they are in middle of the picture .... and the main fuselege traveled a bit farther because of the larger mass .
They were my initial thoughts exactly as soon as I saw the drone overhead debris dispersion. And the reasonably circular 44 ft wide brush cutting effort.
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Old 5th Feb 2020, 12:15
  #492 (permalink)  
 
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Via our training pipeline custodian of all S76 knowledge, 2000 degrees and 15 minutes. We've been teaching that in our ground school courses for years
Authoritative reference please, not all that's taught is legit.
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Old 5th Feb 2020, 12:30
  #493 (permalink)  
 
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Originally Posted by roscoe1 View Post
By far the most dramatic and frightening demo was where they had you lower your chin by your chest for a while as the instructor spins, stops spins in the other direction and eventually tells you to raise your head. The sensation is best described as feeling like you've been pitched from your pilot seat, out of the helicopter in a hover at altitude.
Indeed. We were subjected to this in initial training, which meant that I had a chance of recognising it. Does everyone have this experience today?

Originally Posted by [email protected] View Post
It may be but the Coriolis illusion is normally the result of abrupt head movement after being in a steady state turn for some while.
That is the demonstration as described by Roscoe, but I do not think the physics requires the steady state to cause the illusion.
Before posting I looked at a lot of sites about the Coriolis Illusion and there seem to be two distinct descriptions, copied almost word-for-word from site-to-site. The first is like yours and the second like mine. Wikipedia, for instance, is like mine.

Originally Posted by Squawk7700 View Post
It has been a very long time since a pilot has discovered a new way to crash an aircraft. There is nothing new here.
Whatever the cause it is unlikely to be new, but how prepared are helicopter pilots these days, to cope with the somatogyral illusions?
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Old 5th Feb 2020, 12:46
  #494 (permalink)  
 
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Originally Posted by Search&Rescue View Post
§29.861 Fire protection of structure, controls, and other parts.
Each part of the structure, controls, and the rotor mechanism, and other parts essential to controlled landing and (for category A) flight that would be affected by powerplant fires must be isolated under § 29.1191, or must be—
(a) For category A rotorcraft, fire- proof; and
(b) For Category B rotorcraft, fire- proof or protected so that they can per- form their essential functions for at least 5 minutes under any foreseeable powerplant fire conditions.
[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as amended by Amdt. 27–26, 55 FR 8005, Mar. 6, 1990]

(And ”Fire proof” should be associated with a test flame temperature of 2000 degrees F for at least 15-minute duration...)
Very good. FWIW, those are the current regulation/guidance. At the time of the S-76 certification, (category B occurred in 1978, and category A followed in 1979), there was no quantified definition of “fireproof.” In 1993, the FAA published AC33-2B, which stated:

The FAR Part 1 definitions of “fire-resistant” and “fire proof” are very broad and are not quantified in terms of flame temperature and time of immersion. For purposes of engine certification, fire resistant should be associated with a test flame temperature of 2000 degrees F, for at least a 5-minute duration; fireproof should be associated with a test flame temperature of 2000 degrees F, for at least a 15-minute duration.
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Old 5th Feb 2020, 16:38
  #495 (permalink)  
 
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FWIW, the rotor blades are not all in one spot. The rotor head itself is 100' or so on the far side of the fuselage. There's a large piece of rotor blade a couple hundred feet beyond that. You can see both on the news copter footage shot right after the crash.

Last edited by dukesahazard; 5th Feb 2020 at 16:49.
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Old 5th Feb 2020, 17:36
  #496 (permalink)  
 
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Originally Posted by gulliBell View Post
Just to be clear, even if there was an engine problem, it doesn't require an immediate landing or cause a loss of control. There is another engine with plenty of power available to keep you humming along just fine. Even if you have an engine on fire, just let it burn until you are safely transitioned to single engine flight. There is no hurry to rush anything. When you are safely flying and assured of terrain clearance, you have two fire bottles that discharge into the engine bay. If those two bottles of fire retardant don't put out the fire, the engine bay is fire rated for 15 minutes. Gives you plenty of time to get it on the ground safely. So these reports of engine spluttering or whatever. Total bollocks. Engine problems are a total furphy in explaining an apparent loss of control.
And one last thing...I hear advice similar to this espoused everywhere. And I agree that response could be too hurried, inducing error. But hesitation can easily be taken too far, or employed with an attitude too cavalierly. In a jet aircraft with podded engines, the advice seems more practicable, however, consider the location and distance between engines in your helicopter, with the likelihood of subsidiary complications. Most engine fire emergency procedures dictate the immediate establishment of OEI flight and extinguishing without delay.

FWIW, this S-76 accident somewhat highlights this, wherein the NTSB determined the probable cause(s) to be the pilots' delayed response to an engine fire warning…
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Old 5th Feb 2020, 18:39
  #497 (permalink)  
 
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That is the demonstration as described by Roscoe, but I do not think the physics requires the steady state to cause the illusion.
Syd, as I understand it the steady state is required because the semi-circular canals stop sensing movement because there is no acceleration in any plane to create the sense of movement - when the head is suddenly moved there is acceleration and hence the confusing sensations in the balance organs.

Whatever the cause it is unlikely to be new, but how prepared are helicopter pilots these days, to cope with the somatogyral illusions?
British Army pilots are required to undergo disorientation training in the air on an annual basis.

Brit Mil pilots all go through similar training at RAF Henlow.
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Old 5th Feb 2020, 19:20
  #498 (permalink)  
 
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Originally Posted by megan View Post
Authoritative reference please, not all that's taught is legit.
I'll defer to post #486. But it wouldn't have been put in our course without an authoritative source.
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Old 5th Feb 2020, 23:58
  #499 (permalink)  
 
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gulli, there's authoritative, and then there's authoritative, FSI disseminated some duff gen once upon a time, as does our wonderful CASA still. You'll no doubt remember the -92 run dry capability sprouted by SK in its advertising.
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Old 6th Feb 2020, 05:58
  #500 (permalink)  
 
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Originally Posted by megan View Post
gulli, there's authoritative, and then there's authoritative, FSI disseminated some duff gen once upon a time, as does our wonderful CASA still. You'll no doubt remember the -92 run dry capability sprouted by SK in its advertising.
Yes, grant you that. Given our FSI links, and their Sikorsky factory links, it's quite possible most roads lead to Stratford CT.
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