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Helicopter down outside Leicester City Football Club

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Helicopter down outside Leicester City Football Club

Old 31st Oct 2018, 22:03
  #401 (permalink)  
BFM
 
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Dear all, I am SLF but have been flown by experts in such aircraft and have a bit of experience in crash reconstruction. My I start with condolences to all in this tragedy? I have studied the sad Sun video closely, and I am struck by the appearance of the tail anticollision light as the aircraft rotates. There are two clear images of this. In the first, at almost exactly the 1 minute mark, the image is blurred by the spinning tail rotor.
In the second, about 2 seconds later, the tail anticollision light is small and apparently not blurred. Would a suggestion that this was now due to the rate of rotation of the tail rotor having reduced be reasonable?
Regrettably I cannot post my screen captured images as the forum thinks I am trying to post URLs.
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Old 31st Oct 2018, 23:21
  #402 (permalink)  
 
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Originally Posted by BFM
...and I am struck by the appearance of the tail anticollision light as the aircraft rotates..
The light is not omni-directional, don't assume it's a point source shining equally in all directions. And therefore as the aircraft rotates and pitches etc the light might be blocked on that observational angle by parts of the aircraft, or it just might not shine in a particular direction by design. It's very difficult to drawn any conclusions from the light.
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Old 31st Oct 2018, 23:26
  #403 (permalink)  
 
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Originally Posted by The Old Fat One
..As for journalists stepping by and picking up and printing horse manure...seriously who the heck cares? Surely all educated people know that a large percentage of what is printed these days in newspapers is agenda-led, headline-grabbing codswallop, irrespective of the subject matter. Sure it will influence Joe Public, but that's going to happen regardless of anything that is posted on here.
That's right. Only yesterday Sky News slyly used file vision of an AirAsia plane getting fished out of the Java sea from 2 years ago and fobbed that off as the Lion Air plane that crashed on Monday morning.
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Old 31st Oct 2018, 23:38
  #404 (permalink)  
 
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For those interested in survivability in a similar accident, I refer to this report into a photo flight where and EC130 from a hover, spun from 220 feet and crashed into sand dunes. Even with the EC crash absorbing seats 3 passengers and pilot perished. There was no fire. The report goes into detail regarding vertical G forces.

https://www.onderzoeksraad.nl/en/ond...725A7A690814F2

The crash was recorded on video from a distance so the rate of descent is accurate.
Note that pictures of the wreck show the cabin forward of the seats missing, it appears this was done to remove one of the passengers whose limb was trapped rather than being sliced by rotor impact.

Mjb
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Old 31st Oct 2018, 23:38
  #405 (permalink)  
 
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Originally Posted by Torquetalk
Post 387 above addresses this
I remain to be convinced by that explanation....I've never seen a PWC engine do that before, and I've seen many many starts over many years (but not on this particular model engine). During the start cycle of this engine do the igniters energize as soon as the starter is engaged? I suspect so, so if that was fuel being blown out the engine I'd expect it to be like a flame thrower and not smoke like. To me that looks like oil smoke, from oil that has leaked past a seal that shouldn't. And leaking seals can turn into bad bearings. And bad bearings can turn into failed engines.
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Old 31st Oct 2018, 23:46
  #406 (permalink)  

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The result of a failed engine would not be as per that seen in the videos. A poor igniter can result in fuel vapour being emitted from the exhaust during the start sequence of many turbine engines - obviously there is more than one igniter.
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Old 31st Oct 2018, 23:57
  #407 (permalink)  
 
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Having viewed all the videos, photos and links on this thread, I am unable to see any obvious external faults with the aircraft or its handling until the turn is initiated while in an effective hover at the top of the ascent.

Given that the engines would have been operating at or close to maximum power in sustaining the hover, is it possible that the effectiveness of the tail rotor was critically reduced just as something distracted the pilot just for a second while the rotation rate increased?

Is there a preferred turn direction? Would the aircraft have survived if the turn had been made in the opposite direction? Is the tail rotor authority sufficient to arrest a spin in either direction while in a high hover?

It seems to me that with no forward velocity, once the aircraft started spinning, there was simply no way to go other than straight down.
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Old 31st Oct 2018, 23:57
  #408 (permalink)  
 
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White “smoke” on start: I’m surprised by the comments on here. White “smoke” on start is fairly normal and is fuel sprayed out before the igniters have lit it. Seen it often.
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Old 31st Oct 2018, 23:58
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Originally Posted by gulliBell
I remain to be convinced by that explanation....I've never seen a PWC engine do that before, and I've seen many many starts over many years (but not on this particular model engine). During the start cycle of this engine do the igniters energize as soon as the starter is engaged? I suspect so, so if that was fuel being blown out the engine I'd expect it to be like a flame thrower and not smoke like. To me that looks like oil smoke, from oil that has leaked past a seal that shouldn't. And leaking seals can turn into bad bearings. And bad bearings can turn into failed engines.
It is hard based on what is currently known to see any likely connection between a brief emission from one of the exhausts and what happened afterwards. When I saw it, I thought perhaps coking might have caused it, which was also one of the possibilities suggested in post 387.
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Old 31st Oct 2018, 23:58
  #410 (permalink)  
 
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One thing that puzzles me here (and has done in the past)... WHY are the throttles placed in the ceiling, essentially unreachable if you're already in the middle of sorting out an emergency that needs hands on the collective and cyclic? It would make me horribly uncomfortable if I couldn't control the engines at the same time as everything else. The "motorcycle" throttle on the collective just seems such an obviously good idea. I can see a practical problem for a twin (like, needing two throttles) but I'm sure that's not beyond the imagination of man.
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Old 1st Nov 2018, 00:01
  #411 (permalink)  
 
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Originally Posted by n5296s
One thing that puzzles me here (and has done in the past)... WHY are the throttles placed in the ceiling, essentially unreachable if you're already in the middle of sorting out an emergency that needs hands on the collective and cyclic? It would make me horribly uncomfortable if I couldn't control the engines at the same time as everything else. The "motorcycle" throttle on the collective just seems such an obviously good idea. I can see a practical problem for a twin (like, needing two throttles) but I'm sure that's not beyond the imagination of man.
There are no throttles, only on/off switches. There should be no need to suddenly access the engine controls. In theory...
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Old 1st Nov 2018, 00:16
  #412 (permalink)  
 
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Originally Posted by n5296s
...WHY are the throttles placed in the ceiling...
For helicopters with mechanical plumbing that connects moveable throttles to the engines, it's a simpler installation when the throttles are on the ceiling. But many modern helicopters now just use electrical controls and switches.
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Old 1st Nov 2018, 08:59
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Originally Posted by 212man
thats an understatement! I can hardly bear to visit this thread. I’ve never seen such bollocks!!!
It's long been like that on pprune. These crash threads are useful for finding links to external sites, but the conjecture ranges from laughable to infuriating and, in most cases, just demonstrates a spectacular lack of knowledge.

I don't know that many professionals in the industry, but I do know that anyone with an opinion worth listening too wouldn't post anything on here.
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Old 1st Nov 2018, 10:09
  #414 (permalink)  
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My thoughts keep reluctantly focussing on sabotage. Swift removal of TRGB drain plug?
all billionaires cultivate serious enemies.
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Old 1st Nov 2018, 11:06
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Could the aircraft have responded in the manner seen on the video as a result of pilot incapacitation?
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Old 1st Nov 2018, 11:16
  #416 (permalink)  
 
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Originally Posted by Arkroyal
My thoughts keep reluctantly focussing on sabotage. Swift removal of TRGB drain plug?
all billionaires cultivate serious enemies.
You seem to be the only one - see mine of 30/1902, then #294 now #287 or less.
I hope the police know everyone's name who had access to the aircraft after it arrived at the stadium. I hope the investigators would recognise the signs of noxious products in the cabin.
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Old 1st Nov 2018, 11:17
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Originally Posted by flyems
Could the aircraft have responded in the manner seen on the video as a result of pilot incapacitation?
I think that has to be a possibility when faced with an aircraft with less than 300 hrs flight time and a single crew pilot aged 53. This is why the medical requires more frequent ECGs with age. Having said that, an ECG pass, doesn't mean you are not going to be incapacitated by a stroke or heart attack at anytime. That is why it is always better to have two qualified and type rated pilots, which is the case with the queens flight.
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Old 1st Nov 2018, 11:23
  #418 (permalink)  
 
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Originally Posted by flyems
Could the aircraft have responded in the manner seen on the video as a result of pilot incapacitation?
Originally Posted by Arkroyal
My thoughts keep reluctantly focussing on sabotage. Swift removal of TRGB drain plug?
all billionaires cultivate serious enemies.

Unlikely that incapacitation could cause a reaction like that. and the coroner in the Bournmouth crash seemed to be dreamimg. The ATC tapes that recorded the pilot talking to himself, trying to talk himself out of the loss of control made things fairly clear as to what happened. In fact I belive the ATCO dealing with the flight didn't work for some time due to word she heard.

SND
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Old 1st Nov 2018, 11:30
  #419 (permalink)  
 
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Originally Posted by gulliBell
I remain to be convinced by that explanation....I've never seen a PWC engine do that before, and I've seen many many starts over many years (but not on this particular model engine). During the start cycle of this engine do the igniters energize as soon as the starter is engaged? I suspect so, so if that was fuel being blown out the engine I'd expect it to be like a flame thrower and not smoke like. To me that looks like oil smoke, from oil that has leaked past a seal that shouldn't. And leaking seals can turn into bad bearings. And bad bearings can turn into failed engines.
I understand where you are coming from gulliBell - but having watched, watched and watched again I am convinced that is fuel. Admittedly over-fuelling should not occur, even more so with FADEC equipped machines, but it clearly has in this case - now whether it is caused by unburnt fuel from the previous flight, or fuel being introduced too early, I for one cannot speculate as I am not type rated on my engineers ticket on the 169. For the aircraft which I AM engineer type rated, the introduction of fuel in comparison to ignitor activation varies from type to type in some cases from variant to variant. Hell I've seen the same engine installed on different airframes started with different sequences!

What we can deduce is that an engine failure would not normally result in a fully developed torque induced spin as in this case; however I am far more experienced as an engineer than I am as a pilot, so if someone with more flying experience wants to point out why an engine failure would result in a spin, please do so and educate me. A day without learning is a day wasted after all!!
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Old 1st Nov 2018, 11:54
  #420 (permalink)  
 
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Originally Posted by Arkroyal
My thoughts keep reluctantly focussing on sabotage. Swift removal of TRGB drain plug?
all billionaires cultivate serious enemies.
I live in Leicester just a few miles from where the tragedy occurred. As the various news services have shown an incredible number of people have been involved in the mourning of the enormous loss to Leicester. Minor and major TV, radio and newspapers have actively interviewed helicopter pilots (largely ex-military Lynx pilots) and people involved with Vichai’s various interests. Absolutely nobody has suggested that any foul play/sabotage was involved – there was absolutely no reason. The almost universal guess of the pilots interviewed was that there was a mechanical gearbox failure of some sort at the worst part of Dead Man’s Envelope and that the end was inevitable. I flew Alouettes 55 to 60 years ago and was not allowed to make high vertical departures unless it had been a serious medical emergency that demanded it.

I have recently flown frequently as a helicopter passenger on numerous occasions in both Switzerland and Australia and the pilots would not land if they could not get a good run for take off without high obstruction in front.
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