Ed Helicopter Crashes into Glasgow Pub

383LQ4SS said:
You mean between the engines? So that catastrophic engine failure of one does not take out the other?
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Yes.

An uncontained engine or gearbox failure might have quite a bit of force to expend.

In the UAL-232 incident, it was an uncontained turbine failure which took out the shared hydraulic manifold. I'm thinking something similar.
 
On most High bypass jet engine these days there are engineering requirements for the main disc and high energy parts are to be contained in the event of catastrophic failure. I think that requirement may even be due to the accident you mention.

I have no idea if that is true of these small helicopter engines. However...I would think that if the engines did not come apart due to catastrophic failure prior to impact with Clutha that these components should be completely intact even with the impact. The damage, whether catastrophic, mild FOD or none at all in these engines would be nice to know. These components are incredibly tough and doubt they would be damaged catastrophically from what I saw of the helo.
If they they were running at the time of impact I might expect medium to severe FOD damage though. I think much will be gleaned from the condition of the engines...much like the rotor blades.
 
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383LQ4SS said:
Sundy Times: Pilot error theory in Glasgow pub crash

http://www.thesundaytimes.co.uk/sto...e1353357.ece?CMP=OTH-gnws-standard-2013_12_15

Pretty bold article. I hope they have their ducks in a row.
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Me too. But if one is going to speculate at this point (and semi-informed speculation is all that is possible to anyone outside the AAIB, the helicopter manufacturer, or the investigating police), then one has to look at the apparent known facts: 1) Neither the main rotor nor the tail rotor was under powered rotation at the time of impact; 2) There was sufficient fuel in the aircraft for many dozens of minutes of normal powered flight; 3) there was no significant (let alone catastrophic) failure of the engines, gearbox or shafts.

Therefore, it seems almost certain that the ability of both engines to output rotational power was somehow stopped, and that the stoppage was not due to mechanical failure within the engines. In my mind, there are only a small number of possible causal factors still in play:

a) There was a major electrical interruption or malfunction to both engines and/or the engine management system (but this is very unlikely owing to redundancy in the electrical system)

b) There was a partial or full interruption in the delivery of air to the engines (this is also unlikely, owing to the apparent lack of evidence of physical blocking of the air intakes)

c) There was a partial or full interruption in the delivery of fuel to the engines (more conceivable, but I might suggest that each engine might have had an entirely separate fuel delivery system, in order to minimise the possibility of simultaneous fuel shut-off to both engines)

d) There was some sort of pilot input to shut down the engines.


I think it's dangerously irresponsible for the media to be starting to suggest pilot input/error in print, in the absence of incontrovertible evidence that this was a significant causal factor. Even if the journalist in question might have got an inside tip-off from someone on the investigation, I still think it's very poor form to put it in headline print before the full official report comes out. And this report may not be based on a tip-off at all, of course.
 
383LQ4SS said:
When fuel is cut cleanly the engine will wind down. But if pumps are cavitating and surging you can get a few pops before the flame extinguishes if conditions are right. Especially at high power demands. Dont ask me how I know:boggled:
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Looks like we both learned to love the T-58, different versions. :D I don't think he was at a high power setting, setting up for landing in a minute or two, but who knows?
The more this accident is hashed out the more it seems it will be a compound failure with multiple steps vs a single catastrophic event.
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At the moment, I am looking at a fuel flow mess due to the latest bulletin some of the EC135 operators have put out. It has to do with an indication problem, but it is important to note that "warning" system and "indication" system are separate circuits. Even if fuel was not what he thought it was, the warning lights should have gone off if the fuel hit x minutes left.

Even so, with the way the EC 135 tanks work, one should have flamed out first, and a few minutes later, the other.
(Now, if one was already off, and the other quite sooner than he expected ... and he didn't call the tower ... then you get surprise engine dying, with a low inertia rotor head, and you could droop fast due to surprise factor. )

If you are interested, there is an extended discussion about autorotations in that thread over at PPRuNe, and in a thread devoted to that topic alone.

The aero experts and a few test pilots have pointed out that if rotor rpm decays below some percent -- I guess it is model depedent, but something like below 70% -- then not only are the engines stopped, but the blades are stalled and won't unstall. The criticality of keeping Nr in the flyable range is where some are looking for answers.

One poster said NASA and the US Army, back in the 60's, did a test and found that to be true. (Glad I wasn't on THAT test flight ...)
The other thing I realized is that Police helo's that operate over crowded cities have it quite tough when emergencies happen.
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Yep.
LondonJohn said:
1) Neither the main rotor nor the tail rotor was under powered rotation at the time of impact; 2) There was sufficient fuel in the aircraft for many dozens of minutes of normal powered flight; 3) there was no significant (let alone catastrophic) failure of the engines, gearbox or shafts.
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On number three, that is "found so far, on the initial look." They may find some other stuff as they dig deeper.
c) There was a partial or full interruption in the delivery of fuel to the engines (more conceivable, but I might suggest that each engine might have had an entirely separate fuel delivery system, in order to minimise the possibility of simultaneous fuel shut-off to both engines)

d) There was some sort of pilot input to shut down the engines.
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D isn't likely.
C seems to be the way to bet, based on information currently available.
I think it's dangerously irresponsible for the media to be starting to suggest pilot input/error in print, in the absence of incontrovertible evidence that this was a significant causal factor.
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Anything for a scoop. :p
 
Darth Rotor said:
... At the moment, I am looking at a fuel flow mess due to the latest bulletin some of the EC135 operators have put out. It has to do with an indication problem, but it is important to note that "warning" system and "indication" system are separate circuits. Even if fuel was not what he thought it was, the warning lights should have gone off if the fuel hit x minutes left.

Even so, with the way the EC 135 tanks work, one should have flamed out first, and a few minutes later, the other.
(Now, if one was already off, and the other quite sooner than he expected ... and he didn't call the tower ... then you get surprise engine dying, with a low inertia rotor head, and you could droop fast due to surprise factor.)
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According to the BBC the cause of the crash was a fuel supply problem. http://www.bbc.co.uk/news/uk-scotland-glasgow-west-26194408
 
Glasgow is a great city, my thoughts are with the families of the victims.
 
Sunstealer said:
Better to read the actual AAIB report:

http://www.aaib.gov.uk/cms_resources.cfm?file=/AAIB S2-2014 G-SPAO.pdf

If you turn off both transfer pumps then fuel is not going to pass from the main tank into the supply tanks. The engines will then only be able to access whatever is left in those tanks.
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Yes. It appears that both transfer pumps may have been manually switched off at some point (the report states that both pumps were in proper working order, but were for some reason deactivated). The supply tanks therefore ran out of fuel since they weren't being supplied from the main tank, and therefore the fuel delivery to the engined stopped when the supply tanks emptied.

And that chimes with what many of us were suggesting earlier. It appeared after the first interim AAIB report that the only thing that could have caused double engine failure was a failure in the fuel supply (or some sort of deliberate pilot input). And since there is redundancy built into the fuel supply as well, it would have required some other mechanism to cause the fuel supply to both engines to fail. In this case, it appears that somebody for some reason set the two transfer pump switches to "off".

The other major mysteries are those surrounding the automatic warning mechanisms, and the pilot's inputs and actions post engine flameout. Warning lights and noises should have kicked in as the supply tank fuel levels got low, and this in itself should have prompted the pilot to check the transfer pump settings. And it appears that once the engines flamed out, the pilot failed to follow even the most basic procedures. He had ample altitude and attitude to have performed a safe and survivable hard landing. He also should have radioed an emergency message. He did none of these things. Can that be put down to bad training, momentary panic or sheer incompetence? Or is there something else at work?

I suspect that the AAIB is a) taking plenty of time on what should be a fairly simple accident investigation (it is a small and relatively simple aircraft, and the wreckage was easily recoverable and in a tightly confined area), and b) releasing interim information, for one main reason: I suspect that they (the AAIB) may be concerned that the primary underlying cause of the crash was pilot error, and I also suspect that they may harbour some sort of feeling that some or all of the errors may have been deliberate. I hope I am wrong, especially in regard to the second half of that previous sentence.
 
LondonJohn said:
I suspect that they (the AAIB) may be concerned that the primary underlying cause of the crash was pilot error, and I also suspect that they may harbour some sort of feeling that some or all of the errors may have been deliberate. I hope I am wrong, especially in regard to the second half of that previous sentence.
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I share your hope, of course. But "deliberate"? What a dreadful idea.
 
Somewhat depressing to see all the media reports are focussing on the "flame out", rather than having anyone competent to spot the significant fact that the supply tanks were empty, and why. Not all that surprising, though, it's been my experience with every newspaper report I've seen where I had knowledge of the real event that the journalist will give entirely the wrong impression. (The most recent example was, sadly, also an air accident.)
 
zooterkin said:
Somewhat depressing to see all the media reports are focussing on the "flame out", rather than having anyone competent to spot the significant fact that the supply tanks were empty, and why. Not all that surprising, though, it's been my experience with every newspaper report I've seen where I had knowledge of the real event that the journalist will give entirely the wrong impression. (The most recent example was, sadly, also an air accident.)
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Yes, exactly my observation too. And it's even worse when the larger media organisations have people who term themselves "science correspondent" and so on.

When I worked in equity research, I used to talk with journalists quite often, either in background briefings or proper interviews. I was absolutely astonished that many of them had very little grasp of basic economics or the business dynamics of the industries they were covering. For example, I spoke with the very high-profile City editor of ITN (as was) a couple of times, and he did not (and could not) understand the concept of "enterprise value" as the correct comparator when analysing takeovers (as opposed to market capitalisation). And he was the City editor of one of the UK's major media organisations! Some of the other journalists - most of whom worked on the business sections of national newspapers - couldn't understand or analyse basic financial statements, and nor did many of them have any idea how the financial markets really worked.

And don't get me started on the media coverage of the Meredith Kercher murder trial :D
 
Craig B said:
I share your hope, of course. But "deliberate"? What a dreadful idea.
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I know - it really is.

But it's extremely difficult to explain how the pilot seemingly didn't react to the warning lights/alarms as the supply tanks ran low, and how he then failed to react properly in any way to the eventual flame out.

The fact that there must have been these two separate incidents, separated in time and in seriousness, is in my view the most curious thing. It is, for example, possible to see how, if the flameouts had occurred suddenly and with no prior warning, the pilot might have either panicked or frozen (although of course it's a crucial part of training and evaluation to ensure that a pilot remains calm and follows the correct procedures in such an event).

But here there must have been the initial warning that the supply tanks were running low, followed (presumably at least five minutes later) by the flameouts as the supply tanks finally drained. In addition, the fuel gauges would have constantly shown the pilot the situation in the main and supply tanks. The pilot's reaction to the initial low-fuel alarms should have been to run through the standard checklist - one of the the first items of which would almost certainly have been to check whether the transfer pumps were switched on. I suspect that it would also have been standard protocol for the pilot to radio the situation. Instead, there was radio silence and the pilot appears to have done nothing to remedy the situation.

And even then, even if the pilot was unable to fix the problem, he should still have had ample time to put the aircraft down safely before the supply tanks finally drained. Instead, he apparently continued flying in a normal fashion until the supply tanks finally ran dry.

And even then, he could and should have been able to make a safe hard landing, as well as radioing the emergency. Instead, once again, there was no radio contact and apparently no attempt to make a controlled descent and landing. And all the while, apparently, the transfer pump switched remained in the "off" position.

It's difficult to reconcile this series of events (and non-responses), and the length of time over which they must have happened, with simple pilot error or temporary pilot paralysis. Could everyone in the cabin have been overcome by something which incapacitated them all? Hard to believe, since the helicopter was in controlled flight up to the flameout point. What else might have produced the known evidence? I hope the AAIB can find out.
 
What it looks like to me is that he hovered in one spot and then made a B-line to the helipad. It appears to me that he had his fuel alarms at the hover spot.

I an noting that the fuel transfer pump switches are not called out as guarded. Given the effect of these being switched off in flight, why are they not?

Is there a cockpit layout diagram somewhere?
 
LondonJohn said:
I know - it really is.

But it's extremely difficult to explain how the pilot seemingly didn't react to the warning lights/alarms as the supply tanks ran low, and how he then failed to react properly in any way to the eventual flame out.
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Wasn't there a crash where all three pilots ignored visual and verbal warnings, because they were focused on a warning lamp that had blown, and didn't notice that the autopilot had been disengaged? It's possible to concentrate on one thing so much that you just don't notice something that would appear to be un-ignorable. Of course, pilot training should aim to overcome this, but it can clearly happen.
 
zooterkin said:
Wasn't there a crash where all three pilots ignored visual and verbal warnings, because they were focused on a warning lamp that had blown, and didn't notice that the autopilot had been disengaged? It's possible to concentrate on one thing so much that you just don't notice something that would appear to be un-ignorable. Of course, pilot training should aim to overcome this, but it can clearly happen.
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Look at what happened in Kegworth. It would be funny if lots of people hadn't been killed unnecessarily.
 
For increased clarity, here are the fuel transfer pump switches outlined with a red ring:

 
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