Ed Helicopter Crashes into Glasgow Pub

I Ratant said:
"not turning" is instant plummet!
Jammed final gear drive?
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quote from above:

and indicated that the main
rotor gearbox was capable of providing drive from the
No 2 engine power turbine to the main rotor and to the
fenestron drive shaft.
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Thats a fairly positive statement that the entire driveline was operational.
 
BenBurch said:
It is probably not possible to exclude pilot error, but we have no reason at all to suspect it in this case.
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It needn't, of course, just be pilot error. It isn't impossible that he might have died or fallen unconscious, and who knows what a slumped body might do to the controls of a helicopter. The air accident investigators are pretty thorough folk, so all idle internet speculation will be trumped by evidence eventually.
 
MikeG said:
It needn't, of course, just be pilot error. It isn't impossible that he might have died or fallen unconscious, and who knows what a slumped body might do to the controls of a helicopter. The air accident investigators are pretty thorough folk, so all idle internet speculation will be trumped by evidence eventually.
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I always said that post mortem was going to be a tricky job. Presumably they looked for heart attacks and strokes and so on. His body was released to his family a week ago, though, without any announcement of interesting findings.

Rolfe.
 
Pulvinar said:
Suicide by copter?
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I would like to say, out of the question, but after the Moorgate tube disaster, one can't really rule anything out a priori.

Newsnicht in 20 minutes, might get a bit more information.

Rolfe.
 
mummymonkey said:
Might an electrical failure be a possibility?
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Very unlikely. The powerplant is also the generator, and there will be a battery and an auxilliary power unit as well. So just as with a family car, if the engine is running, there will by definition be electrical power available, and even if the alternator/generator breaks, there will be sufficient battery power and APU power available to fly for some time and make a safe landing.

I would think that the most likely explanations at this point are either a) some sort of catastrophic failure in fuel delivery, or b) some form of pilot input. I hope that it's (a), and eyewitness accounts of what they allegedly saw and heard ("spluttering engine like a car backfiring" etc) seem to point in that direction as well.

Incidentally, it's almost impossible that a pilot incapacitation (heart attack, stroke, etc) could have cause this event. It takes positive inputs to shut down the power to the rotors. A pilot suffering (e.g.) a massive heart attack would either let go of all the control levers or possibly slump onto them. Either way, that wouldn't cause a shut down of the rotors - the helicopter would have flown into the ground under powered flight in such a scenario.
 
Rolfe said:
I would like to say, out of the question, but after the Moorgate tube disaster, one can't really rule anything out a priori.

Newsnicht in 20 minutes, might get a bit more information.

Rolfe.
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Do they do you a separate Scotch-flavour Newsnight, or do you have to look at Paxman's scruffy beard with the rest of us?
 
We split off at eleven. Paxman takes great delight in crashing the changeover so that he seems to be rudely cut off in mid-flow.

I didn't hear anything earth-shattering - they're wittering on about minimum pricing for alcohol sales now.

Oh - Clutha report starting now.

Rolfe.
 
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Interviewed a retired "expert" who mostly just agreed that we don't really know anything yet.

Rolfe.
 
Rolfe said:
Interviewed a retired "expert" who mostly just agreed that we don't really know anything yet.

Rolfe.
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Well, caution must of course be exercised. But I think there are things that we can now say are unlikely as causes (without ruling them out altogether).

I would say (and I personally know some people who have worked for the AAIB, and one who still does - though not on this case) that the AAIB's investigations have so far pretty much ruled out any sort of catastrophic failure of the engine, gearbox, final drive or shaft. By "catastrophic" failure, I mean the type of total failure that, in and of itself, would cause total loss of rotational power to the rotors.

The AAIB will have been able to examine (and possibly even test by this stage) the engine and gearbox, from which it is usually easy to tell whether or not there has been any major mechanical failure. There is of course the possibility that there was a partial mechanical failure or malfunction in the engine(s) or any of the drivetrain components, but not the sort of failure that would cause a helicopter to fall out of the sky with no powered flight.

Again, I'd come back to the supposition that the only two real possibilities for the crash now are catastrophic failure of fuel supply or some sort of pilot input. The AAIB have determined that neither rotor was under power at the time of impact. In the absence of engine or gearbox failure, this only points to those two possibilities: either there was some sort of manual disengagement of power to the two rotor sets, or both engines more-or-less-simultaneously stopped delivering rotational power. And if it's the latter, then by far the most likely causal factor is sudden fuel starvation to the engines. A possible other cause might be a near-total sudden loss of airflow to the engines, which is to say a massive bird strike. However, there would be clear evidence of any such strike within the engines, plus there's every change that the pilot would have been able to restart the engines in time. So I would provisionally rule out a bird strike.

Of course it bears repeating that all this is no more than informed speculation. But I certainly think that today's news from the AAIB has significantly narrowed down the possible list of causes of this fatal crash. Let's hope that the AAIB is in a position to release further information within the next couple of weeks - it should not take them too long to run full tests on the engines, the fuel management systems, and all the electrics and hydraulics.
 
FADEC malfunction is a possible root cause that I am seeing kicked about, but it only answers part of the question, since there are two engines and thus two FADECs. If one craps out, and given the power sharing circuitry dual engine helicopters tend to have, what did that malfunction do to the signals going to the other engine? My experiences with such things is a few decades old and not on EC machines, but I do know there can be some strange anomalies as the electrons move about between sub systems. But, against this whole line of thought is the fact that EC-135 is a mature system. I'd offer that with the hours it has flown, EC and the operators and sub system vendors have worked out most such bugs by now.

Given the AAIB's latest summary, something run amok with one of the FADEC's is a "could be." There may be some trace evidence from the engine history recorders, or similar hardware, that could give the investigators some clues. But that leaves me with "but it's a twin ...single engine recoveries are something that is trained for. If one FADEC goes wrong, fly the good engine home. "

That line of inquiry does not satisfy.

Seen a few other ideas tossed out, but taking an aircraft a few minutes from final landing at the base, having flown about a 1.7 hour mission, and following the initial estimations that you've got a cessation of drive to the rotors followed by the rotors drooping to Nr that won't sustain flight, and apparently not permit an autorotational (hence controlled) descent ... leaves a compound emergency/malfunction as a possibility ... with all the pieces still to be removed from the puzzle box.

More than one thing went wrong. That's as far as I can get with the info to date.

Again, the AAIB have their work cut out for them.

As to fuel: what they drained out was enough to keep flying if the fuel system sub components were working as usual. That much I understand from people who fly that model of helicopter.

The witness reports of noise / backfire / sparks from the helicopter may point to a compressor stall ... but that is likely to have left some evidence that the forensic investigation will uncover. Not sure how far into the components they've been able to get.
 
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LondonJohn said:
failure of fuel supply or some sort of pilot input.
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Or one led to the other, in either direction. To me this seems most plausible. If the information I have read regarding the fuel system for this particular model is correct....unusable fuel can be very lsmall quantity...or more than the fuel that was recovered depending on whether the aircraft is in a hover or in forward flight and which pumps are off or on.

The popping noise that several heard is also quite telling and could point to fuel. The loss of rotor speed also could fall in line with fuel...although may include the possibility of error by the pilot.

The above is speculation of course. Although I feel it is more and more probable fuel will play a central role in this one way or another.

As with many aviation accidents...it may be several small cascading events that lead to the accident.
 
383LQ4SS said:
The popping noise that several heard is also quite telling and could point to fuel.
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How so?
Loss of fuel usually means the engine winds down. Compressor stall is usually from an engine trying to run and having air flow, not fuel flow, get interrupted which then leads to fuel / air mix going wrong with resulting symptoms you note there. Failure in fuel metering? Usually manifested in an overspeed, though depending on how or where ... yeah, could result in a compressor stall.
The loss of rotor speed also could fall in line with fuel...although may include the possibility of error by the pilot.
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Loss of Nr from engine no longer providing drive means a pilot didn't react as they are trained: lower collective when Nr droops.

So who was flying the plane?
As with many aviation accidents...it may be several small cascading events that lead to the accident.
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Indeed.
 
Darth Rotor said:
How so?
Loss of fuel usually means the engine winds down. Compressor stall is usually from an engine trying to run and having air flow, not fuel flow, get interrupted which then leads to fuel / air mix going wrong with resulting symptoms you note there. Failure in fuel metering? Usually manifested in an overspeed, though depending on how or where ... yeah, could result in a compressor stall.

Loss of Nr from engine no longer providing drive means a pilot didn't react as they are trained: lower collective when Nr droops.

So who was flying the plane?


Indeed.
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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:

Of course there are many other things that can cause popping or banging noises. Heck..I once had a call from tower saying that the Coast Guard personnel thought they heard some banging from our helo as we were doing touch and go's in Hawaii. They operated Aérospatiale Dauphin and we were in a tandem rotor CH-46...lol. We landed and checked everything out and of course found nothing. Their Dauphin sounds silky smooth and our Sea knight typically sounds like a washing machine on spin mode with an unbalanced load.:o

So average witness statements have to be weighted appropriately of course.

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.

The other thing I realized is that Police helo's that operate over crowded cities have it quite tough when emergencies happen. I would much rather be over the jungle or desert any day.
 
Bond Air Services has suspended flights of its EC 135 helicopter - the same model which crashed on to The Clutha bar in Glasgow, killing nine people.

The grounding comes after a fault was discovered on an EC 135 operated by Bond for the North West Air Ambulance.

All Bond's 22 UK air ambulances and police helicopters are affected.

The aircraft's manufacturer, Eurocopter, said it was not telling other operators of the EC 135 to ground their helicopters.
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http://www.bbc.co.uk/news/uk-scotland-glasgow-west-25353001
 
Could be a maintanence problem unique to that operator..
A mechanic/technician doing something wrong several times.
One of the L-1011s had all three motors shutdown in flight due to a mechanic's improper servicing of the oil filters.
The RAT supplied hydraulic power to the controls, and one engine was restarted to get the plane down safely.
 
Fuel gauge issue which may not be linked to the Clutha crash. In fact it doesn't seem to have an obvious link.
And the Clutha death toll has risen to ten.
 
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