Interesting. This passage caught my eye:

"then you will start to hear strange noises as the combustion becomes unstable in the engine. You will hear a low rumble as parts of the ejector nozzles become too lean to burn."

Various news reports have eye witnesses reporting odd engine noises ("roaring" and "rumbling")...

Oldlae,

Yeah - Guess that's the point grebllaw123d was making. So, I suppose we can assume that the 200ER has not been fitted with the fuel scavenge system design changes that the Service Bulletin is addressing.

Compressor Inlet Guide Vanes
 

The AAIB report says that the compressor inlet guide vanes responded properly to the demand for more power.

....which loaded the compressors more, without the required F/F increase....

Wilyflyer
See the AAIB report that shows that whilst the fire handles were pulled the LP valves did not close....the crew shut down procedures has now been modified...

SpannersatKL
..Yes,but the engines should have been unable to run if the HP cocks were closed by the fire drill , thus still a little niggle about not much fuel should have been leaking if the engines really continued to run on the ground ,(which I doubt)
..But a bigger niggle as to was there evidence was to show the CWTs were really as dry as they should have been by then; in order to disprove any ice block misbehaviour of the CWT scavenge systems?

SeldomFixit

:confused:

even I can't read between the lines when there are no lines posted as a reference to your post:(

Post #160
 

With all due respect, "what's Old is New again." Noises on approach, human factors, stall avoidance, etc. 108 knots with an AOA at that value, is Scary. That Aircraft is not to be stalled, period. (Notwithstanding nonsense replies from bug smasher pilots.) Fuel exhaustion is still on the table, but so is information starvation. This thread is on life support.

Oh by the way,am I correct in thinking David Learmont said in one of the initial reports that the Crew experienced a slight Power Surge problem when they came off the Lam hold????This has not been mentioned in any of the threads I have read,or is a figment of my imagination?

err, wasn't GB flying a BA777 too??

Think u'll find it was good old Vmca on approach, long flight tired crew. Engine No2 failed (check the pics) Crew went heads in, didn't spot speed decay till below Vmca, ie, cannot go around!! must trade height for speed.
The lads did a good job because every body walked away, however couldn't be a great landing because unable to use the aircraft again.

Basically there are no "new" aircraft accidents, just a swiss cheese that when the holes in training, hardware, automatics and Humans line up we get an incident...

Electromagnet Interference
 

Everyone keeps forgetting that the original report by the AAIB says that the fuel metering valves opened in response to the Autothrottle and the crew's movement of the power levers. This means that the engines should have accelerated but instead, they hung up at just above idle. This clearly indicates a lack of sufficient fuel at the fuel metering valves. The real question is why?
[/COLOR]

DingerX
How about anywhere between Hounslow and the crash site!

http://i52.photobucket.com/albums/g1...d/Hounslow.jpg

Or
Within 2 miles of the crash site....anywhere in this picture!

http://i52.photobucket.com/albums/g1...esid/27L-1.jpg

Or
Anywhere east of 27L threshold with the aircraft below 10,560'!

http://i52.photobucket.com/albums/g1...oesid/east.jpg

Or if you want a road map, how about an autoroute route from Downing Street to Heathrow.
Notice, if you will, how the A4 dips nicely south towards the approach path!

http://i52.photobucket.com/albums/g1.../autoroute.jpg

Why are so many posts hostile to the idea of electronic interference?
The AAIB have not ruled this out in fact they don't seem to know what caused the accident.
It could be electronic, it could be that contaminated fuel got to both engines within 7 seconds ( or rather fuel didn't get to..).
Incidentally Both lifts in the Control Tower failed at exactly the moment of the incident. This may not be relevant, on the other hand it may well be. Was the accident caused by fuel,was it a burst of RF, was it Gordon Brown, was it onboard cellphones/laptops????
None of us here know the cause.
The AAIB are not saying, so all bets are on until they tell us what happened.

Because many of us have worked in electronics for years. We intuitively understand antenna theory, the inverse square law and the incredible difficulty of transmitting significant amounts of electrical energy through air.

This tool is interesting.The last time I looked I think the day of the accident had been sanitised.
http://lhr.webtrak-lochard.com/template/index.html

It certainly is, tubby. Thanks for the heads up. Shame about 17 Jan though.

airsound

With respect to all with a profession in aviation, regardless of background, intuition does not always win it from the facts.

I personally had to replace main fuel shutoff valves in engine feed systems (back in the 1980s) because intuition and inverse square laws did not prevent them from closing in an unscheduled manner then. The valves were redesigned and the wiring was provided with an improved electrical connector. And guess what, EMI filter modules were added between the connector and fuel shutoff valve.

I won't go into specific details here, not about what i wrote above nor specific T7 details, not that it matters much because i have noticed that a thread posted by me regarding a GENERAL explanation of the EMI phenomenon yesterday has been removed without the decency of the "puppet-masters" on this forum to explain to me as to why!!! And it has not been the first time with regards to BA038. That makes me wonder.


Regards,
Green-dot :oh:

I believe that was an on going problem throughout the day and NOT coincident with the accident.

Means nothing unless you know that the fault was caused by *radiated* EMI rather than conducted.

The AAIB bulletin stated that the fuel control system was working, the open spar valves were blamed on a faulty shut-down procedure, so it is unlikely that all the RF and the PM's ECM affected the elecrics. So it is obvious innit, all the RF and ECM made the fuel boil thus sending fuel vapour to the engines, causing cavitation and lack of thrust.:)

I did hear that recently an ADIRU fault on a bmi A320 was positively fixed by changing an oven in the forward galley. If the cause was some kind of interference then it could have come from the most unlikely sources.

Why the Fuss
 

Re: Gordon Brown? If his motorcade/Aircraft/Jaguar had anything to do with the incident, (HIGHLY unlikely), it was inadvertent, sloppy, witless. This isn't to say that if the PM was not present or even tangentially involved, that something like what is being discussed couldn't have happened any other way. There seem to be two camps; Brown's retinue downed the flight, or nothing like it happened or could have happened. In the middle is enough room to drive a twelve tonne lorry. Jammer, MW, hostile elements; there is room for all manner of conspiracy, why stop at Brown or Vapor Lock? Curiouser and curiouser. The only changes I've noticed is a minor change in fueling protocol by two yank Legacies, if there were something that could affect the Fleet, it would be common knowledge. Right, AAIB?

OK. I'll bite.
 

Don't fly 'planes or design them. Good at Physics though.

One cause, two possibilities, one result.

Cause. The fuel got too cold and separated to constituent parts. One or more of which didn't like pumps.

Possibilities. Either there was a software warning that was ignored; or there was not a software warning and fuel temperature was therefore not known to the crew.

Result. Engines didn't do the expected.

If I'm wrong I'll buy a personal title. If I'm right I'll buy a personal title.

boguing,
Am I to understand you would be in agreement with my more detailed hypothesis in post #589, page 30?

pls88x

Certainly on the temperature.

Gradient, possibly a factor earlier in the flight although I'd expect that the smallest amount of turbulence would mix the fuel in a part full tank later in the trip. So even if the gradient 'hid' the true temp, the true figure would have been measured after a slosh or two.

My point is that the fuel temp was not spotted, either by the software or the crew.

Real World.

Nobody knows what happened.

So, why haven't all aircraft with this fitout and engine been grounded?

Vapour lock= OutaGas
 

Boguing.
....I dont think mixing is guaranteed by smooth flight sloshing .In a seperate discipline we are warned not to rely on it to mix oil and petrol for 2 strokes.
.
...Now Mr Physics, tell us how much the boiling (gassing) point of hydrocarbon liquids goes down if its freezing(waxing) point has been Orientally cunningly reduced from -47 to -57 ?....Would it be as low as say +10 or +11 centigrade ?
...The same discipline warns us of the Vapour lock problems with usage of winter road fuel above around 7000ft.

Does the in flight fuel temp indicate prominently all the time ?(Seperate from TAT leading edge temp) or is there just a warning show at a value that has been preset according to the crews understanding of the specification of the uplifted fuel?

On the upper EICAS screen in the lower right hand corner the fuel temperature is displayed below the fuel quantity indication. TAT is displayed in the top right corner. Display is always on.

Fuel freeze point is entered manually on the PERF INIT page of the FMC. In BA it defaults to -40°C but is overwritten as appropriate. This figure is used by the aeroplane systems to generate the FUEL TEMP LOW warning should the fuel temperature reach withing 3°C of the entered value.

Vapour Pressure
 

wilyflier:

I have the greatest of respect for the quality of the postings in this thread, let's see if this one is vaguely up to scratch.

It's the Vapour Pressure of the mixture that's changing with sinoadditives and it's that that drives any change in Boiling Point, a pedantic point but one that's crucial in this "vapour lock = outa gas" hypothesis.

Stick out neck time.

Fuel stratification and subsequent cavitation did get my vote - it fits the evidence beautifully , but ....... we ain't heard a thing from AAIB.

The hypothesis is eminently testable and (i) I would be amazed if they hadn't had a go at it already and (ii) if the numbers stacked up in a repeatable way and the model "worked" (iii) we'd have heard by now.

I know, call me naive. Fire away.

CW

Vapor Pressure
 

Chris, this is a popular theory, though it brings up unfortunate implications. (See posts #261 and #602). Fuel Exhaustion is "ostensibly" ruled out, Fuel Starvation has been obliquely addressed, Engine Response is on the Record, Fuel contamination has gotten little buzz. (Notwithstanding the public disclosure of Fuel "testing" absent conclusion as to causation or even postulate). The Fuel "tests" were left unaddressed, and the public does what it always does, "assume" that means the Fuel is cleared. Not so. Everything points to Fuel issues, storage, transit, pumping, temperature, Engine response, etc. even quality. My fear is that the longer the investigative authority takes to update, the more it will overemphasize the ultimate outcome of the investigation. (I hope "Sinoadditve" does not become a new word in the Dictionary, for many reasons.)

Vapour Pressure (2)
 

airfoilmod

I've read every post on this thread but had forgotten 261 and 602. I blame being born in the 40s plus Scotch .......:ok:

I absolutely agree with you, fuel fits best. My caveats obviously obscured that central point.

But but it's very straightforward to do mass spec et al, n times on fuel samples so........... it's back to either my naivity that no news means they've found zip or ........we're looking at something more sinister over possible (temporary?) information suppression.

Yes I know AAIB needs no political clearance etc ad nauseum, if however we don't get a damaging fuel report until after the Olympics we may want to revise that view.

From naive to cynic in one bound!:D

........... and my apologies for "Sinoadditives", I liked it at the time.

CW

4greens
 

I agree with 4 Greens. It's an ETOPS aircraft too. Has it been restricted?

On what basis?

Concorde had an, arguable, design fault which could have led to another catastrophe. When the reason for the BAW38 accident is known a decision can be made.

If the worldwide fleet is grounded or restricted now what reasons would be given? If no cause of the accident is found then would those 600+ aircraft remain grounded?

Groundings are temporary restrictions against the original issue type certificate while it is being brought into compliance with the original specification.

From what I have read there is no varriance identified against the type certificate. For all we know this could be purely an operational problem and nothing wrong with the design.

If you support grounding, then just how far do you go? All recently certified aircraft from all manufacturers? Or do you feel there is supportable evidence to limit it to one manufacturer?, one aircraft type?, one model year?, one or two line numbers? or one operator's fleet?

When all is said and done what corrective action will place this large piece of capital ownership back into service in what time frame?

Certainly any of you can play a ouija board and decide to ground yourselves from flying anytime you choose, but I prefer to abide by a process of a rational approach.

There *is* what appears to be a new interim bulletin on the AIB site - but my Adobe reader hangs when 95% of the .pdf has downloaded and freezes my comfuser so I don't know if it's "new" or one of the "old" bulletins. Anyone read it?

wilsr

The only report I can see which refers to this accident is the 'old' report S1/2008 issued in Feb.

DL

Approx how much time is required to cause the cavitation damage within the pumps that is experienced here.

I would assume that it would take a long long time; much more than a few hours.
.

Pumps Still Serviceable
 

Regardless of how long it took to produce the observed damage, the report says the pumps are still serviceable.

This is just a factual outline
 

The cavitation issue may never have been known if this accident never happened. Although it was not causative, we all must agree that it was unexpected. Perhaps several hundred lives were just saved twenty years from now as a result of this incident. The problem with cavitation is kind of like the difference between a styrofoam cup and a glass. The cavitation can cause the liquid (in this case fuel) to become aerated.

The other issue with cavitation relates to debris. The cavities (no matter how small) can not form unless something is lost or disintegrated. While the fuel flow was not impeded, the combination of the aeration and potential debris from the cavitation may have had some impact.

RR will know the cavitation history from examination of the Trent engines previously returned to them for repair/inspection/overhaul over the years.

Secondly, it is now 2 months since G-MMMY undershot, the AAIB are obliged to issue a report after 30 days which they have done, but are they obliged to issue a report every 30 days?