nhs, please look at the post mentioned above and others in the same page.

Please understand that I agree 100% with the what M.Mouse, a Pilot, says: it would have been superhumane to land succesfully in these conditions, in other words even if it would have been theoretically possible, nobody can expect an unprepared crew to accomplish.

Anyway for the last time, if anyone wants to believe that it was a manual landing, OK with me, but it was not.

I have read the latest AAIB report.

Water content of the fuel seems to have been established from fuel samples after the crash.

According to the AAIB and other reports, most of the remaining fuel was spilled and only a few tons remained.
Somebody, many hundreds of posts ago, suggested that, with water being heavier than fuel, under the circumstances a lot of water could already have drained from the aircraft by the time the fuel samples were taken.

Question: might there have been a lot more water than quoted in the AAIB report?

CJ

At last ... some official indications on crew actions ...

28 sec before impact thrust levers were partially cycled
16 sec before impact flaps were raised from 30 to 25 (you was correct M.Mouse !)
8 sec before impact FO pushed the control column

At that time AP disconnected, pitch attitude was 14 deg up, anyone to determine the AOA ?

Flight idle fuel flow looks to be around 3000 pph per engine ... surprised that 6 and 5000 pph did not bring the aircraft a bit further ?

Note: Right FF maintained pretty stable at 6000 pph when Left FF reduced from 5 to 4000 pph in the last 15 sec

Boeing is releasing new operating procedures to deal with the BA038 icing threat, according to this newspiece in FlightGlobal.

Interestingly, they seem to concentrate on the "ice blocking heat exchanger" scenario and not the "ice accretion in the pipes" scenario.

Glue Ball,

Increasing AOA to stay on the glide until the stick shaker is activated ( what the autopilot did according to the AAIB report ) is definitely not the way to get the best chance of making it to the runway... It is a fact, simple fly mechanics. Stall speed is certainly not the best gliding speed.

Therefore, considering that the plane missed the runway by a reasonably short distance, it is not a surprise that a pilot WHO KNOWS WHAT IS GOING TO HAPPEN, i.e. that the thrust will never come back, could be able to land the plane on the concrete by immediately taking the right speed, slope, and wing configuration. So, i am pretty confident that the simulation may be quite relevant.

That doesn't mean that the real pilots on the real flight were wrong in their actions, they had no way to guess what was to happen in the next seconds...

And in fact, they saved the day by pushing the stick and reducing flaps as soon as the situation became clear.

Thanks M.Mouse (#1780)
 

Re: my question 1778 http://www.pprune.org/rumours-news/3...ml#post4375609, your answer 1780 http://www.pprune.org/rumours-news/3...ml#post4375780, linking to http://www.pprune.org/rumours-news/3...ml#post4322326

Indeed it does answer my question, M.Mouse. Thanks.

I didn't think of exploiting ground effect to boost lift: the picture of a glider/skydiver landing didn't jump into my mind when imagining their 777 over Hounslow.

If I may ask, how did it work out for you on the `several attempts' prior to using the recipe you posted on the `medal' thread for reaching the threshold in the simulator?

Hi all,

in the report iy says there are three tanks on 777.

Im a 340/330 guy and just wondering if there ain't any outboard tanks inside the wing tanks.

In the 340/330 there is an outboard tank which usually has around 2500 kg of fuel. This fuel is kept near the edge of the wing to help reduce the moment of lift at the wings. The coldest fuel is most of the time in this tank and this tank usually will be used at the end of the flight when all other fuel is used.

My questions for the 777 experts:

1) Is there a small tank like this at the edge of the wing ?

If yes

2) is there a fuel temperature sensor for this tank on the 777 ?

Regards,

Guclu

Respect...
 

An impressive AAIB report which I am sure will reward more study.

For those unhappy that an extremely unlikely event should affect two independent systems within a few seconds of one another - there is a common factor over and above the shared history of those systems. The centre tank which is supposed to be empty, but is still in the loop.

The previous flight is significant because with ground temperatures in Beijing below zero, any ice from the outbound flight would not be scavenged.

The fuel uploaded in Beijing was warm enough to have melted this into droplets; the behaviour of the resulting droplets in terms of their size, accretion rate and so on, in the centre tank of an aircraft at rest in a below zero environment is problematic, but if it froze again before start-up, the water scavenge, and later the fuel scavenge would not get it. It would not start to melt and move from the 'empty' centre tank until the warmer environment of the descent.

So there is the credible possibility that at some time in the descent a melt surge presents ice, wateer and/or slush at the centre tank fuel scavenge points, and is then fed to the main tanks to be refrozen as it makes its way down to the boost pumps .....

If this happens during an unusually prompt arrival at late finals on a cold winters day, another hole lines up.

It would be particularly concerning if a procedural attitude or acceleration change could trigger such an episode which then prompts a temporary fuel restriction episode timed to coincide with a critical procedural need for more power.

Since the AAIB work is continuing, they must believe further recommendations are a possibility.

Snowfalcon2
 

I think the idea is that the ice forms in the pipes and collects on the face of the heat exchanger. The procedures attempt to dislodge the ice before enough builds up to cause a problem. I can see the need to do the powerback and wait(hope) shortly after the pre descent power up!!

Hotel Mode,
Never seen it - guess I stopped flying before you started. Last time I asked Boeing they couldn't help.

Barit 1 said:


I agree with Barit1 here,

The solution to an Hi temp light coming on in the decent (which is not uncommon) for many twin-spooled engines is to push up the power and throw out the boards, because those are fuel-cooled oil systems: the increased fuel flow (higher than idle) cools the oil system and the light goes out. No need to write it up since you just fixed the problem.

The point here being: decent at idle is a high-temp situation; not a freezing situation. I know that sounds backwards, but for most of the seven transport types I flew that is true.

However, the heat exchanger is no doubt regulated by another computer chip on this tripple spooled model. More complexity equals more unreproducible, unpredictable results.

This accident already is shaping up to be another 737-Rudder, 747-center-fuel-tank mystery.

Blaming icing by itself seems unlikely to me. The 747SP flew up to 45,000 feet for 26 hours routinely for thirty years and never had any problems (that I know of.) It even completed a 54 hour flight. KC-135's B-52's and airborne command posts have remained aloft for days without any problems.

Tanimbar said:

I agree Tanibar and others, this is a shocking statement and makes me wonder how other airframes have stayed aloft for over a quarter of a century with no icing problems. Prist type additives? The 747SP (which I merely jumpseated) has nine tanks and surely runs into this problem up in the 40's. But all of the aircraft I mentioned (747SP, B-52, KC-135, 747-EAC-1) were non-FADEC (before engine upgrades) and their safety records were based on direct-link hydro-mechanical designs.

The FADEC is usually the culprit when you are discussing rollbacks. A pilot with a control cable would keep trying to clear the ice out by trial and error. A FADEC goes back to idle and tries to reboot a start sequence.

JMHO's only.

I was happy to see the cavitation marks mystery solved. :ok:

I suppose this blows the electronic/computer glitch theories out of the water finally.

From http://www.pprune.org/3852203-post176.html posted by a handsome fellow I know well.

:8

Interesting report. It's mentioning twice that the CVR worked and nothing much. I'm glad it worked but I guess it could be even more interesting to have some details about its content.

According to the FDR the captain retracted the flaps to 25 at 240 ft resulting in increasing the pitch up attitude while the AP was already pulling on the nose to follow the glide until reaching 14 degres nose up. The AP finaly disconected following the stick shaker when the FO pushed on the stick at 170 ft and around 100 kts.

Usualy retracting flaps in dead stik approach is associated to a nose down command and speed increase, not the contrary.

Differences between Trent 800 and GE90
 

One of the reasons that interim procedures published by Boeing apply only to Trent 800 powered 777s could be differences in design between the two engines. (See Boeing 777 FCOM)


Fuel System, Flow Path:
Trent 800:
1st Stage Engine Driven Fuel Pump
Fuel/Oil Heat Exchanger (FOHE)
Fuel Filter
2nd Stage Engine Driven Fuel Pump
Fuel Metering Unit (FMU)

GE90
1st Stage Engine Driven Fuel Pump
2nd Stage Engine Driven Fuel Pump
FOHE
Fuel Filter
FMU

This means that on GE90 engines the fuel has already gone through the second stage (HP) fuel pump before it enters the FOHE, which will cause some rise in temperature



Oil System, Flow Path:
Trent 800:
Oil Pump
HP Oil Filter
Air/Oil Heat Exchanger
FOHE


GE90:
Oil Pump
HP Oil Filter
FOHE
Backup Gen Oil/Oil Heat Exchanger

That means that in Trents the oil has already part of the heat extracted in the air/oil heat exchanger before it makes its way into the FOHE.




No conspiracy theory required after all?

is the 5th report, and still the reason od that reduced fuel flow is unclear.

interesting report anyway but:
1) I was surprised to read that such approach was conducted in Autopilot. It would seams that they had other problems to handle if they decided to perform an auto land.
2) I was surprise by the action (desperate i believe) of the commander reducing the flap setting and continuing to keep the plane in autopilot,
3) I was surprise that the crew failed to anticipate the stick shaker situation (they do not have an Alpha floor protection)
4) I was surprise that the A/P was disconnected only by the F/O that apparently pushed the column into the Eicas (as supposed to do)

since the only possible obstruction was up stream of the HP pump It looks like the B777 needs like a Cessna a hot hair (to the carburator) swith, or some Aspirine in the tanks to reduce the piping cholesterol of this giant plane.

ZAGORFLY

1. They were not performing an "autoland". They were performing an autocoupled approach to disconnect at some point prior to a manual landing. Like probably 99%+ of airline approaches...
2. The Final Flap setting (30 for 777, Full for Airbus etc.) is largely all drag... You describe it as desparate... most would describe it as inspried and almost certainly saved many lives. Training nowadays is almost 100% directed towards using the AP with a problem - not disconnecting it.
3. They did not "fail to anticipate" the stick shaker... they had already selected full thrust many seconds before :ugh:
4. I doubt the SFO "pushed the CC into the EICAS" - nor do I think that is the laid down drill in the QRH/FM :{

IMHO you and many others are wasting your time dissecting what the crew did (or did not do). They did a damn good job, working outside the box, but not excessively so, whilst trying to correctly troubleshoot the problem(s). Assuming you are even a pilot (?) since when do you practice stall recoveries close to the ground AND with zero power... it is not taught in anything (other than a glider?) since it is negative, improbable and inapproriate.

We do train for engine failures, and we do train for stall recoveries (but with power, or at least height).

This inquiry, IMHO, is 99% concentrating on WHAT caused the power failure(s), and preventing future occurances... in the short term by determining the circumstances and avoiding then, and in the longer term by design. I think it unlikely more than a fraction of the final report, and probably none of the formal recommendations, will be on crew actions / extra training to deal with essentially a double engine failure at ~2NM :ooh:

NoD

Ice Ice Baby
 

Captain Big Iron:

Also Concorde comes to mind. I know that the Investigation team is of the very best and the report is extremely thorough. But still, after millions of flights by both 747 and 777 aircraft on these routes in similar conditions, it does seen strange. I suppose that on this particular flight the holes in the Swiss cheese slices just happened to align perfectly?

There have been several other reports of 777 aircraft having engines not respond to commands in situations where ice is not likely to have been an issue. To those familiar with the 777, did these incidents also involve RR Trents and have these incidents been adequately explained?

Fuel Heating
 

I am surprised this has not been more in the forefront of thoughts. I cannot say specifically for the B747SP, but certainly for the "classic" B747 and going back a few more years, the B707, they had dedicated fuel heaters. these were switched on by the flight engineer if he had a Fuel Filter Block warning light. After a set period of time, the fuel heater was switched off.

Looking at the diagrams on this thread, fuel heating is only supplied by the Fuel/Oil heat exchanger.

Just a thought ....

Last 720 ft
 

Just my 2C,

If the AAIB are prepared to go public on a very probable icing issue here, after my 15,00hrs, much of it Ultra Long Haul, albeit on B747s, I will believe them.

The crew actions can be second guessed forever, but after the Schipol freighter double engine failure and loss a few years ago, we tried it (As I'm sure most 747 operators in the world did) in the sim.

Being fully aware of the preliminary reports, doing a briefing, and configuring the sim as best we could to simulate the conditions experienced by the crew, it took me, as a Training Captain, 4 tries to achieve even a marginally survivable result----and this was not at the end of a 15 hour day.

Re a previous post, from my recall, the 747 at F25 required an increase of pitch of about 1.25 degrees above that for F30, but with a significant decrease in power required i.e. drag, so good call there for the flap reduction.

Well done crew.

As an aside, from the later pictures, it would appear that a significant part of the A/C was on the piano keys, so it wasn't really a short landing, just an early touchdown.

I'll get my coat.:D

Question from a non pilot.

When a liquid is compressed, temperature rises. When pressure reduced, temperature falls.

How is the flow of fuel controlled (physically, not logically) ?

Would it be possible for the 'valve' controlling the flow to form a point at which pressure was reduced, thus cooling the fuel even more and maybe causing ice to aggregate?

A small restriction could then, under some circumstances, become self perpetuating

Concorde had the opposite problem in the cruise, its tip probe temperature was the governing factor. Concorde's TAT was high at supersonic speeds. Cold fuel was not an issue.

Not exactly so.

To celebrate the 50th anniversary of Pan Am, flight 50 as it was called flew a route from and to San Francisco that indeed took 54 hours, 7 minutes, and 12 seconds to complete but it was actually comprised of multiple sectors. Stopovers were at London Heathrow, Cape Town International, and Auckland Airports.

Physics
 

Quote:

---

Originally Posted by stickyb

Question from a non pilot.

When a liquid is compressed, temperature rises. When pressure reduced, temperature falls.

How is the flow of fuel controlled (physically, not logically) ?

Would it be possible for the 'valve' controlling the flow to form a point at which pressure was reduced, thus cooling the fuel even more and maybe causing ice to aggregate?

A small restriction could then, under some circumstances, become self perpetuating

---

Quote:

---

Originally Posted by stickyb

---

I think you’ll find you can’t compress a liquid.

I think you will find that you can compress a fluid although the visible effect is minute compared to gas/vapour. Indeed, a compressed fluid is less viscous than one which isn't compressed. That said, the values concerned are so small it is not worthy of any serious discussion.

Posted by ChristiaanJ, ref. post #1782:

Please read the report(s) again.

AAIB interim report G-YMMM, Page 2, second column:
"The aircraft had previously operated a flight on 14 january 2008 from Heathrow to Shanghai, with the return flight arriving on 15 January 2008. The aircraft was on the ground at Heathrow for 20 hours before departure to Beijing on 16 January 2008."

AAIB interim report G-YMMM, Page 13, first and second column:
"G-YMMM was last sumped at Heathrow on 15 January 2008 prior to the flight to beijing. The aircraft had also been sumped at London heathrow whilst on maintenance, on 14 January 2008."

"Prior to the accident the operator had initiated a review of the effectiveness of their [water] sumping programme, . . . . . ., a number of aircraft were checked in a warm hangar where any ice in the fuel tanks would have melted and migrated to the drains. G-YMMM was sumped in this manner on 14 December 2007. The review established that whilst the free water does freeze and could occasionally block the tank drains, there was no evidence of any significant quantities of free water having accumulated in any of the 43 Boeing 777 aircraft."

AAIB Special Bulletin S1/2008, first column, Page 5:
"The aircraft's [G-YMMM] fuel tanks were last checked for water in the fuel on the 15t January 2008, this was prior to it's refuelling for the outboard sector to Beijing."

With the aircraft on the ground for 20 hours and a review programme in place, wouldn't it be logical that sumping on 15 january took place at a time it was estimated that any ice in the tanks had melted before sumping commenced? Especially with the aircraft on the ground for 20 hours and temperatures well above freezing (as records of those dates indicate) and sumping taking place before refuelling. The interim report does not mention how many hours after arrival from Shanghai water sumping was performed but to my knowledge this is done immediately prior to refuelling? Refuelling probably took place any time after the payload, flight planning and weather for the flight to Beijing were known, so this would have happened perhaps only a few hours (but still on 15 January?) before departure?

If so, and water sumping was done correctly, there would be very little water in the tanks. This, together with sumping on 14 january during maintenance should imply the tanks were virtually free of water as G-YMMM departed to Beijing.


After reading the report several times, although it is very informative, new questions regarding the aircraft systems and engines surfaced for me which i shall digest for a while.

The emphasis is now focussed on ice. 5 liters of water diluted in approx. 100.000 liters of fuel . . . . and a lot of data mining.

I'm sure they will find the facts, the evidence, and the reasons why in the near future. I hope they are not barking up the wrong tree.

The investigation, although very detailed and thorough, gives me the impression of trying to castrate a fly with boxing gloves on :uhoh:

Green-dot

I am pretty sure at the beginning of the BA038 speculation threads, people were talking about the possibility of 100's of litres in not 100's of Kgs of water potentially being present, at least in the centre tank, as the norm? What's changed, or was this gross misinformation?

...and the mass of 1 litre of water is...Doh!:ugh:

What a fascinating interim report - illuminating and in plain English. I would like to highlight a few points which might be good to see addressed (or dismissed) in more detail in due course:

1. Cold soaked main tank fuel from previous sector

Figure 1 seems to indicate that just prior to the uplift of fuel in Beijing the temperature of the 4 tons or so of fuel in the left hand main tank which was left over from the previous sector was -20˚C. Even after the uplift of warmer 5˚C fuel in Beijing the left main tank temperature never appears to rise above -1˚C. If temperature is as relevant as suggested, then a body of fuel from the previous sector remaining at -20˚C seems noteworthy as a possible contributory factor leading to the potential subsistence and continued development of accretions of ice in at least those parts of the main tank fuel system which remained at or below 0˚C.

2. Prolonged fuel scavenge operation

The interim report currently seems relatively silent on a key design feature of the 200ER as compared to certain other Boeings - namely, the relative size of the centre tank and the prolonged operation of the fuel scavenge.

The data (in Figure 1) shows that the remaining 800kg of centre tank fuel to be scavenged once the main tanks contained less than 12.5 tons started a little under 3 hours before landing and was finished within 30 minutes.

Given the apparent ability of each of the two centre tank fuel scavenge pumps in G-YYYM to suction fuel at a rate of some 0.8 tons per hour into each main tank, could there be any unintended consequence (which would normally have no bearing on safe flight absent some of the other contributory factors present that day) as a result of them running “dry” for over 2 hours once the remaining 800 kg was indicated to have been scavenged (and similarly on previous sector)?

After remaining 800 kg of fuel was scavenged, would not the fuel scavenge pump, being a jet pump, scavenge air? What volume of air would be entrained/dissolved into fuel in each main tank over remaining 2.5 hours of flight given powerful nature of scavenge pump? The centre tank is open to the atmosphere so any air sucked out would be immediately replaced. Presumably entrained/dissolved air in main tank fuel would be subsequently released as part of dynamic process given low pressure at height? Could this entrained/dissolved air end up in the fuel manifold and be released in a manner which would cause the potential failure of the suction feed or the override/jettison pump valves to open? As the suction feed in the climb at least seems to have a known failure mode from vapour lock (see previous posts) arguably the interim report’s understandable assumptions as to the location of a restriction might need to be reconsidered slightly if it could be shown that the suction feed might be vapour locked and/or (even more speculatively but for a similar reason to the suction feed) air might not be drawn in from the centre tank. Fuel testing after the event would not be able to establish the existence (or absence I accept!) of any air saturation dynamic and any vapour lock would be long gone. NB: my point is limited to expanding the possible locations of the icing restriction as I note the comments about aeration not being the cause of the cavitation in the HP pump.

As regards the 800 kg remaining shallow layer of fuel in the centre tank, is there any temperature or other information as to potential stratification in the 5 hours or so that it sat in a largely empty, cold still tank after OJ pumps selected OFF? Does the 0.14 max litres of water from condensation reflect turnover (if any) of atmosphere in the centre tank as a result of the operation of the fuel scavenge pumps in the last 3 hours of the flight (or the earlier sector)? Might there be any concentrations of water from accreted ice melting in the later stages of flight? Would slugs of water scavenged from centre tank be more likely to result in any particular form or size of ice crystal more susceptible to accretion when swept into main tanks? If ice had also previously accumulated and not melted on previous sector into Beijing could this be a contributory factor? The AAIB’s comment re unknown fluid dynamics seems spot on and not easily resolved given the complexities of the many different variables (eg Jet A1, ice, temperature, pressure, airframe, geometry, timing etc). Testing showing only 40ppm of water makes explaining the degree of icing sufficient to cause a restriction (sorry two restrictions), but not subsisting in any quantity in the main tank fuel, the mother of all tortuous theories though.

One relatively simple precautionary safety recommendation might be (eg as per certain other Boeings) to require the motive flow to the centre tank fuel scavenge pumps in 200ERs to be cut off after 30/40 minutes of renewed operation. Continued scavenging is unnecessary and might be a necessary contributory factor in lining up the holes in the two swiss cheeses (two cheeses, given must be at least one restriction on each side of the fuel system).

Alternatively, the fuel system test rig should perhaps also attempt to take account of what effect each fuel scavenge pump might have on fuel in the main tanks and the fuel supply system leading out of them?

3. Statistical significance of duplicated restriction in two independent fuel systems

The comment on page 19 of the interim report that "This is the first such event in 6.5 million flight hours and places the failure as being 'remote' as defined in EASA CS 25.1309" perhaps does not do justice to the statistical significance of what happened. While the statement may be correct, it could be seen as overstating the remoteness of the "event" - in particular, given the sharpened awareness from the data-mining that the particular environmental factors relevant to this event have occurred in but a few of those many flight hours and the fact that the current strawman is dependent on there being two separate duplicated events, i.e. one restriction in each independent fuel system, with assumed common contributory factors.

Also, if I may quibble with what may have been unintentionally implied by the word “remote” in the context of EASA CS 25.1309, when is a double engine rollback on a twin engine aircraft at very low altitude over a highly populated area caused by a restriction to the fuel supply to each engine limiting effective supply to about 15% or so of the certified maximum just a “major failure condition” for which “remote” is the relevant test, rather than a “hazardous failure condition” or a “catastrophic failure condition” which have to meet stricter standards? It would seem extraordinary to play down the significance of this demonstrated and duplicated failure condition, even if the improbability of its recurrence is in question.

4. Indications, annunciations and corrective actions

Also in the context of that same EASA CS 25.1309, which states in paragraph (c) (just read it at http://www.aaib.gov.uk/sites/aaib/cm...pendix%20B.pdf) that:

“Information concerning unsafe system operating conditions must be provided to the
crew to enable them to take appropriate corrective action. A warning indication must
be provided if immediate corrective action is required. Systems and controls, including
indications and annunciations must be designed to minimise crew errors, which could
create additional hazards.”

would it not be helpful and practical (and perhaps necessary) to introduce an immediate warning and annunciation of the discrepancy between the Actual EPR and the Commanded EPR as soon as the more normal 2-3 second lag becomes a clear discrepancy as at about second 154[95] (in figure 2), rather than requiring crew to observe the discrepancy and establish if it is “just” a glide slope, autothrottle or other issue – even more so by second 160[95] when both engines are rolling back.

Needless to say, the crew did the most remarkable job – and this seems more apparent as the background unfolds and you look at how little time and room they had to act.

Pardon me if this has already been discussed (I just joined), but glancing through the previous posts as best I could looking for remarks on what the pilots did in the final moments, I couldn't find what I was looking for.

What are the thoughts of those pilots on here about the Captain (I believe it was) REDUCING the flap setting after realizing their problem of maybe not making the runway? Seems to me this aggravated the problem by INCREASING the stall speed, therby requiring the F/O to lower the nose, thereby making it impossible to reach the runway.

A master stroke :ok:
The last stage of flap is almost all drag with little contribution to CL (coefficient of lift) so he immediately got rid of some drag.
The go-around procedure on, e.g., the B747 is - max thrust, flap 20 (jus' like that!) and you don't drop out of the sky but transition instantly to a high energy situation partly by getting rid of drag which has permitted you to keep the engines spooled up just for that eventuality.

1 Kg! Oops :O

The Restriction Was Upstream of the FMV
 

While it might be possible, in this case, the restriction has been shown to be upstream of the HP pump and thus even further upstream of the Fuel Metering Valve.

Green-dot (post #1805),
Many thanks for taking the AAIB report apart more carefully than I did.

However, how effective is sumping? The report quotes no figures, just the conclusion from the review: "there was no evidence of any significant quantities of free water having accumulated..."

And also "If so, and water sumping was done correctly, there would be very little water in the tanks. This, together with sumping on 14 january during maintenance should imply the tanks were virtually free of water as G-YMMM departed to Beijing."

All this is qualitative, not quantitative, which made me wonder whether we were talking about 5 ltrs, 20 ltrs or 100 ltrs being "significant" or "virtually free of water"..

But, going back to the report, the amount of water estimated in the Bejing fuel upload was in the order of 40 ppm (the 5 ltr quoted). The samples taken after the crash were in the same order.
So, for the moment, it looks as if I'm barking up the wrong tree.

Bedankt, Green-dot!

CJ

I sump fuel tanks on aircraft. We drain out about a litre into a clear plastic container, and you might see a globule at the bottom of the bottle, less than 1cc. Sometimes you find nothing. So a decilitre would be significant, and 5 litres cause for an investigation.

I also work in Sweden, we do not sump tanks when the OAT is below zero. Bit silly really, but ice will not come out!!

I don't know if anyone else caught this little gem in the letters page of today's Telegraph;

Letters to the Telegraph

6 September 2008

De-icing aeroplanes

SIR – As a frequent flier with smaller aircraft, I know that it is common knowledge among pilots that condensation builds up in fuel tanks. This water sinks to the bottom of the tank and must be periodically drained to avoid it being drawn into the engine.

One would assume that ice forming in the fuel lines of a big jet (report, September 5) indicates that there’s too much water around and that someone hasn’t been doing their job properly.

Roger West, Appenzell, Switzerland


Why the hell didn't anyone else think of that......:rolleyes:

#1796

Nigel on Draft " Absolutely - the crew were faced with a totally new experience and did their best, magnificently. I'm not sure I would have had the courage to even touch the flaps at that stage, and just thankful that I was never placed in that situation.

To the guy who suggested that draining a thimble full of fuel out of something like a Cessna 152 bears any relation to what might have happened .............. !! Why do I even bother to respond !! :ugh:

I thought it would go down well here....it certainly made me chuckle!! Save us from the experts, eh?

Non-pilot speaking.

Since the new interim report, a couple of people have asked "5 liters of water diluted in approx. 100.000 liters of fuel" and how that could cause the failure.

As I have understood it - that is not what is being suggested. The failure may have occurred because of ice and other particles resulting from the low temperatures. There has been much talk (in PPRuNE) about stratification of the fuel and that a 'dollop' of fuel thickened but not frozen.

Unless I much mistake, no one is saying that a small amount of pure iced water caused the loss of thrust. I sit to be corrected.

Basil -

"The go-around procedure on, e.g., the B747 is - max thrust, flap 20 (jus' like that!) and you don't drop out of the sky but transition instantly to a high energy situation partly by getting rid of drag which has permitted you to keep the engines spooled up just for that eventuality."

Similar with all jet transports. But.....you have the engines spooled up. In this case they were basically without power. Not sure I'd want to touch anything.

PAXboy,

The answer you're after is detailed in the interim report!

B&S