PPRuNe Forums

PPRuNe Forums (https://www.pprune.org/)
-   Rumours & News (https://www.pprune.org/rumours-news-13/)
-   -   BA038 (B777) Thread (https://www.pprune.org/rumours-news/340666-ba038-b777-thread.html)

Swedish Steve 14th August 2009 20:03

We are barking up the wrong tree here.
The water in aircraft fuel tanks is not introduced by refuelling. It is normal when refuelling to take a sample from the bowser/dispenser. The apparatus to do this is built into the truck. This sample is then tested for density and water. This is normal, and done all the time by refuellers. A small sample of the supplied fuel is drawn through a Shell water detector capsule by a syringe. In all my years refuelling aircraft, I have never seen any water detected.

The water in fuel tanks comes from the air in the tank. If the empty tank is full of humid air, the water will settle into the fuel on refuelling. Some aircraft have complicated systems to remove this water. The best I have seen was on the Tristar. A system of jet pumps and small bore pipes sucked up all the water from the bottom corners of the tanks and sent it into the engine feed system. I spent many happy hours cleaning these jet pumps as they became clogged, usually with bits of sealant from the tanks. Even the B777 has a much simpler system of water scavenge to accomplish this. Obviously on this occasion it didn't work.
Also the tanks are sumped by technicians about every day by draining liquid from the bottom sumps of the tanks. This is difficult in the winter as the water will freeze, but is done when practical. I have done this many times, and rarely seen more than a few cc's of water in the drain bottle.

cockney steve 15th August 2009 09:50

As many Japanese car owners will have noted, there is a relatively cheap and simple way to eliminate atmospheric pollution.

Automotive Brake Fluid is extremely hygroscopic, a feature which dramatically lowers it's boiling -point and helps the system rust from the inside.

The wiley orientals put an inverted soft rubber "top-hat" under the filler-cap....as the fluid level drops, so does the membrane (retaining -cap is vented, as normal.

Now, Concorde's tanks were lined with a flexible-rubber in it's latter days , so it's not an insurmountable problem materials-wise.

I appreciate there are srructural members, baffles and the like to contend with which may necessitate separate "compartment" bags which could be pinked by a standardised coupling. A metal outer-tank would still be required for mechanical strength and containment of the "bladders".....as fuel is removed, the bladder collapses...any water condensatewould collect on the OUTSIDE of the fuel-bladder and inside the structural retaining tank which would need draining, of course.

This doesn't come without a weight penalty, but IMHO there's a major safety benefit (as anyone who'se experienced brake-failure will testify :} )



Going back to the fuel spill-return /heat-exchanger idea,- coaxial pipework with the warmed return on the outside would also insulate the supply from ambient temperature. any failure of the inner-pipe would merely "short-circuit" the rerturn /flow path A leak in the return would be no different to what would obtain in the present layout. again, a safety benefit at minimal penalty.

Appreciated that I may well be talking poppycock,but just sometimes, the bystander sees something the participants miss.

sooty655 15th August 2009 19:30


Originally Posted by Swedish Steve
The water in aircraft fuel tanks is not introduced by refuelling. It is normal when refuelling to take a sample from the bowser/dispenser. The apparatus to do this is built into the truck. This sample is then tested for density and water. This is normal, and done all the time by refuellers. A small sample of the supplied fuel is drawn through a Shell water detector capsule by a syringe. In all my years refuelling aircraft, I have never seen any water detected.


Originally Posted by Lemain
Looking at the condensate due to humid air, let us consider the worst case of an empty tank full of saturated air at 30C. The mass of water could be up to 30g per cubic metre (i.e. 30cc water or six teaspoons-full per cubic metre). I am not surprised that you seldom find much water in the sumps.


Originally Posted by Rightbase
IIRC BA038 was pretty well water and ice free before starting the 2-way trip to Beijing and back.

Can't all be right, guys. :confused:

At the risk of stating the obvious, either

1) There was water in the uploaded fuel, or

2) The amount of water condensed from the incoming air was much greater than calculated, or

3) The aircraft hadn't been sumped adequately before the flight, or

4) It wasn't ice in the fuel system which brought down BA038.

Sooty

Rightbase 16th August 2009 00:36

Sorry, Sooty
 
It isn't a case of either-or. It is and-and-and.

My (amateur) analysis of water source candidates based on information available is:
3Kg Max dissolved moisture at Beijing uplift (AIB all tanks)
2Kg Max entrained moisture at Beijing uplift (AIB all tanks)
Max adiabatic ingestion into centre tank (single air mass assumed):
0.4Kg descent to Beijing 0 degrees @ surface = 4.8 mg/litre
1.2Kg descent to LHR 15 degrees @ surface = 12.8mg/litre
Max adiabatic ingestion into main tanks (total for both tanks)
0.2Kg Beijing
0.7Kg LHR
Plus an unknown amount caused by centre tank fuel purge jet pumps sucking air for two and a bit hours after the tank is emptied (this may be the AIB's 0.14ltr (=0.14Kg) drawn in through the fuel tank vent system)
Plus any remnants of dissolved and entrained LHR uplift
Plus trapped water that cannot get to the sumps (0.35 litres total found in the main tanks at the earlier inspection - AIB) which is almost certainly totally innocuous.

The total is something like 8 litres max.

About a quarter of the uplift would start in the centre tank, so the centre tank could contribute some 2 litres or more. The centre tank is IMHO significant because instead of sucking air the fuel purge pumps will inject its water into the cold main tanks once the centre tank warms up above freezing.

phil gollin 16th August 2009 16:03

Re. water amounts/tests

IF you had bothered to look at the thread, and the second interim report you will see that the tests are on "out of spec" fuel (90 ppm ????) and were still faked/forced to get some sort of problem.

The fuel in China has been stated to have been in spec (or "exceeded" spec) (70 ppm).

The second interim report goes into the samples taken in remaining tank (40 ppm ???????) and likely fuel conditions.

It is no good setting new hares running if they have already been shot.

See, for instance, post 2476,

Pinkman 16th August 2009 20:03

Smilin_Ed

Phil Gollin's post effectively answers your question - I would have basically said the same.

Pinkman

ChristiaanJ 16th August 2009 20:18

We're now at 130 pages with really nothing new on the subject.

I'm "unsubscribing".... keeps down my incoming e-mail.

Maybe when there's something really new, there will be another thread.

CJ

Basil 30th August 2009 15:37

Captain Peter Burkill
 
made his final flight for BA yesterday.

BA hero Peter Burkill takes off - mirror.co.uk


fire trucks sprayed it with water - a traditional send-off for retiring pilots.
I don't think so - unless they're on fire.

Apologies for the source :O
Pity they couldn't find a library pic of a 777.

keel beam 31st August 2009 10:25

On fire? Just for clarity.

overstress 31st August 2009 21:53

Basil, you're mistaken, this does happen, I've witnessed it a few times.... how can you make such statements without knowledge of the facts...

Algy 1st September 2009 08:04

But not always...
 
I landed at Singapore in a BA 744 and on shutdown the FO came on the PA and announced that the captain had just that minute told him that it was his (the captain's) final flight as he was retiring and would be returning to London as pax. Perhaps we'd like to congratulate him. Which we did.

I supose there's an argument that that's the professional, albeit boring, way to do it. A bit like the RAF not allowing studes to make their final sortie on a course solo.

M.Mouse 1st September 2009 11:42


Were talking about two fire trucks forming an arch of water that falls just like rain. Aircraft fly in rain all the time, it's not unprofessional.
Not unprofessional but totally naff in my book.

bizdev 1st September 2009 11:48

Send Off
 
I was a passenger on a United B777 flight from LHR to Chicago a couple of years ago when, on landing at Chicago, the Captain came on the PA to advise passengers not to be alarmed at the sight of fire tenders spraying an arc over the aircraft as it passed - we were not on fire! It was a 'traditional' send off for the Captains last flight. A nice touch I thought.:)

JW411 1st September 2009 14:17

They tried to do this to me on my last commercial flight but the OAT was well below zero and the aircraft was on a quick turnround! Fortunately the firemen were persuaded to desist and common sense prevailed.

manrow 1st September 2009 20:47

This thread originally was all about an aircraft incident not about retiring captains?

:ugh:

Basil 1st September 2009 20:52

It is NOT a traditional send off.
It MAY be done but I know many retired pilots who were not washed out, most because they didn't make a big deal of their retirement.

overstress,

I've witnessed it a few times
Quite.

manrow,
this refers to the pilot commanding the 777 on the day of the accident.
Edited to add: and probably more interesting than some of the rubbish spouted on this thread.

misd-agin 1st September 2009 21:01

Basil,

It's a common send off in the U.S.

Anothet 'touch' in the U.S. is to get a transponder code that has a special significance to the retiring pilot.

Basil 1st September 2009 21:07

misd-agin,
Thank you for the info re the US.
This was, of course, at a UK airport and is not at all a common sight here.

Glamgirl 1st September 2009 21:53

Normally I wouldn't post here, but just wanted to make you all aware that the "send off" had nothing to do with Captain Pete. He knew nothing about it until it happened.

I'll run back to where I belong now...

Gg

Khaosai 3rd September 2009 15:07

Hi,

dont know Peter but would like to wish him well in the future, wherever that may take him.

Rgds.


All times are GMT. The time now is 16:58.


Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.