BA Flight lands short of Runway - Page 6

Hom3r · 24-01-2008, 23:13

Were I work I log all the fuel samples taken for all our aircraft, these are sent to lab where they check for biological contamination, this also reports the water contamination.

There is always a small amount.

it is possible that there may have been more than usual.

Xaccers · 25-01-2008, 00:56

Isn't the fuel in airliners used to dissapate heat from the airconditioning etc?

BBKing · 25-01-2008, 10:01

On the SR-71 and IIRC Concorde it was used to cool the aircraft structure, but that was a rather extreme application. Given that it's -blah degrees outside it would be rather surprising.

jkat · 25-01-2008, 13:52

my bet is that its computer/software related, its happened before and they may have quadruple systems etc but they all have the same software.

http://www.cbc.ca/canada/calgary/sto...g.html?ref=rss

http://blogs.law.harvard.edu/philg/2...s-taketh-away/

Xaccers · 25-01-2008, 15:24

Quote:

Originally Posted by BBKing

On the SR-71 and IIRC Concorde it was used to cool the aircraft structure, but that was a rather extreme application. Given that it's -blah degrees outside it would be rather surprising.

I seem to recal a 747 that exploded into a fireball shortly after take off.
If I remember correctly, it's central fuel tanks (used to dissipate heat form the A/C and other systems) were very low, with most of the fuel in the wings.
Sat on the taxiway waiting for clearence (Clarence) on a hot day, the fuel in the central tanks started to vapourise, not much of a problem, even with sparks from one of the electrical systems (maybe even the fuel guage - it's been a while since I saw the program on it), the mix of air and vapour wasn't right for combustion.
However, as the plane rotated, air was sucked out, the mix hit that magic ratio and bang.

Ah here it is, TWA 800 http://en.wikipedia.org/wiki/TWA_Flight_800
If other airliners use the same system, then after a long flight, the fuel is likely to be too warm from the heat dissipation for any water in it to freeze, wouldn't it? I thought water in the fuel was mainly an issue at the start of the flight where the ice has formed before the plane has started?

BBKing · 25-01-2008, 16:36

TWA800 was going up in July, not coming down in January, of course. It was a particularly cold day last week, too.

Xaccers · 25-01-2008, 17:02

Quote:

Originally Posted by BBKing

TWA800 was going up in July, not coming down in January, of course. It was a particularly cold day last week, too.

Exactly, so if on a hot day it was able to produce enough heat to cause an explosion (through an electrical spark in the vapour produced by the heat), then is it unreasonable to think that even on a cold day, the heat dissapated to the fuel would be enough to keep the fuel frost free?
Aren't you more likely to get frost on the fuselage before the fuel tanks?
Was it cold enough for them to require the wing deicers to be active?

SMHarman · 25-01-2008, 17:53

Quote:

Originally Posted by jkat

my bet is that its computer/software related, its happened before and they may have quadruple systems etc but they all have the same software.

http://www.cbc.ca/canada/calgary/sto...g.html?ref=rss

http://blogs.law.harvard.edu/philg/2...s-taketh-away/

Don't know whether it makes a difference but these are RR engines and that was GE90 engines.

BBKing · 25-01-2008, 18:01

TWA800 was caused by ignition of fuel vapour heated in an tank above the aircon units, so would naturally be hotter there - the centre tank on a 777 is apparently empty at the end of the flight, so both engines would be fed from the wings. These would be the cold bit, not being near any of the sources of heat in the fuselage.

Engine de-ice is apparently automatic, but remember icing is a function of meteorology, not temperature. There are certain bands of the atmosphere where it's more likely, which tend to be where turboprops hang out*, hence the highish accident rate of those machines to ice (I've witnessed this in summer on a hop over the Gulf of Thailand which was a worry). Up at 777 level the air's actually dry, so can't form ice. It is jolly cold though.

* http://aviation-safety.net/database/...?id=19940225-1

Uncle Peter · 25-01-2008, 19:11

The software issue theory has been debated on several aviation related forums over the past few days. You can just imagine it:

"An application error has occurred and an application error log is being generated. Please assume crash positions"

Seriously though: if this is the case do you trust a piece of software or an entirely mechanical linkage?

BBKing · 25-01-2008, 19:49

Apparently the 777 systems use ADA. ADA is named after Lord Byron's daughter, as I'm sure you know.

**Hugh** · 26-01-2008, 00:33

Quote:

Originally Posted by BBKing

Apparently the 777 systems use ADA. ADA is named after Lord Byron's daughter, as I'm sure you know.

Try reading "The Difference Engine" by William Gibson and Bruce Sterling - she has a high-profile part in this, an alternate history (steampunk)of the Victorian Age.

Uncle Peter · 26-01-2008, 00:52

Quote:

Originally Posted by BBKing

Apparently the 777 systems use ADA. ADA is named after Lord Byron's daughter, as I'm sure you know.

As is a good proportion of the software on board our Trident submarines. Shelter is already built, no worries.

Hom3r · 26-01-2008, 01:05

Quote:

Originally Posted by Xaccers

Isn't the fuel in airliners used to dissapate heat from the airconditioning etc?

No the fuel does have some type of heater, but it is completely seperate from the AC

BBKing · 26-01-2008, 12:22

Quote:

Try reading "The Difference Engine" by William Gibson and Bruce Sterling - she has a high-profile part in this, an alternate history (steampunk)of the Victorian Age.

Quite, most people* now know Ada Lovelace as Babbage's colleague, but I only found out the other day that she was Byron's daughter.

* Who know anything about British technological history, that is.