Fuel Leak Drills - Multi-engine aircraft.

[Cornish Jack]

This is to anyone operating ME aircraft (assuming multi fuel tank installation with crossfeed).
Could you check your Crew Drills for fuel leaks and subsequent engine shutdown/failure.
In particular, what information is offered to determine source of leak and what would be the effect of a leak UPSTREAM of the LP cock. From what I can find in our 744 QRH, it would be POSSIBLE (not necessarily probable) that following the drills, without thinking it through, COULD lead to considerable fuel loss.
I would appreciate any input from anyone else out there. :confused:

[tired]

Have just completed my 6 monthly sweat in the box, strangely enough our current sim. detail includes a fuel leak drill. (It was set up 3 months ago, so someone in the Training Dept must have a crystal ball - wonder if it can forecast the stock market?? :))

Anyway, back to the question - A340 drills basically say "if you are SURE it's from an engine,(because you see it leaking through the window) then shut the engine down; but if you don't know where it's leaking, then close all the crossfeeds." This seems fairly sensible to me - it should minimise the potential loss of fuel until you can sort it out or get to a runway.

The drill then goes on to say, descend to the gravity feed altitude and switch the fuel pumps off because this will minimise the potential loss of fuel - if an engine subsequently flames out while there's still fuel in it's tank it's probably because the leak is in that engine, or it's feed line - (fuel pressure without the pumps being insufficient to service the engine and the leak simultaneously.) Once you've secured the engine you've probably solved the problem.

This all seems to make sense to me, any comments?

[Cornish Jack]

Thank you Tired.
It sounds as though the 340 takes a more realistic view of the possibilities than the rather 'bald' approach on the 744. My concern, obviously, stems from the recent incident which left me with the feeling that there could be problems induced by just strictly following the printed Checklist.
I was wondering if there would be a case for including operation of the Fire Switch as part of the engine shut-down following a suspected or actual fuel leak? That way, the spar valve would be closed and there should then be no further associated fuel problems. How does that sit with you?

[tired]

On the 340 (and I assume the 330 is the same, though I've never flown it so I don't know) if you shut the engine down with the master switch you shut both the fuel cocks (HP and LP), which would achieve what you're trying to do in the case of a fuel leak. If you use the Fire Button you shut off all the other services as well - hydraulics, air etc. - you also shut off the bleed air from the adjacent engine - very sensible if the engine IS on fire, but in other cases it might leave you with a few extra, unwanted problems. So I think on the 'Bus it's probably better not to use the Fire button unless you need to. Don't know how that ties up with the 744?

BTW - the Airbus QRH is not quite as clear as I made it above, so don't feel bad about yours! I was lucky enough to have it explained to me in words of one syllable by a kindly Training Captain - once he'd pointed it out, it became obvious what Airbus was trying to say, but at first reading it was quite obscure, at least to me :)

[gas path]

CJ
The spar valve or L.P cock is actually in the tank so a fuel leak upstream would be of little consequence except you might find a rapidly increasing fuel qty. in the affected tank. When you shut down an engine by the start lever or the fire switch the spar valve is signalled closed anyway.

[scanscanscan]

Tired...
The airbus drills are designed to be clear, logical and easily understood by very tired two man crews at 3.30am during a full scale emergency situation in bad weather.
Or so my mum thinks.

[Cornish Jack]

Gas Path
Whoops!! :o Many thanks!! The ubiquitous 'They' are right.... Age is a degenerative disease. :D
I was trying to look at the possibilities of a leak from a part of the system where opening the crossfeed would direct ALL the fuel into the leak. The mental picture was wrong - back to the drawing board!!

[tired]

scan*3 - what a pity your mum doesn't work for Airbus........ ;)