"What would your considerations be and what would you do to get this thing on the ground."
I'll leave these sort of things to the real experts
I'm not a pilot, but I've been in the aviation industry long enough to have
some understanding of the problems that pilots face... including the fact that the buck stops with them.... with radio comms dead (or limited by line-of-sight), there is no one out there to help you... That's why I can't stress enough having a good understanding of the basics of flying and airplane operation.
The artificial horizon is a key element in flying the aircraft straight and level. Pilots are taught at a young age not to fly solely by the seat of their pants (i.e using their human senses of sight, balance, etc). Imagine what would have happened if the QF crew was over the Antarctic, lost their artificial horizon and experienced the whiteout effect that led to the destruction of the Air New Zealand DC10 many years ago. Also, as someone mentioned, without electric power, the windows are going to start fogging/icing up with lack of window heat... so you really can't rely on an outside view).
Re the newspaper article...
"A fault with galley drip trays found on a number of Qantas planes may be a problem for ageing Boeing 747s around the world."
I think some of the newspapers have gone a little overboard with the "ageing" aspect. Replacing new aircraft for old is one way of fixing a problem, but Japan Airlines is a good example of what you can do if you throw enough money at your existing old fleet. Their planes are immaculate and, apart from the IFE systems, hardly anything goes wrong with them (ok, so they crashed one 747 into a mountain... but this is another good example of cumulative errors leading to one big one (including problems not envisaged by the designers)). However, accidents and incidents often lead to better airplane design..... albeit at cost to human life.
Qantas, too, is still flying around at least one Classic 747, which is testament to their old system of maintenance and a good basic airplane design. The 747-400's are much younger than this and still have many years of productive life ahead of them. I wouldn't write them off just yet
"Again for arguments sake, lets say fuel is not a limiting factor, so by some form of navigation (pax mobile GPS or star navigation) we get ourself overhead a well lit up airport, good horizon, hell lets even say the sun came up."
I have no doubt about the abilities of pilots to land with basic piloting skills. Fancy electronics are just there to add a greater level of safety. Yes, there have been accidents resulting from optical illusions when visibility is limited, but 747 captains are not "newbies"... they have been around for a long time and know what to look out for.. and CRM allowing, there will be at least one or two people there to help them out.
"Any ideas on how the battery relay-control units works."
Yes (I think).... It depends on what you mean by this. The Battery/Standby Power system is designed around simple electrical relays. In some cases, the coils of these relays receive power from the main busses. If power is lost to these coils, they relax and new circuits are formed using different relay contacts (allowing the (normally) two ship batteries to power "Static Inverters" to generate AC power for vital airplane systems. It is all relatively low power stuff... You're not going to power flap drive motors or run hydraulic motors with this kind of system.
The complex side of the 744 electrical system, however, is main AC/DC bus control. Although a lot of it is configured by simple (heavy duty) relays, there are a number of electronic boxes in the system... GCU's, AGCU's, BCU's, etc. One news article claimed that a single GCU caused the problem, but it seems unlikely. I do know of one situation where one faulty generator during engine startup can cause the electrical system to play up, but more likely it would be the #1 BCU causing the problem in flight. This essentially controls what power goes on the busses by listening to the other boxes, then sending control signals to them. These other boxes then control the power relays. There is a #2 BCU, but it's more of a "slave" than a backup.
Re gear extension without electrics and cutting holes in thick metal paneling... Sounds like a suicide mission to me.... Alternate extension, like normal extension, is a careful co-ordinated affair (to stop the gear doors interfering with the extension of the undercarriage). You really would have to know what you were doing (PA announcement: "Are there four suicidal Boeing undercarriage designers on board please?"). I think the better bet in this situation would be an avionics engineer in the equipment centre with a few rolls of paper towels
BTW, 744 brakes are still controlled the old way.. cables/levers/hydraulics... not that they would do you any good with the wheels still up.
Anyway... I'm starting to put (even) myself to sleep here...
(and it's my day off).
Best wishes.
NSEU