Qantas 747-400 loses electric power...

[Saitek]

Boy, that was very close to a big disaster.

http://www.bangkokpost.com/topstories/t ... ?id=124968

[C]

Boy, that was very close to a big disaster.

http://www.bangkokpost.com/topstories/t ... ?id=124968

Mmm, may have been reported with a "non-aviation" reporter slant. Electrics in such a large aircraft tend not to just fail in one go, but gradually trip out (unless you suffered complete engine failure!). The report mentioned how if it had been out to sea it could have been disasterous, but then again, as soon as they'd lost the second (and certainly third) generator, they'd probably have been looking for the nearest suitable airfield. And even with total electrical failure it isn't going to fall out of the sky - it may be a little more fun to fly, but it wouldn't just crash.

[Ashar]

In case of an electrical failure, is it not the job of the RAT to provide a little power for the aircraft? :-?

[Splinter562]

To quote the article:

A Qantas engineer familiar with the the 747-400's electrical systems said the failure was unheard of.

Given the failure described in the article, what they've said is absolutely correct. In a "normal" failure situation you would expect one or two engine-driven generators to go down and the remaining generators to pick up the load. In the event of a quadruple engine-driven generator failure, you could descend to an appropriate altitude and get power off of the dual APUs. And the chances of having a quadruple engine-driven generator failure and a dual APU generator failure are so remotely slim that is almost impossible without having some other sort of catastrophic failure involved. Something else must have happened to cause all power generation systems to fail, maybe a failed relay or a grounded wire in exactly the wrong place.

The consequences of a total electrical failure of a 747 in the transatlantic is pretty serious. You are going to loose all of your navigation information as well as your radio and transponder. At that point you could pretty much consider yourself Charles Lindbergh in a 747 with just an altimeter, airspeed indicator, magnetic compass, and over 300 people's lives hang in the balance.

If you want to have some fun in the sim, go ahead and try a total power system failure in a heavy for yourself. You'll be missing out on half the fun though because if the aircraft only has electrically driven trim, you're stuck with what you got all the way to landing. I've you're really feeling brave, get up to FL350 and try failing all engines and the electrical system and try to glide it into an airport.

EDIT: The RAT is used to provide hydraulic pressure for the primary flight controls in the event that all engines (or engine driven hydraulic pumps) fail.

[Papa9571]

It is now being reported that water somehow entered the generators generator control unit and caused the problem.

http://www.smh.com.au/news/travel/power ... 18579.html

[Papa9571]

Now it seems the problem may have shown up at Heathrow before the flight began.

http://www.theage.com.au/news/travel/pa ... 96122.html

[expat]

In case of an electrical failure, is it not the job of the RAT to provide a little power for the aircraft? :-?

The 747 does not have a RAT (neither does the 737)
Not that much of a biggy really and even if it happened at 36000 feet over the Atlantic at night, descend to 25000 feet, start the APU's, declare your self and do what you are trained for. If as in this case, only standby power was available and it was used up to the point of system shutdowns, then engines would still operate. They have their own generators for electric power (different from the ones in question and different controller) and in the cockpit you have manual altitude and airspeed indicators, compass etc. Not forgetting emergency torches. If it had all gone so wrong to that point, they would have already informed ATC before the radios went dead, ATC would have cleared them to land well before and monitored them on radar to keep all other aircraft away. As usual a paper selling story.
When the first A380 has its first incident in a similar vane, the tabloids will be foaming at the mouth to get a story out.

Matt  


Matt

[Papa9571]

A cracked drip tray under the first class galley was the culprit. Funny how something so simple can cause such a big problem.

[expat]

A cracked drip tray under the first class galley was the culprit. Funny how something so simple can cause such a big problem.

Yes something  both Boeing and Air Bus are good at.............putting electrical equipment compartments directly under galleys.

Matt

[Saitek]

A cracked drip tray under the first class galley was the culprit. Funny how something so simple can cause such a big problem.

Really? Any links for the read?

[Papa9571]

Here it is.....

http://www.smh.com.au/news/travel/qanta ... 42706.html