Qantas B744 Total electrical failure?

[PJ2]

Brian;

Would the QAR, FDR or CVR record information following the loss of power, or lose a number of parameters?

Again, I haven't flown the B744, but I strongly suspect that all three recorders would stop recording at the moment of normal AC/DC system power failure. There may be some aspects of the CVR/DFDR which may be powered by the DC Standby busses but given the dire need to conserve all power on batteries, I doubt it very much. There is approximately six crucial minutes of data missing from Swissair 111 precisely because of this power loss, (including the CVR).

[NSEU]

"Standby power from the batteries provides electrical power to the standby compass/standby attitude director/standby ASI, for a minimum of 30 minutes."

An almost full list can be found on the D&G forum. The pilots were certainly not relying on tiny clockwork instruments under Standby Power. The Captain would have had all his glass instruments running and would also have had the Left FMC and Left MCDU at his disposal. The Upper EICAS would also be working (I imagine with all engine parameters available in a compressed format). However, I praise them for keeping their cool.

I don't have details handy for the ISFD's fitted to QF's 747-400ER's, but I believe it is more towards 3 hours of battery life (and provides attitude information as well as airspeed and altitude. The airplane in BKK was not this type however.

Rgds.
NSEU

[PAXboy]

The full list is in a post in the large D&G thread, from Going Boing and it makes you weak at the knees just to read:

The aircraft (OJM) was on descent into BKK (late afternoon with fine weather conditions) when the cabin crew reported a major water leak in the first class galley area (turned out to be caused by blocked drains). Shortly after that the engine driven generators dropped offline accompanied by a huge number of related EICAS messages. Power was available only to the Captains PFD, ND and standby Attitude indicator. At the time that this happened, the leading edge flaps had already been deployed due to the 210 knot limit in the STAR for BKK.

The crew started working through the checklists for the more important EICAS messages but after realising that they were not going to get the generators back on line the captain elected to get the aircraft on the ground ASAP before they ran out of battery power. Alt gear/flap extension, no anti-skid, no autobrakes, no thrust reverser were some of the issues that they dealt with in a very short time frame and then landed safely. On the ground, outflow valves had to be manually opened using remaining DC power to depressurise prior to opening the doors. A flap asymmetry occured when they tried to retract the flaps (believed to be due to elec control of leading edge flaps).

[Self Loading Freight]

This is one of those incidents to wheel out when someone starts banging on about pilotless passenger flights, isn't it...

R

[skiesfull]

NSEU -I have now found the notes about the ISFD. It has power for 150 mins following power loss to the main electrics. Only 744's built after 2003 and fitted with LCD's would have an ISFD. Don't know if it's a retro-fit available.

[sky9]

The incident has completely screwed up the fail safe design philosophy of the 747 (and other Boeing aircraft?). If a blocked drain can knock out the GCU and put the aircraft on standby power, its suitability for operating long over-water flights is brought into question.

There will have to be some careful thinking about the location and protection of the GCU's. Back to the drawing board.

[Joetom]

Well done to the all the crew.

Seems strange that a fluid leak should cause problems for all 4 elec systems. aircraft systems tend to be placed in various locations so a local problem will not effect the others.

Sound more like 1 or 2 elec systems were effected and the sudden increase in the load of the other two systems kicked them off line.

One point that has crossed my mind is the 400 started flying in the late 80's and fitted with sutiable elec power systems of 60 KVA per engine I think, however over the years the extra elec demand put on these systems has increased (IFE is the big one) so when 2 elec systems drop off line very close together in time, the remaining 2 systems may not like the sudden increase in load.

I guess these aircraft have been tested to loose 2 elec systems at the same time, but if the remaining 2 systems have any issues and with the bigger elec loads now fitted it was just a matter of time until this event occured.

I wonder if Mr Boeing will now allow the APU to be started in the air, seems like it may be a good idea!

[spannersatcx]

(turned out to be caused by blocked drains).

So the old redwine and milk being poured down galley drains almost caused a disaster, when will they ever learn.

[NSEU]

"NSEU -I have now found the notes about the ISFD. It has power for 150 mins following power loss to the main electrics. Only 744's built after 2003 and fitted with LCD's would have an ISFD. "

Thanks, skiesful.. two and a half hours seems to be a lot better than 30mins to an hour If you can't make it to an airport within this time, you really are having a bad day.

The generator control units and bus control units are laterally spread along the top rack of the MEC. Seems like a fair compromise to me. The central location means you don't have miles of extra wiring and cooling ducts... and engineers don't need a GPS to find the units. If you're looking for total design insanity, look at aircraft with large oxygen bottles located under the cockpit floor :P

The 747-400 has a synchronous bus, which means that all the generators are feeding the same busses, but there are lots and lots of safeguards built into this system (e.g differential current protection). This really is a freakish event. I'd really like to see how the Airbus would handle a torrent of water washing over the electrical control system.. or for that matter, flight control computers (as someone has already asked).... or a combination of both!

Back to a previous question ...The 744's FDR and CVR run off the main busses, so these would not have been much help after their respective busses went offline.

Re extra loads... That's what the loadshedding systems are for. However, this would be controlled by the very units that were being inundated.

Rgds.
NSEU

P.S. Latest rumour is that more than the aforementioned (replaced) units were waterlogged.

[Starbear]

Ah NSEU, I see you have just posted a very interesting description as I toiled with my effort. Thank you.

There is no doubt that the final report on this will make very interesting reading and hopefully contain some important lessons. I am very keen to know the exact sequence of failures and QRH actions and yes there is some very good discussion on the D&G thread.

What most intrigues me is not that a flood of water could knock out ALL the GCUs (there will be at least 4 of them and not one as implied). All could be taken out if on the same rack as described but I am really surprised that QRH actions could not recovery any of them at all (is this in fact known yet?)

When a generator trips off-line via its GCU, it may be possible to reset the GCU if the cause of the trip was of transient nature such as a temporary overload causing a underspeed scenario. A short circuit may cause further problems but really should only lead to an individual generator (or bus)being isolated. So to lose all 4 (did the aircrfaft despatch fully serviceable?) seems to suggest a continuous torrent of water or several bus bars permanently shorted to earth.

Faulty drains and drip trays have caused problems before but not quite so dramatically as this 747. I recall an L1011 where water leaking from the first class toilet area dripped onto an electronic box conveniently located immediately below that toilet. This box (the ILCB I think) contained a bunch of circuit cards which controlled every single indicator and warning/caution light on the aeroplane and so in spectacular sequence proceeded to illumiinate everyone of them and also caused the switch flowbars to pulse in rythmn.

Not intended as a thread hijack but just to recall that Murphy will always win given half a chance.

[NSEU]

I don't think we will ever know what happened to the electrical system in this case... just too complex to analyse.

A few complexities....

The GCU's (Generaror Control Unit) have a quite a degree of autonomy and control both BTB's (Bus Tie Breakers) and GCB's, but are in many ways co-ordinated by the Bus Power Control Units. e.g. With all busses parelleled, the #1 Bus Power Control Unit provides the master frequency reference (400Hz). I recall the BCUs also control Autoland Bus Isolation.

There are two Bus Power Control Units (BCU's), however, one seems to be the slave of the other one (e.g. to close the Split System Breaker, the #1 BCU sends a signal the the #2 BCU and the #2 BCU closes the SSB. With the #1 BCU underwater, who knows what tricks it would be playing on the electrical system

Rgds.
NSEU

[Brian Abraham]

Thanks PJ2 - so if it happened on a dark and stormy night threading the ITCZ mid Pacific and ended in the water we would be none the wiser, perhaps. Even assuming the recorders were recovered.

[PAXboy]

sky9

If a blocked drain can knock out the GCU and put the aircraft on standby power, its suitability for operating long over-water flights is brought into question.

Yes and No.

There was NOT a single event that caused this. Drains were blocked and (it is reported) drip trays over the racks of electrical equipment were faulty. There may have been more 'holes' in the cheese but it was not just one.

Also, if this is the first such failure in more than 37 years of the 747 series, then it is a truly exceptional failure. The problem, it appears, is poor maintenance. Drains not cleared, drip trays not checked and people trying to get an a/c back on the line without the proper checks. In other words, Human Factors driven, it seems, by commercial pressures. Let us see what Boeing and the regulatory authorities say.

[sevenstrokeroll]

USAToday had an article about this incident. It reports it as well as we have seen on this thread.

What does come to mind is this: cost.

You pay 100's of millions to buy a big beautiful plane...yet you skimp on what appears to be minor maintenance (drains).

This problem will only get worse as more planes are sent to cheap maintenance facilities to save money...in the short run.

I've seen so many brand new expensive cars on the side of the road...spent money on the car...couldn't spend 40 bucks for an oil change.

you get the picture!?

[mono]

It doesn't matter HOW good the maintenance is. If the cabin crew insist on pouring milk, tea leaves, coffee grinds, wine, bar seals, pens, and various other cabin detritus down the galley drains then they WILL get blocked and possibly cause a similar problem.

On the plus side, galley downpours like this usually only occur during take-off or approach due to the a/c pitch speed changes so it is unlikely (though not I guess impossible) that it would have occured in cruise.

[ChristiaanJ]

mono,
Wot? No recycling bins?
Coffee grinds and tea leaves make great compost.

More seriously... not being cabin crew.... I would have expected drains for the liquid and semi-liquid rubbish (such as coffee grinds) and some sort of rubbish chute + container, or bags, for the solid stuff.
I'm too naive, no doubt?

No time to sort? In which case, why not have the same gadget in the drains that every American household seems to have and that chops anything dropped into the drain into small bits?

[4potflyer]

I have seem many a waste disposal unit put out of action by coffee grounds. Maybe a sieve that fits over the plug hole would work better but cleaning it out would be a problem.

Perhaps better water protection on the electronics is a better investment ;-).

[PJ2]

sevenstrokeroll;

What does come to mind is this: cost.
You pay 100's of millions to buy a big beautiful plane...yet you skimp on what appears to be minor maintenance (drains).
This problem will only get worse as more planes are sent to cheap maintenance facilities to save money...in the short run.
I've seen so many brand new expensive cars on the side of the road...spent money on the car...couldn't spend 40 bucks for an oil change.
you get the picture!?

Yes, and I think "the picture" is extremely important for our industry.

I would like to respond to your post and by virtue of that, to the posts of many here on this thread who have been making similar observations regarding the fundamentals of the airline industry worldwide which this incident seems for many to be highlighting (although, because the investigation is not out, is not necessarily "proving").

I responded to interesting comments made by a poster on the D&G thread, (kalavo, Post #134, "http://www.pprune.org/forums/showthr...=307552&page=7", and offer those comments to those on this thread.

kalavo;

Where I work we would get our arses kicked if we left that situation untouched. There is a change management process, and peer review to make sure we're not going from bad to worse, but anyone who left something so significant without doing anything about it, would more than likely be asked not to come Monday.

[said with mock sarcasm....], Clearly you're not in the airline business then... Such reviews might come up with changes that cost money, you know.

Now, if management isn't taking these problems as seriously as they should be, then that is an issue CASA should be addressing and you have means of contacting the regulator to ensure that happens.

Unfortunately, easier said than done given resource levels at some regulating authorities. Internal safety management is what "SMS" is all about, so airlines under SMS are "self-regulating" with a drop-in audit by the regulator to see if the books and documentation are ok.

In the race to the bottom to control cost and increase shareholder profit, any deviance that can be normalized without result will be explored and with today's management mentality which doesn't know it's in the aviation business, likely taken.

The anger you readily recognized on this thread is a bunch of guys/gals who know aviation and who know this pattern and it's effects upon flight safety viscerally and not just the effects on pocketbooks industrially.

As someone else posted, a job-well-done in aviation which is both actually comprehended and perhaps even grudgingly respected by management goes a lot farther to maintaining a safe and profitable operation than any number in the bank accounts does. Numbers in the bank account sometimes even follow such mild apprehensions of the value of employees' skills and experience. Short-term thinking may work in pushing stock of department stores etc, but it doesn't work in airlines - it is the wrong metric because the technique's shelf-life is as short as the next accident.

The anger you see here boils from the one cauldron aviators know only too well and is seen in elementary posters in all flying schools...that;

Aviation in itself is not inherently dangerous. But to an even greater degree than the sea, it is terribly unforgiving of any carelessness, incapacity or neglect.

— Captain A. G. Lamplugh, British Aviation Insurance Group, London. Circa early 1930's.

The story unfolding on this and the other thread in the R&N section is that airline employees the world over are seeing the same thing: the race to the bottom in cutting costs, the unbridled power of the shareholder to control management decisions despite the business they're investing in, and the resulting pressure to maximize profit at all cost. One way or another, airline managements will come to learn the lessons which taught you the processes you describe in your post - that they would get their arses kicked if they permitted such processes to compromise the integrity of the work at hand. Sadly for airlines, such processes are increasingly unwelcome at corporate safety meetings. Unfortunately for aviation and the airline business, the people who are good at kicking employees and suppliers for being the expensive liabilities they are while cutting notches in their cost-control rifle-stock, are invited to return Monday morning and those who take, and otherwise suggest the side of caution (which always equals increased costs), are increasingly unwelcome or at best, tolerated as boardroom anachronisms. In other words, the exact opposite of what you describe often takes place - nobody wants to hear about mistakes.

Intelligent, informed, comprehending cost control can be done safely. It takes experience, expertise, good data and a sense of aviation to do so wisely. It also takes listening to employees which today is about the last thing a management experiences as employees the world over have turned so strongly against management that there is virtually no communication. You cannot beat down wages to eight bucks an hour, make pilots pay for training, or dump employees' futures off in court bankruptcies forever. The effects of poorly-implemented LCCs are now being seen, first with employees but sooner or later, likely in the accident rate.

Airline employees know these truths. That is the anger you are seeing expressed on this and other threads - perhaps mildly misdirected at times and not perfectly grammatical, but real nonetheless.

The key to resolving these fundamental issues lies in two areas - the separation of hegemonies from realities and the return to governance by aviators or those who know aviation and not mere MBAs who couldn't describe an aileron from a coffee-maker but who know the price of both and the wages of the guy installing them, both of which are automatically too much.

Managements' seeming incapacity to comprehend why employees are angry means we can expect that despite the new year's optimism in re the numbers, the accident rate will rise over the coming years. And, no one will know why because there is absolutely no courage to look inside this business and why commercial priorities are pushing out the fundamentals. The last one to do so was Virgil Moshansky of Canada and he has expressed great concerns over SMS, or the "de-regulation of safety".

The employees of airlines around the world who are at the pointy end and in the engine compartments are the canaries in the mine. Their cautions, sometimes forcefully put and perhaps pushed out in all directions because they know that the friend as well as the enemy of aviation is profit, are being set aside by those who know nothing about aviation and who don't know that they don't know.

There is so much more to this than any one post or even thread can delineate...

[Cider30]

Landing

So lets say we get this 747 across the pond, find a nice VMC area lit up by a full moon, what effects would this complete elec failure have on landing.

If not able to isolate the generators and get 1 online and out of standby power, will

Flaps extend,
anti-skid work,
Trim work,
Speed brakes work,
Reversers work,

Feel free to add to the list. Lots of mechanical, hydraulic driven **** needs electricity for actuation, so how to land a 747 wihtout any electric power checklist suggestions

Cider30

[NSEU]

"If not able to isolate the generators and get 1 online and out of standby power, will..."

"Flaps extend," NO (not without Battery or Standby Power... this supplies power to the Power Supply Electronics Units which power the Flap Control Units. Alternate Flaps use electrics, too)
"anti-skid work," NO
"Trim work," NO
"Speed brakes work," YES, manually.
"Reversers work," NO.

This is assuming we are talking about a 747-400, not an earlier 747.

Assuming your trim was not too far out of whack... a successful landing would not be beyond the realms of possibility. The aircraft might be a bit wobbly in cruise with the Yaw Dampers not working... and the aileron lockout unlocked.

Instead of the usual call "Is there a doctor on board?"... it will be "Is there an aircraft engineer on board? It would require a lot of imagination, though (especially without tools).

Rgds.
NSEU