MEL Generation
 

Each engine has two generators, so if you depart with one engine generator MEL'd, you have three other engine generators available. Should you lose the APU battery and APU, you still have three engine generators available to provide power. Even if you should lose the engine with two good generators and the APU, you still have one engine generator available and it can carry the load.

If this is the case why would you need the APU if an Engine Generator is inoperative, if you think One Engine Electrical system can provide all the power for 2 Electrically driven Air conditioning Units, 2 Center Electrical Hydraulic Pumps, All the Fuel Pumps, IFE, Electric Deicing, the list goes on...
The 777 & 767 cannot meet all the electrical loads with one Engine generator and that has pneumatic Air conditioning, Air Driven Pump, Pneumatic deicing...
Is the 787 safe to fly in its current format and with the Band aid fix?
No way!

Of course there would be some electrical load shedding if the aircraft dispatched with one generator u/s THEN the APU battery failed and THEN the main battery failed and THEN there was an engine failure on the engine with the two good generators, not the one with the generator U/S.

Even in this extremely unlikely scenarion where 4 unrelated failures have somehow occurred, there is STILL a 235 Vac variable frequency generator working and a Ram air turbine, or shall we say "yeah but what if they failed too?"

Sir, I admire your stout attempts to defend the indefensible.

Shall we say "Cascading failure"? Or perhaps "Avalanche effect"

It's already established that a faulty battery can "lock-in" and create mayhem with the theoretical redundancy-layers. Add to that, the deafening silence about the pyrotechnic control-panels.......

THE EMPEROR'S GOT NO CLOTHES!!!!!

Old Engineer: #1624
Not quite sure what you mean by "remain connected" in this context, but
from what I understand, the battery must be fast charged after apu start,
so that it is ready for another start in flight at any time.

The only way that this can be done, apu not running, is to power the charger from
the generator bus. The battery / charger must be connected to do this...

-

Old Engineer
From what I have read, the APU Controller is powered by the APU battery only. So should the battery fail, that powers down the APU controller and the APU. I understand this is the scenario that happened with JL8 at BOS (once the APU battery failed, the APU controller and APU shut down).

I've been told this is a standard Boeing Commercial Airplanes design philosophy and is not unique to the 787. Boeing employees I have spoken with have explicitly said this is how the 777's APU operates, for example.

What worries me about this a/c is its lack of true redundancy. Its all electric so whilst there is plenty of back up generating power, at some stage in a failure situation busbars have to be linked to get a system to work. Hence the potential for contagion. A/c to date have had effectively three separate power souces hydraulic electric pneumatic, these can back each other up through power transfer units etc, which do not lead to contamination. One only has to think of the tremendous care that say New Yorks power system has been arranged and yet a simple failure can lead to its total shutdown.

The APU runs for long periods unmonitored, from the flt deck. During turnrounds etc. If it catches fire then clearly it has to shut itself down and fire its fire bottles. On all a/c I have flown this is standard practice. To power the fire bottles in such a situation pwr is needed, from the battery, If the battery fails the unit shuts itself down as it can not carry out this vital action.

Understand the necessity for the APU (and indeed for any system) to have monitoring in case of problems but couldn't this be served by incorporating a small PMG in the APU, thus making it independent of any external power requirements?

The word Melodrama comes to mind.

From your previous posts you appear to have inside information. If what you are saying is true then in a few weeks time when it appears the 787 will be flying again lots of people's lives will be in serious danger. Therefore the responsible thing for you to do would be to make a, well reasoned cause and effect type augument based on sound engineering principles.

Todays Senate SubCommittee hearing on Aviation safety

Hearings - U.S. Senate Committee on Commerce, Science, & Transportation

Click on the persons name for their testimony.

I listened to the first two hours and the 787 never came up beyond the opening statements by the FAA and NTSB heads.

The Senators were mostly carping to the FAA head about cuts to contract staff in towers at airports in their state due to the Sequester and then later offered their opinions that current rules banning the use of personal electronics on planes was stupid.

Yahoo! News UK & Ireland - Latest World News & UK News Headlines

Looks like no ETOPS beyond 180 for a while...

@cool guys..... No inside info, just old,cynical and been round the block more than a few times.

I have spent time with arrogant, concieted ,smartassed "Suits" who are full of crapand their own self-importance.

The fact that there was not a major aerial conflagration is sheer luck and casts grave doubts about just how a certificate of airworthiness could be issued for something, which rapidly proved itself unable to meet those standards.

Eh? What? politics, big business and unemployment?....they have NO place in air-safety decisions.

Until Honest, open, full and frank disclosure is made, I treat any utterance by a Boeing mouthpiece, with the contempt it deserves.

These PR- types are paid a handsome wage for their ability to manipulate,distort, obfuscate and sidetrack any uncomfortable truths.

The deafening silences, half-truths (omission of any dialogue regarding control-panel issues, failure to honour their commitment to the authorities when consulting with Yuasa)....Get the picture?

This "management" has shafted one of the best Aircraft-builders in the world
you can be bloody sure they won't walk away with empty pockets.



THAT's what upsets me! Many far-better qualified engineers than I, have pointed -out major deficiencies in the design and build of fundamental safety-attributes of this aircraft. Surely you can understand the frustrations of this group, seeing the apparent cover-up, deceit and sharp-practices that are going on?

If it waddles like a Duck, quacks like a duck......

You REALLY expect us to believe it's not?

Another bombastic windbag with nothing but a keyboard and too much time on their hand.

This thread is full of indisputable evidence such as,

"it's been done on here already"
"it's already been established"
"experts on here have already demonstrated"

Erm no it hasn't. All there is on here is a load of views and theories from random people who can post what they want as long as they have a way of accessing the internet.

It's not a forum of experts, it's just a place for people, anybody at all, to talk about stuff to do with aviation.

There seems to be people that think that because something is posted online it somehow has an increased likely hood of being correct.

back to the battery, I was a little surprised to figure out that the containment was per cell. That means 50 fasteners for each cell times 8 cells.

I havent seen if there is another box that this all fits in, but I am sure that is interesting.

Is this for the new, improved battery? If so can you provide a link to the description you are working from? I have been unable to find anything more recent than the original Boeing graphics of the redesigned battery and more helpful photos of the overall containment box.

This is what I saw...the containment box at the upper right looks to be per cell...it is much smaller than the original battery box at the left...

http://cdn0.sbnation.com/entry_photo...sure_large.jpg

No. I think it's just camera perspective.

What impact will these changes have on Maintenance times ?