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US FAA To Impose Special Conditions On Boeing 787  
User currently offlineParapente From United Kingdom, joined Mar 2006, 1548 posts, RR: 10
Posted (6 years 5 months 5 days 9 hours ago) and read 5564 times:

Article on headlines on Flight International.

I am assuming that Boeing has already forsaw this and built in the required back up sources of power into the aircraft from the origonal design onwards. (ie that it could decend from cruising altitude to land without power as the FAA have stated.)Yes?

27 replies: All unread, showing first 25:
 
User currently offlineBlueShamu330s From UK - England, joined Sep 2001, 2866 posts, RR: 25
Reply 1, posted (6 years 5 months 5 days 9 hours ago) and read 5411 times:

http://www.flightglobal.com/articles...-on-boeing-787-electric-power.html

Shamu



So I drive a 4x4. So what?! Tax the a$$ off me for it...oh, you already have... :-(
User currently offlineSmokeyrosco From Ireland, joined Dec 2005, 2112 posts, RR: 13
Reply 2, posted (6 years 5 months 5 days 8 hours ago) and read 5244 times:

Whats

Quote:
a permanent magnet generating system

?

Cheers

EDIT: Never mind, google is my friend.

[Edited 2008-02-28 02:55:09]


John Hancock
User currently offlineScbriml From United Kingdom, joined Jul 2003, 12399 posts, RR: 46
Reply 3, posted (6 years 5 months 5 days 7 hours ago) and read 5049 times:
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I'd be surprised if this comes as news to Boeing. They said they were working very closely with the FAA to define the certification requirements, so it would be a bit of a shock if this is the first time the FAA has raised this issue with Boeing.

Quoting Smokeyrosco (Reply 2):
Whats

Quote:
a permanent magnet generating system

I suspect it's a system that generates a permanent magnet.  duck 



Time flies like an arrow, but fruit flies like a banana!
User currently offlinePilotboi From United States of America, joined Sep 2007, 2366 posts, RR: 9
Reply 4, posted (6 years 5 months 5 days 5 hours ago) and read 4894 times:

From the article:

Quote:
This change requires the aircraft's two engines to drive four auxiliary power units (APUs) generating 1.45mW of electricity

For being an aviation related news site, I can't believe they got this wrong. These are not called APUs, these are called Integrated Drive Generators (IDGs).


User currently offlineParapente From United Kingdom, joined Mar 2006, 1548 posts, RR: 10
Reply 5, posted (6 years 5 months 5 days 5 hours ago) and read 4889 times:

"This change....." so does it have 4 IDG's already or not. If its "a change" it suggests not. If it does then is it news at all? Confused!

User currently offlineStarlionblue From Greenland, joined Feb 2004, 17002 posts, RR: 67
Reply 6, posted (6 years 5 months 5 days 4 hours ago) and read 4884 times:

Is this really a big deal? Doesn't the FAA impose "special conditions" on pretty much any new major airliner since any new airliner will probably incorporate some sort of technological advance?


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinePilotboi From United States of America, joined Sep 2007, 2366 posts, RR: 9
Reply 7, posted (6 years 5 months 5 days 4 hours ago) and read 4868 times:



Quoting Pilotboi (Reply 4):
For being an aviation related news site, I can't believe they got this wrong. These are not called APUs, these are called Integrated Drive Generators (IDGs).



Quoting Parapente (Reply 5):
"This change....." so does it have 4 IDG's already or not. If its "a change" it suggests not. If it does then is it news at all? Confused!

The change the article is talking about the new FAA requirements for the aircraft.

The whole APU thing was just an error, but I brought it to the writer's attention and he has fixed it promptly.

It does already have 4 IDGs, 2 per engine. Nothing is changing there.

Quoting Starlionblue (Reply 6):
Is this really a big deal? Doesn't the FAA impose "special conditions" on pretty much any new major airliner since any new airliner will probably incorporate some sort of technological advance?

Basically, yes. But then of course, how could the FAA predict what the aircraft industry is going to come up with next?


User currently offlineNoWorries From United States of America, joined Oct 2006, 539 posts, RR: 1
Reply 8, posted (6 years 5 months 5 days 4 hours ago) and read 4868 times:

Looks like the article changed to say four IDGs instead of four APUs. Even this may not be strictly correct -- I don't know if they're still called IDGs because the 787 generators aren't regulated to a constant 400Hz, the frequency is allowed to float. I don't think it's a surprise to Boeing -- what's a little bit different here is that Boeing needs to prove it can restart everything if all electrical generators (including those driven by an APU) go offline. Even generators typically need an external electricity supply (to excite their field windings) -- so they need to prove that battery power and/or electricity from a permanent magnet generator is sufficient to get the system restarted.

User currently offlineParapente From United Kingdom, joined Mar 2006, 1548 posts, RR: 10
Reply 9, posted (6 years 5 months 5 days 3 hours ago) and read 4830 times:

Thank you No Worries. So fundamentally the basic engineering does not need to change but that the FAA require proof that it does do what they say it will do. In this case I imagine that they (Boeing) have already satisfied themselves that the electrical power system can stay "online" in the event of a total loss of mechanical power for the required FAA time. Is that right?

User currently offlineTod From Denmark, joined Aug 2004, 1724 posts, RR: 3
Reply 10, posted (6 years 5 months 5 days 3 hours ago) and read 4820 times:



Quoting Starlionblue (Reply 6):
Doesn't the FAA impose "special conditions" on pretty much any new major airliner

The 747, 757, 767 and 777 Type Certificate Data Sheets all list Special Conditions.

Tod


User currently offlineNoWorries From United States of America, joined Oct 2006, 539 posts, RR: 1
Reply 11, posted (6 years 5 months 5 days 3 hours ago) and read 4816 times:



Quoting Parapente (Reply 9):
Is that right?

I think so. Sort of a chicken and egg problem -- the mostly electric 787 systems need some electricity to get started -- it has to come from somewhere. I'm assuming the same problem (to a lesser degree) exists with more conventional designs -- on non-787s do engines/APUs still need some electric power to be restarted in flight? I'm assuming the issue on the 787 is that it needs more electric power than a typical plane to get everything restarted.


User currently offlineZeke From Hong Kong, joined Dec 2006, 8879 posts, RR: 75
Reply 12, posted (6 years 5 months 5 days 3 hours ago) and read 4803 times:



Quoting Starlionblue (Reply 6):
Is this really a big deal? Doesn't the FAA impose "special conditions" on pretty much any new major airliner since any new airliner will probably incorporate some sort of technological advance?

That is correct, FAA/EASA rules in many was lag behind new designs.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlinePilotboi From United States of America, joined Sep 2007, 2366 posts, RR: 9
Reply 13, posted (6 years 5 months 5 days 3 hours ago) and read 4791 times:



Quoting NoWorries (Reply 8):
I don't think it's a surprise to Boeing -- what's a little bit different here is that Boeing needs to prove it can restart everything if all electrical generators (including those driven by an APU) go offline.

I don't think that's the specific issue here. The issue they are talking about is making sure that the aircraft is capable of landing in the event of both engine loss. To do this, they need to ensure that the flight controls can be used after both engines are gone.

Quoting NoWorries (Reply 11):
I'm assuming the same problem (to a lesser degree) exists with more conventional designs -- on non-787s do engines/APUs still need some electric power to be restarted in flight? I'm assuming the issue on the 787 is that it needs more electric power than a typical plane to get everything restarted.

That sounds possible, as the starters (which are the IDGs) are electric only and no bleed air is used. But I would think the battery and RAT should provide adequate power to use the starters.

Quoting NoWorries (Reply 8):
I don't know if they're still called IDGs because the 787 generators aren't regulated to a constant 400Hz, the frequency is allowed to float.

True. For some reason they've still been labeling it as an IDG. But some articles do point out that it is not a typical IDG. Maybe they'll come up with a new name for it. But probably not...leading to more confusion.

Quoting Parapente (Reply 9):
In this case I imagine that they (Boeing) have already satisfied themselves that the electrical power system can stay "online" in the event of a total loss of mechanical power for the required FAA time. Is that right?

I would imagine so. I highly doubt Boeing would overlook this problem. I think it's all been done on paper, and numerous independent tests. But it all comes down to a true test when they get it in the air.


User currently offlineNoWorries From United States of America, joined Oct 2006, 539 posts, RR: 1
Reply 14, posted (6 years 5 months 5 days 1 hour ago) and read 4743 times:

Quoting Pilotboi (Reply 13):
I don't think that's the specific issue here. The issue they are talking about is making sure that the aircraft is capable of landing in the event of both engine loss. To do this, they need to ensure that the flight controls can be used after both engines are gone.

Ah, OK .. I think I get it now ... If a more conventional design loses all fuel-burning power sources (engines + APUs), it needs enough electrical power for flight computers (batteries) and enough hydraulic power for flight surfaces (pump on the RAT) -- what's different is that if the 787 loses all fuel-burning power, it needs more electricity (flight computers + control surface actuators) and hence bigger batteries and/or on the RAT a permanent magnetic generator (which doesn't need an external electricity source to operate).

This makes me wonder why a similar requirement doesn't exist for the A380 -- it's hydraulic pumps are electrically operated -- seems like that implies a similar need for greater emergency electrical power, or an assumption that all engines and APU's are extremely unlikely to fail simultaneously.

[Edited 2008-02-28 09:40:02]

User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 15, posted (6 years 5 months 5 days 1 hour ago) and read 4721 times:



Quoting Pilotboi (Reply 4):
For being an aviation related news site, I can't believe they got this wrong. These are not called APUs, these are called Integrated Drive Generators (IDGs).



Quoting Pilotboi (Reply 7):
It does already have 4 IDGs, 2 per engine.



Quoting Pilotboi (Reply 13):
the starters (which are the IDGs)

They're not IDG's. They don't have integrated drives (the "ID" part). They've VFSG's...Variable Frequency Starter Generators.

Quoting Starlionblue (Reply 6):
Is this really a big deal?

No.

Quoting Starlionblue (Reply 6):
Doesn't the FAA impose "special conditions" on pretty much any new major airliner since any new airliner will probably incorporate some sort of technological advance?

Yes. A "special condition" is just the FAA recognizing that the existing FAR's don't address some new technology. If you didn't have a special condition on a new aircraft I'd be very suspicious that the OEM wasn't using all the new tools that are available.

Quoting NoWorries (Reply 14):
what's different is that if the 787 loses all fuel-burning power, it needs more electricity (flight computers + control surface actuators)

The 787 still needs hydraulic power too...only the spoiler actuators are electric.

Quoting NoWorries (Reply 14):
This makes me wonder why a similar requirement doesn't exist for the A380 -- it's hydraulic pumps are electrically operated -- seems like that implies a similar need for greater emergency electrical power, or an assumption that all engines and APU's are extremely unlikely to fail simultaneously.

Quadruple engine failure isn't something that quad's are typically designed for.

Tom.


User currently offlineZeke From Hong Kong, joined Dec 2006, 8879 posts, RR: 75
Reply 16, posted (6 years 5 months 5 days 1 hour ago) and read 4719 times:



Quoting NoWorries (Reply 14):
This makes me wonder why a similar requirement doesn't exist for the A380 -- it's hydraulic pumps are electrically operated -- seems like that implies a similar need for greater emergency electrical power, or an assumption that all engines and APU's are extremely unlikely to fail simultaneously.

The A380 has dual actuators for control surfaces, hydraulic and electric, the hydraulic system pressure and electricity is engine generated (4 engine redundancy).

Electrical power is backed up with 4 engine driven generators, the APU, the RAT, and batteries. Hydraulic power is generated by each of the 4 engines, and the control surfaces are based up with Electrical Backup Hydraulic Actuators (EBHAs). They are a combination of a conventional servo-control and an Electro-Hydrostatic Actuators (EHA). In normal mode, they operate as conventional servocontrols. If there is a hydraulic failure, they operate as EHAs.

The A380 is the first large jet to be made for some time that has full redundancy in the event of total hydraulic system failure.

The electric hydraulic pumps are only on for ground operations like opening cargo doors.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 17, posted (6 years 5 months 5 days 1 hour ago) and read 4714 times:
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DATABASE EDITOR



Quoting NoWorries (Reply 8):
Even generators typically need an external electricity supply (to excite their field windings) -- so they need to prove that battery power and/or electricity from a permanent magnet generator is sufficient to get the system restarted.

Almost sounds like the FAA wants giant magnetos installed.  biggrin 

2H4



Intentionally Left Blank
User currently offlineLuv2cattlecall From United States of America, joined Sep 2007, 1650 posts, RR: 2
Reply 18, posted (6 years 5 months 5 days ago) and read 4670 times:
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Quoting NoWorries (Reply 8):
Even generators typically need an external electricity supply (to excite their field windings) --

There's a strong chance I have no clue what I'm talking about...but I thought it was alternators that needed an external electricity supply to excite the windings, while generators start cranking out the juice whenever they're rotating?



When you have to breaststroke to your connecting flight...it's a crash!
User currently offlineKELPkid From United States of America, joined Nov 2005, 6346 posts, RR: 3
Reply 19, posted (6 years 5 months 5 days ago) and read 4664 times:



Quoting Luv2cattlecall (Reply 18):
There's a strong chance I have no clue what I'm talking about...but I thought it was alternators that needed an external electricity supply to excite the windings, while generators start cranking out the juice whenever they're rotating?

Yup, however generators are much heavier than alternators, on account of the fact that they have to have very large permanent magnets inside the casing...



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlinePilotboi From United States of America, joined Sep 2007, 2366 posts, RR: 9
Reply 20, posted (6 years 5 months 5 days ago) and read 4657 times:



Quoting NoWorries (Reply 14):
Ah, OK .. I think I get it now ... If a more conventional design loses all fuel-burning power sources (engines + APUs), it needs enough electrical power for flight computers (batteries) and enough hydraulic power for flight surfaces (pump on the RAT) -- what's different is that if the 787 loses all fuel-burning power, it needs more electricity (flight computers + control surface actuators) and hence bigger batteries and/or on the RAT a permanent magnetic generator (which doesn't need an external electricity source to operate).

 checkmark  You've got it, except as Tdscanuck said:

Quoting Tdscanuck (Reply 15):
The 787 still needs hydraulic power too...only the spoiler actuators are electric.

(To backup what you said...) A lot of people forget that the 787 still has hydraulics. What has been eliminated is bleed air, not hydraulics. The hydraulic system is still there, but there's a slight change. In the 787, there is no air-driven hydraulic pumps, they are all electric. So this becomes a slight problem when you lose all electricity.

Quoting Tdscanuck (Reply 15):
They're not IDG's. They don't have integrated drives (the "ID" part). They've VFSG's...Variable Frequency Starter Generators.

Ah, that's a better name. All the documentation I've seen so far (including Boeing) has labeled them as IDGs.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6346 posts, RR: 3
Reply 21, posted (6 years 5 months 4 days 23 hours ago) and read 4650 times:



Quoting 2H4 (Reply 17):
Almost sounds like the FAA wants giant magnetos installed.

2H4

Imagine this in the 787 panel:

Big version: Width: 85 Height: 113 File size: 2kb


 Wink



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineNoWorries From United States of America, joined Oct 2006, 539 posts, RR: 1
Reply 22, posted (6 years 5 months 4 days 23 hours ago) and read 4639 times:



Quoting Luv2cattlecall (Reply 18):
There's a strong chance I have no clue what I'm talking about...but I thought it was alternators that needed an external electricity supply to excite the windings, while generators start cranking out the juice whenever they're rotating?



Quoting KELPkid (Reply 19):
Yup, however generators are much heavier than alternators, on account of the fact that they have to have very large permanent magnets inside the casing...

The terms alternator and generator have fairly loose definitions. Some assume than generator implies a DC generator, and alternator is a shortcut name for alternating current generator. Either can use permanent magnets or an electromagnets to supply the reactive field. Large generator/alternators almost always use an electromagnetic field. In an automobile, generator often implied the old heavy permanent magnet DC generator, and alternator is typically meant to imply a three-phase AC generator with an externally supplied field current -- hence you can't push start a car with an alternator without a least a trickle of electric current from the battery (at least this used to be the case -- now days with integrated starters/alternators and all sorts of hi-tech doodads my info may be dated). Also, with advancements in alloys, very powerful permanent magnets are now possible -- for example some hybrid cars have permanent magnet motor/generators.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6346 posts, RR: 3
Reply 23, posted (6 years 5 months 4 days 23 hours ago) and read 4615 times:



Quoting NoWorries (Reply 22):
hence you can't push start a car with an alternator without a least a trickle of electric current from the battery (at least this used to be the case -- now days with integrated starters/alternators and all sorts of hi-tech doodads my info may be dated).

I don't know that you could bump start a vehicle with a generator with a completely dead battery, either. The spark has to come from somewhere  Wink My old '64 Ford F-100 did have an electric ignition...



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineDl757md From United States of America, joined May 2004, 1562 posts, RR: 16
Reply 24, posted (6 years 5 months 4 days 21 hours ago) and read 4566 times:



Quoting Tdscanuck (Reply 15):
Quadruple engine failure isn't something that quad's are typically designed for.

They run out of fuel just as easily as twins and they have flamed out for other reasons like volcanic ash. Is there a design requirement that is specific only to twins that addresses dual engine failure?

DL757Md



757 Most beautiful airliner in the sky!
25 Zeke : No.
26 Tdscanuck : I got VFSG's off a Dec-2007 787 maintenance orientation...not sure if that's what will stick when it finally delivers but it seems to be current for
27 Post contains images Starlionblue : Or perhaps giant flywheels?
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