FAA - special conditions on Boeing 787

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posted on Feb, 28 2008 @ 02:13 PM
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www.flightglobal.com...


Boeing's "more-electric" power architecture for the 787 will face special conditions to achieve airworthiness certification by the US Federal Aviation Administration.

The extra certification requirements released by the FAA require Boeing to prove the 787 "is capable of recovering adequate primary electrical power generation for safe flight and landing" in the event of an in-flight power failure.



basically - the 787 removes the pneumatic systems used to power hydraulics - and replaces them with electric power hydraulics ; whilst this might seem an `omg` to remove the pneumatics - you must ask your self 1 thing - in the event of total failure (thats everything including all back-ups) - with NO mechanical back up anyway , all these FBW aircraft will just fall out of the sky , and if the engine and apu fail , then the ram air turbine is deployed -and boeing has to show that (and batteries) can power it.




posted on Feb, 29 2008 @ 05:25 AM
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Sorry Harlequin Im not clear on what you are saying. Do you see a problem with the 787 not having pneumatics or not having any mechanical backup?

Frankly I dont see there being any real issue as a loss of all pneumatics would directly imply a loss of all bleed air, and the only likely way for that to happen is to have a massive leak in the system (due to say severe damage) or total engine power loss. Either way you would be screwed if you were relying on pneumatics for critical systems. Frankly I see the 787 relying on a pyramid type system of electrically powered hydraulics as much safer. If ALL the primary engine driven generators fail then the APU will kick in. If this also fails, which only likely will happen due to fuel starvation or ingestion of foreign matter (eg: volcanic dust clouds), then no matter what the primary hydraulic system is driven by you are in trouble anyway. And if the RAT doesn't deploy or wont work then you would go to your last line of defence, the aircrafts main battery(s). Now if neither of those has worked then it would suggest you are either one very jinxed individual, or you are allready standing at the pearly gates waiting to get in!

As for the adequacy of the main batteries and generating capacity of the RAT, it is highly unlikely that Boeing would fit a sub par system as they are well aware of the consequences of failing to do so on a ground breaking aircaft, let alone the fact that they and Airbus know that very occasionally these systems have been used in the real world. Also it makes no sense to go to the trouble of actually fitting a RAT and failing to engineer one that meets needed capacity. There is little weight or financial saving to be made in doing that.

LEE.



posted on Feb, 29 2008 @ 05:30 AM
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^^ thats what i said - at first glance the article is worrisome , but after more reading you have to realise the situation where everything fails , you are in deep *muck* anyway.



posted on Feb, 29 2008 @ 05:38 AM
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Sorry Harlequin I misunderstood the point you were making. Yeah you would be in deep S%$T if nothing worked anyway.

LEE.



posted on Feb, 29 2008 @ 05:41 AM
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what they need to show is that the batteries and ram air turbine can power teh aircraft - but as we both said , if it gets to that point then its a flying brick



posted on Jan, 17 2013 @ 09:27 AM
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The high energy density battery system the engineers decided to use is Li ion and about the size of 2 car batteries. On paper this looked to be a superior technology offering the rapid charge rates and 5C discharge cycles airplanes in turnaround service would need.

Very worst case scenario the 787 would fly safer with NIMH technology the size of about 6 car batteries. Much less efficient on paper but you wouldn't be at risk of sudden catastrophic power failure.

After hearing the vents blow on my sealed acid UPS batteries recently I've decided to just buy a shottky diode and go NIMH. You feel really stupid sitting around breathing acid fumes and poisoning the land fills with lead every three years.



posted on Jan, 17 2013 @ 11:10 AM
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Pilots no longer fly aircraft.

They merely input their vote on what the aircraft should do. There no longer is any mechanical link between the pilots controls...and the planes control surfaces.

Whoever thought of Fly By Wire with no mechanical backup should be arrested and placed in prison. Many Fly By Wire aircraft have experienced electrical fires in the cockpits that filled the cockpits with smoke....some have even dropped from the sky and crashed.

Pilots no longer fly aircraft. They only input their votes. The 787 was doomed as soon as it was designed on paper.



posted on Jan, 17 2013 @ 11:15 AM
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reply to post by Pervius
 


Wow. You are so wrong it's not even funny. Pilots don't "vote" on what to do, they still fly the aircraft. And fly by wire aircraft are no more unsafe as a hydraulic aircraft is. I have never heard reports of "many fly by wire aircraft" filling the cockpit with smoke or "falling out of the sky" because of a FBW problem. And I follow these things a lot more than the average person.



posted on Jan, 17 2013 @ 11:16 AM
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Originally posted by Harlequin
in the event of total failure (thats everything including all back-ups) - with NO mechanical back up anyway , all these FBW aircraft will just fall out of the sky , and if the engine and apu fail , then the ram air turbine is deployed -and boeing has to show that (and batteries) can power it.


I'm sorry, but your post is ridiculous on several levels.

Firstly, all FBW aircraft currently in operation, or on the drawing boards, have mechanical backups to the flight controls - you can physically remove the flight computers from the aircraft and you would still have pitch, yaw and roll command authority on the aircraft.

Secondly, in the event of a dual engine failure, and the inability to start the APU, a Boeing 787 and an Airbus A330 (a plane that is now 20 years old) are in the same boat - minimal systems available based off the power available. You don't lose anything more in a Boeing 787 in that case than you do in the Airbus.

Thirdly, from the article Boeing must show the 787 is capable of safe flight with the engine and APUs inoperative. Alternate sources of power may include the battery, ram air turbine or a permanent magnet generating system. - isn't a special consideration above and beyond that which exists in the standard consideration of both the FAA and the EASA for any LCA that undergoes certification. The A380 was required to show the same thing during its certification.

FUD.





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