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simonriat
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Control Surfaces On The 787

Sat Dec 05, 2015 10:16 pm

Hi All

First off please dont flame me as I am not a pilot or anything connected with aviation.

An earlier topic with regard to loss of both engines at Vr, where all power would be lost, i.e hydraulic systems etc to control the aircraft, got me thinking.

Are the control surfaces on the 787 electrical or hydraulic operated? and with the loss of both engines would this result in loss of control of the aircraft?

Would the batteries kick in automatically? Could the APU provide any assistance?

On a final note, took my first flight on the aircraft and hats off to the designers, engineers, builders and flight crew of this wonderful aircraft. If only they could have added more loos!!!!!!
 
VC-10
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RE: Control Surfaces On The 787

Sun Dec 06, 2015 12:42 am

In general the Flt Ctrls are electrically controlled, hydraulically operated.

Ailerons - Hydraulic - Normal systems + RAT (Ram Air Turbine)
Elevators - Norm Hyds + RAT
Rudder - Norm Hyds + RAT
Spoilers (14) - # 4, 5, 10 & 11 are electrically operated, the remainder are hydraulic.
Slats/Flaps - Primary operation mode Hydraulic, secondary Electric

In an emergency situation the RAT will deploy automatically if the control system senses airspeed >80 Kts & no power on all the AC buses. It will deploy and be operational in less than 10 secs.Once up to speed will provide electrical & limited hydraulic power.

Until the RAT is up to speed the Flight Control Computers will be powered by their own batteries.

The APU can be used, but of course that takes time to start. The RAT is good enough to supply electrical power until the APU was started. Once started the APU can be used to power the main electric hyd pumps.

Finally the 787 may be good from the passengers POV but from a reliability POV it leaves a lot to be desired. Boeing will get it right in the end but for now it is not so good.
 
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Starlionblue
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RE: Control Surfaces On The 787

Sun Dec 06, 2015 2:43 am

Quoting simonriat (Thread starter):
Are the control surfaces on the 787 electrical or hydraulic operated? and with the loss of both engines would this result in loss of control of the aircraft?

Would the batteries kick in automatically? Could the APU provide any assistance?

If the aircraft lost of control with a dual flame-out it would not be certified. As VC-10 says, the RAT and the APU can provide hydraulic power.

This is similar to most airliners flying today.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
mmo
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RE: Control Surfaces On The 787

Sun Dec 06, 2015 7:24 am

Quoting VC-10 (Reply 1):
Finally the 787 may be good from the passengers POV but from a reliability POV it leaves a lot to be desired. Boeing will get it right in the end but for now it is not so good.

Care to quantify that? Your statement is very much at odds with what carriers are reporting. Granted the "terrible teens" are not matching the rest of the fleet, but the builds after that are doing extremely well. The carrier I work for is at 100% completion factor and the dispatch rate is above 99.6%.
If we weren't all crazy we'd all go insane!
 
simonriat
Topic Author
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RE: Control Surfaces On The 787

Sun Dec 06, 2015 8:56 am

Wow, in a way its still good to know that hydraulics are still used.

I would also hope that the pilots flying were vigilant enough not to let the speed drop that much.

Another question if I may. Are the wheel brakes electrically operated?

Im also going to assume there would be enough juice between the RAT and APU to allow radio communications?

I also thought that they were still having "quality" issues with aircraft coming out of the Charleston plant.

Sorry I am just fascinated by this aircraft, as a passenger I could not believe the difference, and I have flown on my types. My one regret is I will never get to fly on a DC10 or Concorde.

Thanks for the contributions so far........
 
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Starlionblue
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RE: Control Surfaces On The 787

Sun Dec 06, 2015 10:08 am

Quoting simonriat (Reply 4):
Im also going to assume there would be enough juice between the RAT and APU to allow radio communications?

Compared to control surfaces, radios are peanuts...
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
VC-10
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RE: Control Surfaces On The 787

Sun Dec 06, 2015 10:26 am

Quoting MMO (Reply 3):
Care to quantify that? Your statement is very much at odds with what carriers are reporting

Well we have been operating the 787 for a year now and we have had several AOG's at main base & down route. We have had issues with water getting into electrical junction boxes on the Ldg Gr (who would design an electrical loom and put a junction box on the underside of the MLG truck in all the spray off a wet runway). We even had one fault that rqd Boeing to replace an entire electrical rack.

I also have a friend who works for another 787 operator and he's not impressed either.
 
WIederling
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RE: Control Surfaces On The 787

Sun Dec 06, 2015 1:18 pm

Quoting simonriat (Reply 4):
Another question if I may. Are the wheel brakes electrically operated?

brakes are electric.
With no power beyond RAT available the main battery has to carry the full load.
( No meaningfull RAT power below landing speeds )
... and a very significant portion of its short term available capacity will be drained.
Murphy is an optimist
 
flyingcello
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RE: Control Surfaces On The 787

Sun Dec 06, 2015 2:04 pm

Are all hydraulics electrically pressurised? If so, are the engine generators self-excited? If not, windmilling can make no contribution?
 
WIederling
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RE: Control Surfaces On The 787

Sun Dec 06, 2015 2:23 pm

Quoting FLYINGCELLO (Reply 8):
If so, are the engine generators self-excited?

Trend is permanent magnet exitation independent of energy flow ( motor / generator )
i.e. syncronous multiphase devices. ( what's tagged as "BrushLess"DC )
Murphy is an optimist
 
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7BOEING7
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RE: Control Surfaces On The 787

Sun Dec 06, 2015 5:50 pm

If you lose normal electric power the battery takes over, the RAT pops out and the APU autostarts. When the RAT is up to speed it takes over for the battery. If the APU can't provide electrical power the RAT allows you to aviate (autopilot if desired), navigate (FMC and IRU's) and communicate (VHF and interphone) as well as providing hydraulic power for the primary flight controls. When it comes time to land it will be flaps up, no thrust reversers and once you're below 80 knots the battery takes over again. The RAT doesn't provide power to the brakes, their backup power source is the battery. If the RAT isn't working you need to find a place to land as soon as possible, the battery is not designed for long term use.
 
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Revelation
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RE: Control Surfaces On The 787

Mon Dec 07, 2015 1:24 pm

Quoting MMO (Reply 3):
Care to quantify that?

AvWeek has a recent article:

http://aviationweek.com/commercial-a...rs-apply-fixes-improve-reliability

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mmo
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RE: Control Surfaces On The 787

Mon Dec 07, 2015 2:29 pm

Quoting Revelation (Reply 11):

Quoting MMO (Reply 3):
Care to quantify that?

AvWeek has a recent article:

http://aviationweek.com/commercial-a...rs-apply-fixes-improve-reliability

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Quoting MMO (Reply 3):
Care to quantify that? Your statement is very much at odds with what carriers are reporting. Granted the "terrible teens" are not matching the rest of the fleet, but the builds after that are doing extremely well. The carrier I work for is at 100% completion factor and the dispatch rate is above 99.6%.

If you re-read my post you will see those art the frames I was talking about!!!! Notice the global fleet average is 98.5% and LAN is 98.8%. There are some operators who are 99.9% so, I would say the problem is internal on your end!!!!
If we weren't all crazy we'd all go insane!
 
WIederling
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RE: Control Surfaces On The 787

Mon Dec 07, 2015 2:43 pm

Quoting MMO (Reply 12):

cited from alternate: http://www.chinaaviationdaily.com/news/49/49262.html

As recently as a year ago, LAN's 787s performed well below the world average, with a dispatch reliability of only 96% compared to 98.5% for the global fleet. "We have now become much better," says Domenech. The fleet is currently at 98.8%.
The airline grounded each of its 10 787-8s for about 16 days to work on upgrades. Initial problems with spurious fault messages caused by immature display and control (DCA) software were solved with software updates, while upgrades were also needed in the electrical system to components such as panels, batteries and power generators. Hardware changes also affected the air conditioning and flight controls.

LAN got their first frame in Feb. 2015
10 month later 16 days of rework for frames that are not really out of warranty yet ?

Oy weyh, I'd deem that a manufacturer problem.
Hmm, are some Boeing customers "less equal pigs" than others ?

AI seems to have had their frames loaded with trashy stuff as well needing heavy rework.

addendum:
the article is a worthy read.
What I draw from this is that most of the 787 problems ( forex ground power sensitivities ) persist
but users have learned to work around most of them ( to varying degrees of success ).
LOT and their wet lease: maybe the higher rate is due not being serviced in Warsaw ?

[Edited 2015-12-07 06:59:26]
Murphy is an optimist
 
roseflyer
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RE: Control Surfaces On The 787

Mon Dec 07, 2015 4:37 pm

If you lose both engines at VR there still is battery backup for the flight deck controls and indication. The engines will still spin to provide hydraulic power while the rat deploys and spins up. The RAT and APU will provide sufficient electrical and hydraulic power for the plane. There are a combination of electrical pumps and mechanical pumps to power the hydraulics.

The problem with losing engines at VR will be having enough runway to stop. The likely catastrophic result of this failure requires significant redundancy in design. To be certified, the probability of any combination of failures has to be below one in a billion. With the way fault trees work, the probability is probably less than one in 10'billion.



Quoting WIederling (Reply 13):
LAN got their first frame in Feb. 2015
10 month later 16 days of rework for frames that are not really out of warranty yet ?

The earlier 787s have had an extremely high number of service bulletins issued to improve the plane. The airplane has more software than any other passenger airplane that flew before it and there have been many many upgrades. The 787 with its fast introduction into service and fast delivery rate has had more service bulletins released than any other airplane that I know of. Many airlines have chosen to get these bulletins incorporated faster than the typical C check cycle. The 787maintenance program is not check based and has longer frequency between required checks than other airplanes. It can have a 36 month C check frequency if an airline wanted depending on if they use C checks and what they want on A checks. The problem with that is that there is not as much ground time for service bulletins. With so many reliability improvements available some airlines have chosen to have ground time like C checks scheduled early. 16 days sounds like a normal C check, so it appears that LAN is trying to get bulletins done early on a special check. After these upgrades the airplane is performing very well.
If you have never designed an airplane part before, let the real designers do the work!
 
WIederling
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RE: Control Surfaces On The 787

Mon Dec 07, 2015 4:47 pm

Quoting roseflyer (Reply 14):
The earlier 787

A 2015 delivery is anything but .

Production is going through its 7th year.
They are at 10 frames a month.

And you tell me that they still bring out changes faster than MRO staff can integrate?
That is what I'd call FUBARed with elaborate care to details.
Murphy is an optimist
 
roseflyer
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RE: Control Surfaces On The 787

Mon Dec 07, 2015 6:54 pm

Quoting WIederling (Reply 15):

A 2015 delivery is anything but .

Production is going through its 7th year.
They are at 10 frames a month.

And you tell me that they still bring out changes faster than MRO staff can integrate?
That is what I'd call FUBARed with elaborate care to details.

LAN was the 4th airline to take delivery of 787s and took first delivery in 2012. The article is only referring to the 787-8s delivered. The newer 787-9s delivered in 2015 have not gone through that upgrade. I suspect the first ones took 16 days, but the later ones did not need as long as there would have been fewer service bulletins. The ones built in 2014 or 2015 don't need that many upgrades. If LAN is choosing to take them out of service as long as the ones hat have been flying for three years there must be something else causing that like them scheduling for their own convenience.
If you have never designed an airplane part before, let the real designers do the work!
 
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Polot
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RE: Control Surfaces On The 787

Mon Dec 07, 2015 8:33 pm

Quoting WIederling (Reply 13):
LAN got their first frame in Feb. 2015
10 month later 16 days of rework for frames that are not really out of warranty yet ?

Out of LAN's 10 788s (which needed the rework) 3 are from 2012, 2 from 2013, and 5 from 2014. LAN has only received 789s this year.
 
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seabosdca
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RE: Control Surfaces On The 787

Tue Dec 08, 2015 12:07 am

Quoting WIederling (Reply 13):
AI seems to have had their frames loaded with trashy stuff as well needing heavy rework.
AI was the fifth airline to take delivery of the 787, just five days after LAN took its first one. It presumably needed to make the same upgrades to the early frames as LAN (and ANA/JAL/Ethiopian). But where those other airlines either made the upgrades piecemeal or took frames out of service for a couple of weeks, AI kept its 2nd and 3rd deliveries out of service for 10 months each, and the 1st delivery has now been out of service for over a month.

[Edited 2015-12-07 16:07:47]
 
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Starlionblue
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RE: Control Surfaces On The 787

Tue Dec 08, 2015 12:13 am

Quoting Starlionblue (Reply 2):
As VC-10 says, the RAT and the APU can provide hydraulic power.

Oops. I must have been half-asleep when I wrote that. The APU does not provide hydraulic power, at least not on my plane. Don't know about the 787.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

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