Avionics bay of a United Airlines B787-9.

Yes they are. They are extremely heavy-duty power electronics (which is why they are liquid-cooled). Their weight is a trade-off against bleed air systems (and their reduced fuel efficiency) and mechanical constant speed drives for each generator.

the boeing spec winch is nearly good enough

I hope you provided that feedback to Boeing.

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cbs0308@reddit

When it works!

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ABoutDeSouffle@reddit

No one ever sweeps those floors, lol

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GardenPeep@reddit

Good: when I saw the photo my thoughts went to those undeclared lithium batteries in people's checked luggage..

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purduepilot@reddit

It’s more to reduce the wire weight on the airplane by adding the mid EE bay to keep the heavy electrical panels, conversion, and distribution equipment closer to the generators and big loads (motor-driven compressors and pumps, and wing anti-ice) while still keeping most of the avionics and flight controls equipment in the forward EE bay near the cockpit.

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BoringBob84@reddit

Reducing weight is certainly an advantage, but that is not the only reason. Remember the "shoe bomber?"

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purduepilot@reddit

The kind of separation you’re looking for is achieved by putting one of the ACEs by the aft cargo door, similar to 777. The use of two separate EE bays is not for redundancy; it’s for practical limitations of the size of the forward EE bay plus weight savings by minimizing the length of long wiring runs and keeping the motor controllers and power distribution elements nearer the generators and large electrical users. The 777X does not have a mid EE bay because it’s not required for systems separation.

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JPAV8R@reddit

Thanks for answering

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GodOfOpps@reddit (OP)

Yes they still do.(Electronics and Equipment bay.)

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jvttlus@reddit

I feel like Harrison ford is going to grab me from behind that corner

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W2ttsy@reddit

My first thought was Kurt Russell picking up a fried circuit and giving it to a sympathetic pilot

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tagish156@reddit

While Oliver Platt disables a bomb in the cargo bay.

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W2ttsy@reddit

Use your magic wand

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GeraintLlanfrechfa@reddit

And somebody is yelling about those motherfucking snakes on that motherfucking plane

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porsneiv@reddit

"Theres cant be two air marshals on board." *cue never ending fight scene and kicking of a gun

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patrick24601@reddit

Get off my plane !!

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thrilledquilt@reddit

Are there any VME crates still in use?

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GeraintLlanfrechfa@reddit

Only ARINC crates

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karmais4suckers@reddit

Oh that’s nice you can stand up in it

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Katana_DV20@reddit

Nice pic of something millions will never get to see IRL. To think that this is now "old " blow my mind. Its an amazing plane and I remember staying up to watch the first flight. All this stuff needs gobs of power and this leads nicely into a side note to your post..

Interestingly the 787 is the "most electric" airliner out there.

2 gens on each engine, 2 gens on the APU, 17 substations for localized demands called Remote Power Distribution Units (RPDUs). 3 external AC sources.

>The total available onboard electrical power is 1.45 megawatts, which is five times the power available on conventional pneumatic airliners.

This is in the region of enough power to supply electricity to a little town.

https://en.wikipedia.org/wiki/Boeing_787_Dreamliner

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GodOfOpps@reddit (OP)

Wow

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dpaanlka@reddit

As complicated as an airplane is, it doesn’t feel like it should need quite this much hardware? Always blows my mind. Seems like there can only be so many hardware sensors and actuators that all this stuff is talking to physically on the vehicle!

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Independent-Mix-5796@reddit

Well, there's some things to consider:

First, keep in mind that most of the hardware in the image is old and ruggedized. Despite their impressive sizes, they're built for durability/reliability first and pale in performance in comparison to even your smartphones. Also, don't forget that the 787 program was launched in the early 2000s -- try to think about how computers from the 1990s used to look like.

Secondly, the 787 has a lot of hardware redundancy. The CCS (Common Core System) itself, which is like the central brains/hearts of the plane, has two redundant cabinets that each contain eight (!) General Processing Modules (GPMs). Almost all other supporting modules also have at least double redundancy.

Finally, almost everything is tracked on a modern airliner. Hell, I'm fairly certain that even the lavatory soap dispensers are indirectly connected to the racks in the image in some way. In the aviation industry where the margins are surprisingly thin, airliners want every edge that they can have to reduce maintenance costs and avoid unforeseen mishaps -- and this includes digitizing everything so that ground crews can see everything via a single maintenance laptop.

All this may seem like a lot, but really all this hardware is how we've phased out flight engineers and why we no longer need entire racks of steam gauges in the cockpit anymore.

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KickFacemouth@reddit

I've pondered before how an airliner needs what's essentially a whole server room to operate, while a desktop computer can simulate the airliner and the whole world around it, but this comment really helps me understand why that is (or isn't). Thanks for that!

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muck2@reddit

Agreed. Also, compare the size of this avionics bay to a modern fighter jet, which surely needs way more processing power given the limits of its flight envelope?

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CivilianAsset@reddit

Believe it or not, not really no!!! This is actually a really cool question that people dont ask much!

While fighter jets do need advanced computers, it’s much different.
The Boeing 787 Dreamliner (and most modern commercial aircraft) quite literally fly themselves. If a pilot did all the pre-flight/flight plan/startup, put it on the runway, and then put you in his seat, you would really have no problem getting it in the air and getting to the destination. The autopilot systems on these aircraft are incredibly robust.

There is also TONS of redundancy with all of their systems as well, so that takes up extra space. And like the other commenter said, there’s 220–330 seats up above all with screens and entertainment systems, wifi, charging ports....supporting that from a flying tube takes a solid amount of equipment!

Some commercial airliners have a military variant, for example the Boeing 767 commercial airliner’s “twin” is the KC-46 Pegasus used for in-flight refueling. Their avionics bays will look very different from their commercial counterpart, as they don’t need to support 200+ civilians and their entertainment systems.

Fighter jets are kind of the opposite design philosophy. They absolutely have insanely advanced computers, but they’re way more integrated and optimized for size, weight, and performance. Instead of having a ton of separate boxes handling different systems like an airliner, a lot of that gets consolidated into a few powerful mission computers.

They also don’t have any of the “hotel load” stuff: no passenger systems, no cabin infrastructure, no entertainment, etc so that cuts out a huge amount of hardware right away. Everything on a fighter is focused on flying, radar, weapons systems, and electronic warfare.

So it’s not that fighters need less computing power, they actually need a ton, its just concentrated and miniaturized. Airliners are more like a flying ecosystem with hundreds of people and layers of redundancy, while a fighter jet is a high-performance weapon system with a pilot.

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Turbo_Normalized@reddit

The flight envelope has nothing to do with processing power. 99.9% of the "compute" on an airplane is not used for flight controls.

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Imaginary_Amoeba3461@reddit

Not a mechanic but modern commercial planes have a lot of line replaceable units, relatively ready to access so maintenance can just swap them out and get the plane flying again.

You could make it more compact but I suspect a lot of the serviceability would go away.

If you look at the amount of mechanic work time in hours required per one hour of flying a fighter jet around, it’s a lot.

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Ecthelion-O-Fountain@reddit

Mmm guess not

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ILikeFlyingMachines@reddit

Well for starters you have 3 COM Radios, 3 NAV Radios, ADF, DME and all that stuff, RADAR transceiver, each display probably has one computer, multiple redundante flight control computers, mutliple redundant air data computers, 2 Autopilots etc.

And then all the "unimportant" stuff like AC control, Satcom, IFE, Lights etc.

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railker@reddit

In addition to the other comments, there's also the note that what most people don't realize is how specialized those boxes are.

Like one of those boxes is probably for the flaps. It handles the commands to and monitors the position of the flaps. That is its job and all it does.

One of them is probably a PSEU which watches all the sensors on the airplane - landing gear up or down, doors open or closed. That is its job and all it does.

One is probably the fuel quantity computer, takes and calculates all the inputs from the fuel level sensors and outputs that for the display. That is its job and (relatively) all it does.

(Not a 787 mechanic so I don't know exactly what these things are called on that aircraft 😅)

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worktyworkwork@reddit

There are literally hundreds of displays on every longhaul plane. I’m not sure if they’re thin clients or not, but either way you probably need a half rack of servers to serve all their internet, streaming, music, etc needs.

Then you have all the actual servers for the flight systems them selves and their redundant backups. All the power systems, battery banks, transformers, panels, etc. all of it needs to be redundant as the consequences of failure are hundreds or thousands dead.

Then you have hydraulics, AC, etc the electromechanical systems.

There’s a ton going on in a modern airliner. There’s a reason they cost up to $400 million each.

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GodOfOpps@reddit (OP)

I agree! The plane has so many data collectors, and systems that all need this.

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DogsOutTheWindow@reddit

I spent many days/nights crawling through there, hated it at the time now I miss it. The 787 is an incredible airplane.

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GodOfOpps@reddit (OP)

How and why did you crawl through the E and E bay of a 787.

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DogsOutTheWindow@reddit

I worked on that program for many years and was involved with various projects all over the airplane, many of which were in the EE bays.

Looking back it was awesome to have a handprint on solving a lot of issues and making improvements to the airplane/build but there were many exhausting hours spent in there with no power in sweltering heat. I certainly felt for the manufacturing folks working in there day after day.

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CGR90@reddit

That EE Bay has been home for many years. Has been great to see how much it’s changed for the better to more effectively assemble it. Always told others “ be great at wiring this area and you’ll never have to fear for your job” lol.

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Impressive-Yak-7449@reddit

The -9 uses a lot more power than the -8. There was an issue in 2015 maybe where a sub-sub-contractor altered a dielectric material in the ATRU's causing them to fail. Frequently they took out the CSMC's as well. Fully serviced with coolant, they each weighed 120 (CSMC) to 140 (ATRU). Lugging them up through the cargo was a pain. They're designed to be hoisted up through the EE hatch, but getting the hoist was always a pain.

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DogsOutTheWindow@reddit

That sounds vaguely familiar, the dielectric part of it, but I could be misremembering. Which site were you at?

I do recall a tooling project that was building prototypes for getting heavy equipment into the bays, I left before it was finished so no clue if it ever got incorporated.

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Impressive-Yak-7449@reddit

The rainy place! Lol

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Impressive-Yak-7449@reddit

I miss it! Very spacious actually!

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Brilliant_Activity39@reddit

Anything to avoid those seat selection fees. 😁

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GardenPeep@reddit

I never thought about where the computers are on a plane.

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554TangoAlpha@reddit

That plane is seriously one big computer

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moofie74@reddit

That’s just one of the two EE bays.

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RetardedChimpanzee@reddit

Everything’s computer!

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Cornishlee@reddit

That reference is from a simpler time that I weirdly miss

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skyliners_a340@reddit

I don't think that's from simpler times.

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aviation-ModTeam@reddit

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deleted_by_reddit@reddit

[removed]

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This content was removed for breaking the r/aviation rules.

This subreddit is dedicated to aviation and the discussion of aviation, not politics and religion. For discussion of these subjects, please choose a more appropriate subreddit.

If you believe this was a mistake, please message the moderators through modmail. Thank you for participating in the r/aviation community.

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Jazzlike_Climate4189@reddit

1 year ago?

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GuyfromKK@reddit

A super computer

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jjcky@reddit

and a wing.

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GodOfOpps@reddit (OP)

Agreed. An engineering marvel.

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TrippinNL@reddit

No dust or dirty floor boards. Has to be a new bird

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ycarel@reddit

If someone here got to work on the A350 and the 787. How do they compare?

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ycarel@reddit

What is the thing on the right that is all covered with tape?

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genetichazzard@reddit

Remember the 787 is over 22 years old, so the hardware it was designed on is probably closer to 30 yerar old. Also all the computer components need to be modular, so if one part fails, you just replace that module. And each module has redundancy. What you don't want is over-integration in airline safety, so it will never be the case that once chip does everything like a modern smartphone or laptop does.

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gitbse@reddit

As a Challenger mechanic.... this looks like a dream.

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Marios03wrx@reddit

Who has a photo of them applying CIC in the E&E bay and other AVI bay on an "H" check on one of these planes.

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Rafxtt@reddit

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Rafxtt@reddit

Problem is when there's a Fatal Error

... I'll show myself out 👋

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Left_Ambassador_4090@reddit

On the Wikipedia article for the 2013 JAL battery fire, there's a a photo that looks eerily similar to this one that shows where the thermal runaway started.

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ILikeFlyingMachines@reddit

Yes because the battery is there, at least on Airbus

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VulgarButFluent@reddit

The battery in this photo is just behind the "no step" sign on the bottom. Chillin in its lil metal box

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Smooth-Reading-4180@reddit

peaceful

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BackgroundGrade@reddit

I am convinced the A220 has the least amount of avionic boxes for a modern plane. Our equipment bays are tiny, yet do the same things.

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ILikeFlyingMachines@reddit

It's also one of the most modern planes, so it would make sense.

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Matosinhoslover@reddit

I know less about the A220 than about the 787. Isn't the A220 more of a "traditionally build" aircraft in terms of hydraulics, materials used, pneumatic systems (de-ice, pressurisation,...) I suppose those factors also need some additional components in the EE bay of the 787.

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Apexnanoman@reddit

Airplane avionics always look like something from the 80s.

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ILikeFlyingMachines@reddit

Because they are

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Thakkmatic@reddit

That has to be significant weight to lug around. Do they try to move to higher density chips over time and consolidate the electronics into fewer mounted boxes or less weighty ones?

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ILikeFlyingMachines@reddit

Yes. But usually not as a retrofit, certifying is expensive.

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fanofairplanes@reddit

Everything's computer!

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CouchPotatoFamine@reddit

Stop with all the downloads…

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MidgetQB@reddit

You wouldn't download an airplane?

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flyingcanuck@reddit

Guys will seriously fly this and sit in cruise like, "I don't know man, the Airbus is just too computerized for me".

😅😅

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Denim-Luckies-n-Wry@reddit

Didja try re-racking the box ?

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TwoAmps@reddit

What is the Blancmange off to the right?

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SnooCookies6231@reddit

Super cool! My friend Cheryl from high school flies them, and is prob about to retire soon. Otoh I’m starting my flying full time in “retirement”. Quotes because I’m still going to keep working. But travel all around.

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TheOriginalCharnold@reddit

Random question, but is it common for flight crew access this area during flight? Very cool how organized it is

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bkirbs13@reddit

Nah, the access hatch is in the FWD Galley & can only be opened from below in the FWD Avionics bay.

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TheOriginalCharnold@reddit

That makes sense, you dont want someone unqualified touching anything😂

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jgmiller24094@reddit

Like small data center in the sky

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kkeennmm@reddit

are those sticks of dynamite on that bottom shelf?

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MattL-PA@reddit

Thats a lotta RS-232 cables dressed in $100k fat shrinkwrap!

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Independent-Mix-5796@reddit

um ackchyually the 787 mostly uses ARINC 664 and ARINC 429

so its more like ethernet cords and VGA cables dressed in fat shrinkwrap lol

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wiggum55555@reddit

Very cool. No wonder these aircraft cost what they do. SO many systems and backups and incredible design and engineering.. and THEN someone still has to manufacture and assemble it all.

Also... will it fit in my Homelab ?

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Ky1arStern@reddit

The best thing about the 787 avionics bay is that it is large enough to lay down in, and it is often kept air conditioned while there is power on the a/c during maintenance activity.

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paulvanbommel@reddit

If that is pressurized, they could cram a few more seats down there.

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Impressive-Yak-7449@reddit

It's hot and noisy as hell in there! Make sure to bring you ear plugs and a gallon of water

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jockel37@reddit

Ma'am what happens if I pull this cabke out?

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DynamiteWitLaserBeam@reddit

Also, what if... someone... already did?

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Independent-Mix-5796@reddit

The forward EE bay is and is actually accessed via the front of the passenger cabin. The next time you board a 787, if you look down as you enter you will literally see the access hatch for the forward EE bay.

Fun fact, I know some flight engineers that have had to be in the 787 EE bay while it was flying for certain tests. So honestly... if the airlines could, they honestly might try to put seats down there :P /s

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heyinternetman@reddit

That’s what I was thinking

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Carlito_2112@reddit

Don't give the airlines any ideas!

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onethousandmonkey@reddit

What is that clear pipe at the right for?

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Impressive-Yak-7449@reddit

Drain tube. They're all over commercial planes

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aegisone@reddit

What’s the height of the ceiling we’re looking at here? Comfortable to work in or nah?

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Impressive-Yak-7449@reddit

About 6 feet in the main section, but with wiring and plumbing a little lower so watch your head!

The tunnels are a bit shorter as you head forward to about 3 feet maybe.

The aft EE bay about the same height, but no tunnels.

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Fluffy-Proof-5175@reddit

I instantly thought this was a server room lol

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ActualSupervillain@reddit

Reminds me of an A350. Very cool. Can't wait to get my hands on one of these! Am mechanic

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Admirable-Food9942@reddit

Can it run doom?

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Geekenstein@reddit

Flip a few switches. There will be doom.

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GodOfOpps@reddit (OP)

Haha

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wanliu@reddit

Any sense of scale?

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WubWubMiller@reddit

That’s a lot of ARINC racks

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chizdfw@reddit

Nice cable management.

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oh-pointy-bird@reddit

This guy/gal cable manages.

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Ordinary-Researcher8@reddit

Thanks

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DrEarlGreyIII@reddit

don’t mention it

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Fairycharmd@reddit

Hey I can see my box from here…

Who took the cover off :/

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Stan_Halen_@reddit

So much room for activities.

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cosmicrae@reddit

Anything that advanced needs a PLC rack somewhere.

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MixDifferent2076@reddit

Mmmmm software

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GodOfOpps@reddit (OP)

Mmmmm

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post-explainer@reddit

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