How Auxiliary Power Units Work | Part 1 : Starting

Aircraft type.
* Boeing 777-300ER

APU engine.
* Honeywell 331-500

Aircraft systems explained
* Auxiliary power unit
* Electrical load management system

Major components covered.
* Main and APU battery, power distribution panel, APU engine, air inlet duct, inlet door, apu dc pump, electric actuator, fuel cluster, ignition unit, igniter plug and APU controller.
* Reverse flow annular combustor, centrifugal compressor, axial flow turbine, swirler, fuel nozzle, accessory gearbox, electric starter, pawl clutch mechanism, impeller, diffuser, stator, rotor, exhaust duct and fuel manifolds.

Software's used for making the video.
* Blender 3.6 and Filmora 10

Background music used in the video.
* (Filmora stock library)

[SplashJohn]

I'm not in aviation, but I can recognize an excellent graphical and verbal presentation when I see one. Good work!

[thabg]

o man I remember the days on the flight line when I was in the Airforce having to listen to those screeching loud APU's 8-12 hrs a day, Yes I had (double) hearing protection. Its louder than the turbofan engine is (at idle). We used the APU to generate electrical & hydraulic pressure to load the gun system with ammo while at the same time removing the spent shell casings. There was a machine to connect to externally for electricity and hydraulics, it was taught to us in practice. But in real world use, it was never used, well at least not at the base I was at.

[ryanreedgibson]

My dad and brothers worked on the industrial piping for the Honeywell plant that rebuilt these in Arizona. The plant did nothing but rebuild these APUs all day long. Awesome video!

[kellyfernandx]

I'm studying this to help my fiancé answer a test at work... omg this is so complicated lol the engineering behind airplanes is just insane... amazing

[SimonButler]

I work on 777s every day and still found this presentation informative and well made! Great job!

[BlackFoxFalcon]

Masterpiece of engineering. Like pretty much everything in aviation.

[CHOXONCHOXOFF]

As usual, awesome animation and detailed. Keep going, we need such videos in our field for better understanding.

[grantnaval]

Now this. Is improvement!

Amazingly done as always.
From GE90 engine start and now goin' to the APU!

Amazing and great!
Thank you for this.

As an aircraft mechanic with this type training. YOU MADE EXPLAINING. Easy.

Always here to watch and see you go!

[DavK]

this is a damn good animation for those that are visual learners. thank you aircraft science for taking the time to make this

[주인공-mt]

crazy quality I’ve ever seen about APU

[gepset]

Great video. Interesting to see the APU follow the traditional British jet layout.

[jeylful]

Fabulous animation and explanation! Thank you!

[DropBear]

This was excellent. Your videos are getting better with every release. Thanks heaps!

[demal]

Heading been a ramp agent for a certain amount of time for a regional carrier, who used CRJ200's that had the APU exhaust at ground level, you had to walk quickly past all the heat if you were walking back there. (However in frigid temps it was a nice heat source outdoors lol)

[pdks]

Absolutely amazing work. So helpful video!

[rhiannacoady]

I will be starting to make these in Honeywell in a few weeks!! So excited!

[flapjack]

I've always wondered where the air intake for an APU was. Very cool!

[oOSpecialProskillsOo]

i am probably never going to need this knowledge, but it was very well broken down and presented, great job

[ccacrislan]

Absolutely brilliant, I really like and appreciate your job. Thank you. Always looking forward for more of your videos.

[motionsick]

This complexity is the reason there are no competitors to Boeing and Airbus. Such a colossal undertaking building a single one of these aircraft.