Boeing B787-8 engine start with APU inoperative 

It's hard to fathom isn't it? All it takes is a flip of a switch compared to 5 groundcrew, 3 GPUs and a huffer cart.

It does!

Now you know 😉

Yeah, it's not like it happens every day.

The 787 is totally electric. It's made that way. It fully needs 3 GPUs to function with no APU. Engines start Electrically as well. (has electric starters for engines as well)

@@bd5av8r1I think you’re missing the entire point of his post - he knows it’s electric but is surprised just HOW MANY damn GPUs are required. Also they aren’t starters, they’re the generators that can revert function as starters.

If it turns the engines over, it s a starter as well. I see them daily here on position 3 here at work.

It’s called a VFSG (variable frequency starter generator). Essentially yes it a generator, but also a variable frequency starter to apply the power for starting/spooling. 2 per engine 👍😁

That's cool!

@@dennisvijverbergbrakesrele6098 thanks, they sent me out to Airbus Toulouse to help provide on-wing care so that was really interesting. What is it you do?

So it has electronic starters instead? That’s kinda wild, almost every aircraft I know of uses bleed air to spool up the engines.

​@@99domini99 With bypass ratio over 10:1, there isn't much excess HP air. Overall pressure ratio is 50:1. Starter motor is also a generator, providing anti ice and HVAC along with hotel loads.

@@99domini99I believe they’re starters then become generators once start is complete

Actually it requires 3 external sources for engine start :D

Just to give you some idea the small gas turbine P&W APU on a 787 makes 450kVA of electrical power. Same as a 5 tonne diesel cummins generator.

the 78 is a bleed less aircraft, so it's all electrical. using all 6 generators onboard (2 on the APU, and 4 on the engines) it can produce 1.45 MW of power

It's the starter on the one engine taking most of that power.

@@stargazer7644 787 APU and subsystems are actually able to start both engines simultaneously

Yeah, go outside.

It flabbergasted me to🧐

GPU’s are not synchronized, each will provide power to a separate circuit of the aircraft, these are isolated by the Bus Tie Relays. Then each will provide power to the common motor starter controller to provide power to the starter generator of the engine. Not sure about B787, but many two engines ETOPS aircraft don’t tie there busses to getter to equalize the loads during flight . At least it’s not done on the B777, it’s done on the B747 and MD11 for example. If you have an external power unit connected to the aircraft the aircraft uses what it gets. But it will try to match APU and or Engines generators to fase a frequency to make a non break transfer when GPU are selected off in the cockpit.

Crew didn’t want to board passengers until they would be confident the engine would start with the equipment we had connected.

Hello, you can flight without a working APU, depending aircraft, it can be inoperative for a certain amount of time, usually is a category C MEL item, and that is 10 days.

yeah, I was once on AA flight at ORD where we had an air start on one engine at the gate. pilot told us what was happening, said "dont worry, once its running, its running"

ETOPS is not possible with APU inop.

@@user-vk4vd7vr5t i was on a BA 787 PHL-LHR with the APU inop. The captain said there was a lot of paperwork necessary. It was incredibly loud during the sTArt and it seemed it took a long time

Flights over land of up to 4-5 hours are ok, I believe. Anything of that duration over water is not. Airliners with inop APUs fly all the time. It’s one of the things that can be deferred on an aircraft until it can get to a maintenance base. Perfectly safe.

I dunno man ask the guy who lived two doors down from our old house he seemed to do it a lot

Yes that was the point of it all.

Thank you! Cheers!

No. at least since it does not you dont have to worry about it snapping :D lol

You need two 90KVA for engine start. We used three as the GPU were bad and we were trying to figure out which one. Normally with a third connected you can run the airco system

@@dennisvijverbergbrakesrele6098 thank you very much for explaining.. I've experienced mixed performance with the newer generation TLD GPUs (like the ones in the video). Seems to me that the previous generation (mostly using Tier-2 Cummins or Deutz engines) are simpler and more reliable.

@@andrewsoemantri2691 We had a brand new one grenade a radiator fan about a year ago. It was only a month or two old at the time.

That’s not the way Boeing went, no architecture on the aircraft to do that, the starter generators can do the job (even just one). You just need GPU’s that are reliable. Don’t think Boeing will add something like that ever, it’s would just be dead weight and will just be rarely used.

It doesn't really solve the problem, you'll just be hooking up a bleed air cart instead of an additional GPU. You'd also end up with #1 and #2 engines being of different spec and a component that's not being used 99.5% of the time adding additional complexity and dead weight to the aircraft.

​@@lolvksthe whole aircraft is based on electricity as I know. No more bleed air and turbine drive AC compressors no bleed Air etc irs all electric. So the Generators work as starters as far as I now. So the whole pressure Air starter piping is not needed for saving weight and so on. It is a new generation of aircraft with the newest technology.

@@mr.slowhand3843 correct. Engine starts are done exclusively using electrical power through the VFSGs (variable frequency starter-generator). The only thing bleed air is used on the 787 is for engine anti icing.

The 787 does not start with air, it’s use electric starter/generators.

@ I did not say the 787 did, I said the cf6 required 200hp from the air starter, and no doubt these newer, larger engines require more (electric equivalent) power

The same engine is on the B747-8, but then with the air starter. The same hugger that start the CF6 (but a lot faster ) will start the GEnx.

The 787 is a different kind compared to other aircraft. It's main engine is started by two 250kVA AC starter-alternators, while other aircraft engines are mostly started by pneumatic power (bleed air) supplied by the APU or a ground cart. Starting the engine of the 787 takes a s*it load of electric power 🤐

@@barjan82 yea I was expecting this! the old air starters were clunky, but light weight.

They were actually "huffers" in those days.

there's a minimum requirement of PSI the cart has to put out to be able to start the engines. It's always preferable to use the APU

@@CrazyMrTimThe 787 doesn’t use bleed air to start it’s engines. The generators on the main engines (2 gen/motors each engine) double as starting motors, starting them electrically. No bleed air system is used on the 787 at all. The a/c packs and pressurizations system uses electrically operated compressors. The wing parts that are normally heated with bleed air are electrically heated. My understanding is that the engine anti ice system utilizes bleed air but that’s it. There isn’t a bleed air ductwork system throughout the plane like on other airliners. The APU, as well as the engines, drives 2 generators to power the electrical system of the 787. The bleed air system was eliminated due to the huge decrease in efficiency that occurs from taking bleed air off of an engine. Less compressed air through the combustion chamber and turbine = less thrust. There’s also the added benefit of eliminating a potential source of cabin air contamination by not utilizing engine bleed air for pressurization and ventilation.

@@jcolbyt82 Ah. My knowledge of the 787 is limited. I'm qualified on the CRJ, 737max, A320 family, and the 777, but we haven't had the 787 where i work

No more than 1/3rd, apparently, since they needed 3 of them for a successful start lol

@@CrazyMrTim do you still fly the triple? i had a few questions if you dont mind

Each APU starter generator it rate 225KVA

You'd think so, but that's the same sort of power that a single motor Tesla Model 3 can consume when you put your foot down and that motor isn't very big.

@@ZurOhki1 the model 3 motor does not have to fly all day and is not watercooled. it physcially cannot be as large as a EV motor if it has to fit in the engine.

​@@SupremeRuleroftheWorldTesla model 3 motors require a liquid cooling system. Think and research before you speak yeah?

@@haunter_1845 i know bloody well what i am talking about so take a step back and reconsider your comments before responding. and the starters in these planes DONT have liquid cooling but do have to handle more power in a even shorter burst than the motor in a tesla has to absorb.

@@franklinclinton6045 not that I know of, as the B787 is the only aircraft not using the bleed from the engines of air conditioning and heating.

Seems you need 3 by the looks of it

Boeing 787 All You must have a minimum of two external power sources to start the engine. You may use three external power sources to reduce the load shed in the cabin during right main engine start. Each external power source must have a minimum capacity of 90 kVA at 115 VAC. You cannot start the two engines at the same time if you use external power sources. If you have only two external power sources, they must be connected to the forward external power receptacles. If it is necessary to start both engines, it is recommended that you use the electrical power from the running engine to start the second engine.

@@surchrisDoes the running engine need to spool up to cross feed the other engine start?

@@edmondhung6097 Yes. With the one engine running, it now can start the other engine with the generators from the running engine. Electric Start, no bleed air used.....

@@surchrisI can assure you the 787 will not start with 2 external power sources only. It must have 3 :)

The real ☝️

Would need to be a pretty good sim to show the scuff marks around the fuel cap at 0:51

787 is electric start. No bleed air on the aircraft for anything

Not even close! A complete overhaul on its little brother the APS2700 is $717,000 dollars. The cost of the APS5000 is around $1.3 million dollars.

We had bad GPU’s they kept tripping during the start of the engines, after 3 GPU’s connected the engine finally wanted to start. Normally two 90KVA GPU connections should do the job, and with a third one you can run the airco packs.

I guess I don't understand why the engines don't start w/o a GPU. Is that something exclusive to the 787. Aviation always fascinates me even the areas I don't understand. I worked for an airline but always on the customer service side. Thank you for understanding

For starting the engine you need electricity, this is delivered by the Auxiliary Power Unit in the tail or by Ground Power Units. This aircraft had a APU that was inoperative, that why GPU ‘s are used to start the RH engine, once that one is working the power delivered by RH engine then starts the LH engine.

@@TheCarsche the 787 doesnt use a bleed air system where other aircraft would need an airstart cart i think its called the 787 can use electrical enrgy from gpus to spin up one of the 2 generators per engine and start the engine that way but you need atleast 2 to do it and if they are unreliable a 3rd might be neccessary

If you can't spin the compressor stage fast enough, there is not enough air through the engine to cool the burner cans, and you have a "hot start" which damages the engine. Once there is enough airflow, you can light off the fuel in the burner cans, which then accelerates the air from the compressor stage, providing airflow through the exhaust turbine, which in turns accelerates the compressor, providing more air, burning more fuel, generating more power in the exhaust turbine, and at a certain speed, the engine is self-sustaining and you can turn the starter off. It's all about the cooling of the burner cans.

Normal ground time are about 2 hours, some companies push it to 90 minutes if they arrived late. But then you want definitely a working APU.

Yes it is, you just need to take in account starter/generator duty cycles, you will have to wait 10 minutes after a start attempt if I am not mistaken.

@@dennisvijverbergbrakesrele6098 Thanks!!!

On the 787 the starter motor is actually the alternator which is used as an electrical motor to power the engine until it is self-sufficient. After starting the electrical motor becomes the AC generator again

Not on the B787, the have starter/generators on the engines.

787 doesnt use the bleed air system of conventional aircraft it replaces all the systems with electrical ones so starting engines /anti ice / ac is all done with electrical power

115VAC 400HZ and should be 90KVA rated

@@dennisvijverbergbrakesrele6098 thanks

Yea, can't you get a couple of guys to push the plane into the wind to start the engines? Works on my VW.

Jumper cable would be long and heavy.

Nope still to far away to get pulled into the engine at idle

Only you haven't because they use an air starter. The 787 is purely electric.

@@cjmillsnun LOL........how long have you been building jets

@@VulcancruiserDon’t have to build them to know how they function

@@10293 Spent 38 years in airline ops......from local to global operations.......

@@Vulcancruiser38 years in airline ops and you don’t know the ONE aircraft that’s famous for having no bleed air / fully electric start/anti-ice etc? …wow

Not required for a B787, it an all electric aircraft.

B787 is still ETOPS when APU is inop.

@@dennisvijverbergbrakesrele6098 right, i assume the ETOPS rating is reduced though?

Nothing made by a computer sim in this video, not really know how you would come to a conclusion like that.

Hello there, the GE engine has the same set up to start as the RR. Two starter/generators

Electric motors need power to operate. with the aircraft not running (APU not functioning), no power is being generated so its supplied by the external GPUs (Ground Power Units). As is noted in the video description, the aircraft's APU (auxiliary power unit) wasn't functional. Normally the APU provides electrical power when the 2 regular engines are not running. The APU is also used to provide the power needed to start the regular engines. Being smaller, the APU is much easier to start.

Not dangerous it you know what you are doing

It's fake from a simulator...

if that’s from a simulator I am impressed w the video quality!

We're all impressed by your ignorance.

You know that the bean counters that created the MD-80 are the same ones that replaced the engineers at Boeing, right?

Not on the B787, it doesn’t have the bleed air architecture to drive an air starter. It only has two starter/generators on the engine.

@@dennisvijverbergbrakesrele6098 ah ok I see. I don’t work with stuff that new so I’m glad you said that. The biggest thing I’ve air started is a CRJ 200

​@@dennisvijverbergbrakesrele6098no air cart capable?

Once #2 engine starts it overrides the power unit?

@@mgomez5606the one engine is way more than needed to start the other engine and power all the systems on the ground.

Well now I do 😂

Yes indeed, I doubt any aircraft operator would let someone wonder around their airplane filming, especially during engine start.

Of course it’s not. It might seem like it is but all his videos are genuine.

Wondered why nobody was there 😅

@@markcardwell but there are, you can see engineers in the background. He’s an engineer based in Miami. Flight simulator maybe realistic but it’s not this good yet. Look carefully, you’ll see engineers and ground staff.

Just wondering, how would you come to a conclusion that it is fake? Just through some other comments or is there something that is shown that is faked / unrealistic.

Dumbest comment of the year

@dennisvijverbergbrakesrele6098 I searched the internet for anything which came close to this story including the various aircraft investigation sites and found nothing

@@MarsVinette the video isn’t related to any incident or accident. APU was just inoperative and deferred iaw MEL.

How’s about no

What was the point of your post?