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.
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 👍😁
@@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?
B787 is mostly an all electrical aircraft where ii doesn't use bleed air to power its system but requires 2 ac power gpu to spin its engine when APU is inop.
@@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.
Interesting, I never expected generators to be the start cart instead of the overgrown leaf blower ones. And those are big generators, never knew an airliner consumed that much electrical power.
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
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.
What is protocol with INOP APU? Can you fly revenue flights with pax or not? I once had an AA 738 flight out of DFW and they started one engine while we were still at the gate and obviously before we were pushed back. I wondered if the APU was INOP on that plane. Cheers, thanks for sharing!
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"
@@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.
did this on a CX+ lol in Chile - no aux apu - Rolls ae 3007 engines that didn't like starting without an external power source! disagreed with us heavily!
I know that each cable-plug set has a max. capability of 90KVA. So I assume you would need 3ea of healthy 90KVA GPUs to perform the engine-start and not tripping?
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.
I'm curious as to whether or not it would have been possible for the 787 to have an air starter on the #2 engine as a secondary means of starting for such cases where the APU is inoperative. This would allow the #2 engine to start using the normal means of an air cart and then generate enough electrical power to start the #1 engine.
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.
@ 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 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 🤐
@@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
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.
@@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.
So I'm guessing the 787 needs only gpu for starting up the engines because it has no traditional air bleeding system. Am I right? Didn't know you would need 2 gpu's if the APU is inop to do it though. Glad to see a Spanish airline in the channel btw :) (Also an Iberia A330 on the next gate)
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.
@@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.....
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.
Man, I would hate to work with heavies. I work with 320s all day and doing an air start, with a full flight, with an airstart, it's almot impossible to make a 40 minute turn. What's the minimum turn time for a heavy like this? 1 ground power connection and 1 air hose is all I really want to deal with xD
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.
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
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
@@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
Totalmente falso cuando los motores estan operando dos luces rojas una en el fuselaje superior y otra en el fuselaje inferior dan indicación de operaciones de motores y aqui no se ven esas luces aplicadas ni tampoco estaría el personal caminando dentro del area de succión y expulsión de los motores
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.
Yeah, I'm all set with never flying a Boeing aircraft again in my life. Airbus all the way, hell I'd rather fly a McDonnell Douglas MD-80 over anything Boeing is putting in the sky today.
@@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
@@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.
This whole thing is fake. It never happened. It is computer generated #Dennis Vijverberg, the person who posted. I'm tired of these individuals posting this nonsense.
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.
@dennisvijverbergbrakesrele6098 I searched the internet for anything which came close to this story including the various aircraft investigation sites and found nothing