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Scooter01
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Boeing 789 Startup Procedure

Fri Feb 26, 2016 10:43 am

Watching the video of Norwegian's first 789 startup and delivery-flight

http://www.youtube.com/watch?v=Mm_gBRBMnxY

I noticed both engines being started at the same time (2:50)
and also a plume of blue smoke from the APU exaust (3:19)

-was this due to more power being needed to start both engines at the same time?


Just asking, since I've only been a passenger on a 788 twice and as far as I can remember the engines were started one at a time.


Scooter01
 
A320ajm
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RE: Boeing 789 Startup Procedure

Fri Feb 26, 2016 12:02 pm

Quoting Scooter01 (Thread starter):
and also a plume of blue smoke from the APU exaust (3:19)

Unless it was coincidence, did you notice the fire truck checking it out too?
 
mmo
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RE: Boeing 789 Startup Procedure

Fri Feb 26, 2016 2:04 pm

Quoting Scooter01 (Thread starter):
Just asking, since I've only been a passenger on a 788 twice and as far as I can remember the engines were started one at a time.

Generally speaking, most airlines will start one engine at a time just as a matter of standardization among the fleets. The airplane can handle starting both engines. When I was on the 744, I was involved in several delivery flights. The Boeing pilots would do the takeoff and once the business transaction was completed, I would jump in the seat. But, they started all 4 at the same time as the aircraft had the autostart option, which the 787 has as standard.

The apu puff of blue smoke could be a load of things. Increased demand for electrics would result in a change in bleed air, a contaminant in the hot section burning up or many other things.
 
roseflyer
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RE: Boeing 789 Startup Procedure

Fri Feb 26, 2016 2:35 pm

I believe that the 787 has autostart and will manage the electrical loads accordingly so that the pilots don't have to worry about starting both engines simultaneously. The 787 won't have hung starts due to pneumatic pressure dropping since obviously it has no pneumatic starters. The 787 does a good job of maintaining the correct power loads and dropping off power to non essential systems.
 
yeelep
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RE: Boeing 789 Startup Procedure

Fri Feb 26, 2016 2:56 pm

I don't believe the smoke is from the apu. Look at 3:16-3:18, you can see the blue smoke near the ground by the r/h main gear then traveling up in front of the r/h horizontal stab. The smoke is from the #2 engine just after light off, nothing unusual.
 
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7BOEING7
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RE: Boeing 789 Startup Procedure

Fri Feb 26, 2016 9:11 pm

Quoting mmo (Reply 2):
Generally speaking, most airlines will start one engine at a time just as a matter of standardization among the fleets. The airplane can handle starting both engines. When I was on the 744, I was involved in several delivery flights. The Boeing pilots would do the takeoff and once the business transaction was completed, I would jump in the seat. But, they started all 4 at the same time as the aircraft had the autostart option, which the 787 has as standard.

Autostart has nothing to do with the number of engines you can start at any given time, it's a safety feature that allows the engine to monitor itself during start.

All Boeing pneumatically started airplanes (727/737/757/767/777) can only start one at a time except for the 744 which can start two (most of the time) using either a manual start or an autostart. During certain wx conditions the APU may not be able to support two engines at once.

As for the Boeing pilots starting all four at once, they may have positioned all four ENGINE AUTOSTART switches to ON and pulled all of the START switches but at most they only positioned two FUEL CONTROL switches to RUN to commence the start sequence, followed by a third and fourth as the START switches popped back out.

As for delivery flights where the airplane is contractually bought in flight (a very small percentage), unless there were special circumstances (Boeing flight crew training pilots going with the customer), the customer pilot was in the seat (generally left) from prior to engine start and only one Boeing pilot was involved.
 
mmo
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RE: Boeing 789 Startup Procedure

Fri Feb 26, 2016 9:55 pm

Quoting 7BOEING7 (Reply 5):

Autostart has nothing to do with the number of engines you can start at any given time, it's a safety feature that allows the engine to monitor itself during start.

It certainly does. I know of no airline flying or that has flown the 744 that did not order autostart which started more than one engine at a time. Also, I am aware what Boeing aircraft have autostart. The only Boeing aircraft I have not flown is the 737.

Quoting 7BOEING7 (Reply 5):
As for delivery flights where the airplane is contractually bought in flight (a very small percentage), unless there were special circumstances (Boeing flight crew training pilots going with the customer), the customer pilot was in the seat (generally left) from prior to engine start and only one Boeing pilot was involve

I have done purchase flights for two different carriers at Boeing and a couple of different aircraft types. . In both instances the take off was done with Boeing pilots in both seats. Once the bank draft was handed over, a double seat swap was accomplished. Both carriers wanted it done that way for insurance purposes. Just like having to inform ATC of the new Reg Number.
 
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77west
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RE: Boeing 789 Startup Procedure

Fri Feb 26, 2016 10:51 pm

Quoting 7BOEING7 (Reply 5):
As for the Boeing pilots starting all four at once, they may have positioned all four ENGINE AUTOSTART switches to ON and pulled all of the START switches but at most they only positioned two FUEL CONTROL switches to RUN to commence the start sequence, followed by a third and fourth as the START switches popped back out.

I was under the impression that as soon as you pulled the start switch out, it began the spool up of the engine, thus using pneumatic pressure. The fuel control just allows the engine to light up and start spinning on its own.
 
BoeingGuy
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RE: Boeing 789 Startup Procedure

Sat Feb 27, 2016 12:37 am

Quoting mmo (Reply 6):
Quoting 7BOEING7 (Reply 5):

Autostart has nothing to do with the number of engines you can start at any given time, it's a safety feature that allows the engine to monitor itself during start.

It certainly does. I know of no airline flying or that has flown the 744 that did not order autostart which started more than one engine at a time. Also, I am aware what Boeing aircraft have autostart. The only Boeing aircraft I have not flown is the 737.

Autostart airplanes are 787, 777, 747-8, and it was optional on the 747-400.  

My understanding is also that it's prohibited/not recommended to start more than one engine at once if you don't have Autostart since you have to manually monitor the engine parameters as it spools up.

I'm not sure about the 787, but on the 777 you can only start both engines at once with PW and RR engines. You cannot start two engines at once with GE engines. I believe it has to do with the size of the engine and greater bleed air requirements to start.

[Edited 2016-02-26 16:39:27]
 
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7BOEING7
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RE: Boeing 789 Startup Procedure

Sat Feb 27, 2016 12:51 am

Quoting 77west (Reply 7):
I was under the impression that as soon as you pulled the start switch out, it began the spool up of the engine, thus using pneumatic pressure. The fuel control just allows the engine to light up and start spinning on its own.

If you're doing a manual start on the 747 that is true, however when AUTOSTART is selected ON, the start valve is only armed and doesn't open to provide bleed air to start the engine until the FUEL CONTROL switch is placed to RUN. On the 777 the engine will spool up when the START selector is positioned to START with AUTOSTART switch selected ON. Similarly on the 787 the engine will spool up when the START selector is positioned to START -- there is no manual start capability. All other Boeing's do not have autostart and operate as you described.
 
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7BOEING7
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RE: Boeing 789 Startup Procedure

Sat Feb 27, 2016 1:16 am

Quoting BoeingGuy (Reply 8):
I'm not sure about the 787, but on the 777 you can only start both engines at once with PW and RR engines.

  

My bad (memory), I forgot about the PW's and RR's. You can start the engines simultaneously on the 787 using the APU if both APU generators are available. If you don't have enough power it will automatically only start one.
 
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7BOEING7
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RE: Boeing 789 Startup Procedure

Sat Feb 27, 2016 1:30 am

Quoting mmo (Reply 6):
Autostart has nothing to do with the number of engines you can start at any given time, it's a safety feature that allows the engine to monitor itself during start.
It certainly does. I know of no airline flying or that has flown the 744 that did not order autostart which started more than one engine at a time. Also, I am aware what Boeing aircraft have autostart. The only Boeing aircraft I have not flown is the 737.

OK, I'll rephrase that comment. "Physically" autostart has nothing to do with the number of engines you can start, "operationally" I guess it does. As for starting 4 engines simultaneously in my experience that would be "physically" impossible.
 
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Scooter01
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RE: Boeing 789 Startup Procedure

Sat Feb 27, 2016 6:58 am

Quoting yeelep (Reply 4):
I don't believe the smoke is from the apu. Look at 3:16-3:18, you can see the blue smoke near the ground by the r/h main gear then traveling up in front of the r/h horizontal stab. The smoke is from the #2 engine just after light off, nothing unusual.

After re-examining the video, it looks like your'e right.

Scooter01
 
B777LRF
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RE: Boeing 789 Startup Procedure

Sat Feb 27, 2016 10:42 am

Regardless of whether you're resuscitating one or both at the same time, those electrically started 787 engines sure take a very long time indeed, before they breathing on their own.

Recently flew jumpseat on a 737NG and marvelled at how quickly the engines come on line. My reference point will always be the 757 with RB211s, which was hardly quick off the blocks either. Still positively sprightly compared to a 787, whether it be RR or GE hanging off those plastic wings.
 
Tristarsteve
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RE: Boeing 789 Startup Procedure

Sat Feb 27, 2016 11:46 am

Quoting BoeingGuy (Reply 8):
Autostart airplanes are 787, 777, 747-8, and it was optional on the 747-400

Many years ago a B744 was being delivered. It was the first B744 for the airline. It did not have autostart. The aircraft was flown from Seattle to Europe, where a new crew took over to fly it home. During their training, all the simulators had autostart, and that was how they were trained. They attempted to autostart two engines at once. Resulting in two engine changes as the fuel and ign was on, but the starter was not turning and the engine overtemped.
 
BoeingGuy
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RE: Boeing 789 Startup Procedure

Sat Feb 27, 2016 6:12 pm

Quoting B777LRF (Reply 13):
Recently flew jumpseat on a 737NG and marvelled at how quickly the engines come on line. My reference point will always be the 757 with RB211s, which was hardly quick off the blocks either. Still positively sprightly compared to a 787, whether it be RR or GE hanging off those plastic wings.

Does that have to do with the great bypass ratio on the 787? I know the engines with high bypass ratios take longer to start during an inflight windmill start. Is the same true for a ground start?
 
BravoOne
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RE: Boeing 789 Startup Procedure

Sat Feb 27, 2016 6:48 pm

Heck, you could start all four engines at once on the 707 if you had a really powerful ground start compressor. Just hold all for start switches down at once and move the start levers up at once   No big deal.
 
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77west
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RE: Boeing 789 Startup Procedure

Sat Feb 27, 2016 8:43 pm

I believe in some cases it is also to reduce the load on the pushback tug, as all engines running even at idle produce a few thousand pounds of load on the tug.

So Number 2 started during push and number 1 started while the ground crew are disconnecting tug etc.

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