KrisYYZ From Canada, joined Nov 2004, 1008 posts, RR: 0 Posted (2 months 1 week 3 days 14 hours ago) and read 2889 times:
I was under the impression that all Triple 7s start up both engines at the same time. I was recently told that this is not true on the B77W where each engine is started one at a time. I would assume that the more powerful GE 90-115B has a lot to do with this as they would require more power and air to start up verses the older GE90s, Trent 800s and PW 4000s. Does the B77L also require individual engine start up? Is there any difference in the bleed system on the older 777s and the newer generation 777s?
Transpac787 From United States, joined Jul 2007, 1058 posts, RR: 4 Reply 1, posted (2 months 1 week 3 days 12 hours ago) and read 2842 times:
I could have something to do with the size of the APU being able to start up both at once. It could also be due to an individual airline's procedure. At UA, standard 777 procedure is to start up both engines at the same time.
Like you mentioned though, the GE90-110B and GE90-115B might require a substantially greater amount of induction air than the Trents, PW's, or smaller GE90's, thus eclipsing the capability of the given APU.
On the 742, for example, the APU only provided enough air to start a single engine at a time, meaning a fairly long time to get all 4 spinning. The 744 though, has an APU that can start two at time.
"Can't we have one meeting that doesn't end with us digging up a corpse??" - Diamond Joe Quimby
Qantas744ER From San Marino, joined Jun 2005, 1054 posts, RR: 4 Reply 2, posted (2 months 1 week 3 days 2 hours ago) and read 2711 times:
Quoting Transpac787 (Reply 1): On the 742, for example, the APU only provided enough air to start a single engine at a time, meaning a fairly long time to get all 4 spinning. The 744 though, has an APU that can start two at time.
The APU on the 744 provides enough bleed to start all 4 at the time with an AUTOSTART( with autostart off this would never be done as it would require far to much simulataneous monitoring for all four by the crew during start up) . This of course is not done as it puts a larger strain on the APU. Some airline SOP's state one at the time, and others in pairs. just depends from the airline and engines.
UA who operate the PW4056 on their 744's will start one at the time, and all their 744's have AUTOSTART.
PhilSquares will give you a far better answer then me though!
Leo
The Boeing 747-400 will always be the Queen of the Skies!
Boeing767mech From United States, joined Dec 2000, 455 posts, RR: 1 Reply 3, posted (2 months 1 week 2 days 17 hours ago) and read 2610 times:
When I was still based in LA, we had a couple of mechanics that would start both engines at the same time on a 767. It would do it with a good APU and a nice on shore wind to cool down the temp. I know it's not SOP but it will do it with out overtemping the engines at 23 ASL in LAX
David
If it wasn't for maintainence, pilots wouldn't be able to get it up in the morning
PhilSquares From Ireland, joined Mar 2004, 3470 posts, RR: 52 Reply 4, posted (2 months 1 week 2 days 15 hours ago) and read 2592 times:
Quoting Qantas744ER (Reply 2): The APU on the 744 provides enough bleed to start all 4 at the time with an AUTOSTART( with autostart off this would never be done as it would require far to much simulataneous monitoring for all four by the crew during start up)
The 744 will do just fine starting all 4 engines simultaneously, with or with out Auto Start. However, for those airlines who did not order autostart, for example SQ, it would be an accident waiting to happen.
Most carriers adopted the classic's SOP when possible and as a result, I can't think of any operator that starts more than one engine at a time. Normal start sequence is accomplished one engine at a time, and either 4, 1,2,3 or 1,2,3,4.
FlyMIA From United States, joined Jun 2001, 3403 posts, RR: 3 Reply 5, posted (2 months 1 week 2 days 12 hours ago) and read 2537 times:
Quoting PhilSquares (Reply 4): I can't think of any operator that starts more than one engine at a time. Normal start sequence is accomplished one engine at a time, and either 4, 1,2,3 or 1,2,3,4.
When watching a cockpit video of a LH 744 crew they started 2 engines at a time on their 744. Captain said to the FO start engines 3 and 4, and after those two engines where up he said 2 and 1 and you could see both engines being run up.
Qantas744ER From San Marino, joined Jun 2005, 1054 posts, RR: 4 Reply 6, posted (2 months 1 week 2 days 10 hours ago) and read 2493 times:
Quoting PhilSquares (Reply 4): The 744 will do just fine starting all 4 engines simultaneously, with or with out Auto Start. However, for those airlines who did not order autostart, for example SQ, it would be an accident waiting to happen.
Most carriers adopted the classic's SOP when possible and as a result, I can't think of any operator that starts more than one engine at a time. Normal start sequence is accomplished one engine at a time, and either 4, 1,2,3 or 1,2,3,4.
Thanks once again for the quick answer!
It's great to have you here
Quoting FlyMIA (Reply 5): When watching a cockpit video of a LH 744 crew they started 2 engines at a time on their 744. Captain said to the FO start engines 3 and 4, and after those two engines where up he said 2 and 1 and you could see both engines being run up.
Yes and LH have auto start and a different SOP. Point is that without auto start the monitoring of the engines is very important in case of a hot start etc. for the crew to take the right steps to shut down and re-try without killing the engine. Because with out auto start you do not have the full engine protection during start.
Leo
The Boeing 747-400 will always be the Queen of the Skies!
TristarSteve From Sweden, joined Nov 2005, 2125 posts, RR: 11 Reply 7, posted (2 months 1 week 2 days 9 hours ago) and read 2480 times:
Quoting Qantas744ER (Reply 6): Because with out auto start you do not have the full engine protection during start.
It should be part of your check list to check that autostart is selected.
Thre was once a B744 crew that trained on a simulator with autostart. They then positioned to CDG to pick up a brand new B744 on delivery to their airline. They used autostart to start the engines two at a tiime. Unfortunately their airline had not specified autostart. We had to change two engines.
KrisYYZ From Canada, joined Nov 2004, 1008 posts, RR: 0 Reply 8, posted (2 months 1 week 2 days 9 hours ago) and read 2469 times:
Quoting Qantas744ER (Reply 2): UA who operate the PW4056 on their 744's will start one at the time, and all their 744's have AUTOSTART.
How about on the B777?
I was watching the UA B777 Justplanes video and the Capt started both engines at once. I've herd from charliecossie that most B777 operators start each engine one at a time, so how come some airline choose not to utilize the simultaneous engine start function on the B777?
CX flyboy From Hong Kong SAR, PRC, joined Dec 1999, 5356 posts, RR: 53 Reply 9, posted (2 months 1 week 2 days 4 hours ago) and read 2388 times:
You are correct. The smaller engines on the 777 require less air to start and SOP is to start both at the same time. This is for the Trent and the P&W.
The GE90 is substantially bigger and requires more air and thus we start one at a time. This goes for the 772ER, 77L or 77W all with GE90s. The APU is actually capable of starting 2 GE90s at the same time but we do not do it as SOP as there would be cases like high altitude airports where he APU would not be able to cope and you don't want a double hung start because of it. We just start the first engine earlier during pushback, so it does not delay the entire start-up process much unless we are at airports which do not allow us to start until the pushback is complete.
AA737-823 From United States, joined Mar 2000, 3302 posts, RR: 5 Reply 10, posted (2 months 1 week 1 day 19 hours ago) and read 2310 times:
Kris,
It's entirely up to the airline- the manufacturer does not write the SOP!!!
The above reply may be true for that man's carrier, but not all.
I have watched Pratt 4000's started simultaneously (a laborious, long-term affair... but then, so is starting ANY large Pratt) and started individually.
That said, I have never seen a Pratt powered 747 start multiple engines simultaneously. But I have seen it done on the Triple.
I'm under the impression that some GE-90-94 operators do dual-starts, actually, but don't have anything to back it up.
For unto us a Child is born- unto us a Son is given!
Viscount724 From Switzerland, joined Oct 2006, 6193 posts, RR: 1 Reply 11, posted (2 months 1 week 1 day 8 hours ago) and read 2188 times:
Quoting PhilSquares (Reply 4): I can't think of any operator that starts more than one engine at a time. Normal start sequence is accomplished one engine at a time, and either 4,1,2,3 or 1,2,3,4.
That prompts another question out of curiosity. I recall that it was common to start engines on 4-engine piston/turboprop types in the sequence 3,4,2,1. I think that was also common in the early jet era. Is that no longer the usual practice on 4-engine jets now?
TristarSteve From Sweden, joined Nov 2005, 2125 posts, RR: 11 Reply 12, posted (2 months 1 week 1 day 8 hours ago) and read 2183 times:
Quoting Viscount724 (Reply 11): I recall that it was common to start engines on 4-engine piston/turboprop types in the sequence 3,4,2,1. I think that was also common in the early jet era. Is that no longer the usual practice on 4-engine jets now?
On the B744 it is all to do with the hydraulic systems and the brakes they power.
JetMech From Australia, joined Mar 2006, 1882 posts, RR: 32 Reply 13, posted (2 months 1 week 1 day 7 hours ago) and read 2172 times:
Quoting PhilSquares (Reply 4): The 744 will do just fine starting all 4 engines simultaneously, with or with out Auto Start.
Wow, I never knew the 744 APU had enough grunt to start all four engines simultaneously! However, I have once seen something similar occur. I was doing the push and tow an a 747 (Aerolineas Argentinas), and for some reason, the flight engineer left all the packs on as the engine were started. The engine did eventually start, but as you can imagine, it took a long time to get up to speed.
Quoting Viscount724 (Reply 11): I think that was also common in the early jet era. Is that no longer the usual practice on 4-engine jets now?
On many 747 flights, if given the option, most crews usually start #4 engine first. The reason is that primary brakes on the 747 runs off # 4 system. #1, #2 and #3 are usually started in sequence afterwards. Co-incidently, #1 and #2 hydraulic systems are the first alternate and second alternate systems for brakes on the 744 ( and 747 classic? ).
Regards, JetMech
The universe revolves around engineers as we choose the co-ordinate system!
AA737-823 From United States, joined Mar 2000, 3302 posts, RR: 5 Reply 14, posted (2 months 1 week 21 hours ago) and read 2097 times:
Quoting PhilSquares (Reply 4): I can't think of any operator that starts more than one engine at a time.
JAL does it routinely. Dual starts 3-4, followed by 2-1.
Quoting TristarSteve (Reply 12): On the B744 it is all to do with the hydraulic systems and the brakes they power.
Not necessarily, from my own observation. Barring dual starts, JAL will do 4-3-2-1, while I have watched Cathay do 4-1-3-2. Recently flew on KLM, and they did 1-2-3-4... go figure. But then, they're Dutch.
Quoting JetMech (Reply 13): Wow, I never knew the 744 APU had enough grunt to start all four engines simultaneously!
I am not entirely convinced of this rumor, see as follows:
Quoting JetMech (Reply 13): flight engineer left all the packs on as the engine were started.
I know you can leave two packs on and start one engine, but I also know that in order for JAL do to dual starts, they were only allowed to run one pack. And they fly GE's.... with a Pratt, it's a miracle that the thing will spin at all, even with an APU coupled to a ground start cart!
Considering the remarkably greater amount of air required to start 4 engines than 2 (hint: it's double), you've run out of packs to shut down. With as little airflow as you're now dealing with, you've left the door wide open to a hot start or hung start.
Quoting JetMech (Reply 13): #1, #2 and #3 are usually started in sequence afterwards.
Again, depends on the airline. I have never seen a carrier do it the way you've described- which leads me only to believe that I've never watched the carrier you're watching.
For unto us a Child is born- unto us a Son is given!
TristarSteve From Sweden, joined Nov 2005, 2125 posts, RR: 11 Reply 15, posted (2 months 1 week 20 hours ago) and read 2084 times:
Reading this makes me think how easy it all is nowadays. I push back a B777 every day and I delay the start up until we are nearly at the stop posn. The crew then start them together and 30secs later I am walking away with the pin.
In an earlier life I used to start up Tristars in BAH. In the summer with a normal APU (i.e low pressure) we used to start Nbr2 first because it was closest to the APU. Drill was B and C hyd pumps off, Aft fuselage pneumatic isolation closed, then select start. Wait until the N3 stops increasing and fuel on. Watch the EGT and N3 like a hawk and at about 40pc N3 open the pneumatic isolation valve and select a pack on. The start took around 2 minutes, then to start 1 and 3.
You closed the air valve to reduce air losses in the ducts. You opened it again because when the starter cut out there was a good chance the APU would surge and shut down.
It was also dramatic starting them up in ARN at M15degC after a night stop. Same procedure but as the engine motored over you had to watch the oil pressure rise off scale high, and the oil quantity go to zero. Fuel on and not much happened except clouds of fuel out the back of the engine. Finally a slow rumble as the engine laboured into life and slowly crept up to idle. A little while later the oil quantity would slowly rise and the pressure start to drop. I have seen a L1011 completely fill the cul-de-sac with smoke, with the attendant fire engines trying to put out the non-existent fire.
The big change from the R211-22B to the Trent 800 is the surge margin in the engine. In the RB211 it was tiny, and fuel could only be introduced very slowly to stop the engine stalling. In the Trent it is huge and the beast goes straight to idle.
JetMech From Australia, joined Mar 2006, 1882 posts, RR: 32 Reply 16, posted (2 months 1 week 19 hours ago) and read 2081 times:
Quoting AA737-823 (Reply 14): Quoting TristarSteve (Reply 12):
On the B744 it is all to do with the hydraulic systems and the brakes they power.
Not necessarily, from my own observation. Barring dual starts, JAL will do 4-3-2-1, while I have watched Cathay do 4-1-3-2. Recently flew on KLM, and they did 1-2-3-4... go figure. But then, they're Dutch.
I think TristarSteve has the reason for the 747 start sequence. #4 system powers primary brakes, #1 system is the first alternate (#2 is second alternate) . Thus, CX and JA start to give primary brakes, where as KLM starts to get first alternate.
Quoting AA737-823 (Reply 14): And they fly GE's.... with a Pratt, it's a miracle that the thing will spin at all, even with an APU coupled to a ground start cart!
The Aerolineas Argentinas 747 classic I observed starting engines with packs on was powered by none other than the venerable JT9D-7. Whether or not the PW-4000 has vastly different starting air requirements I'm not sure.
Quoting AA737-823 (Reply 14): Again, depends on the airline. I have never seen a carrier do it the way you've described- which leads me only to believe that I've never watched the carrier you're watching.
Given an entirely free choice, most 747 crews at SYD start as I have stated, but it is most certain to be a highly airport and airline dependant procedure, thus my related experiences fall under the same umbrella of uncertainty.
Regards, JetMech
The universe revolves around engineers as we choose the co-ordinate system!
Jetlagged From United Kingdom, joined Jan 2005, 1814 posts, RR: 6 Reply 18, posted (2 months 5 days 9 hours ago) and read 1736 times:
Quoting JetMech (Reply 16): I think TristarSteve has the reason for the 747 start sequence. #4 system powers primary brakes, #1 system is the first alternate (#2 is second alternate) . Thus, CX and JA start to give primary brakes, where as KLM starts to get first alternate.
For pushback it's just as important that you have hydraulic power for the nose wheel and body gear steering systems (hyd sys 1). However, since the 747 has multiple sources of hydraulic power (standby pumps, demand pumps, engine driven pumps) a push or tow can be safely accomplished with no engines running at all. So the engine starting order is as much about tradition as anything else.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
Sponsor Message: 
From Canada, joined Nov 2004, 1008 posts, 
From United States, joined Jul 2007, 1058 posts, 
From San Marino, joined Jun 2005, 1054 posts, 
From Ireland, joined Mar 2004, 3470 posts, 
From Sweden, joined Nov 2005, 2125 posts, 
From Hong Kong SAR, PRC, joined Dec 1999, 5356 posts, 
From Switzerland, joined Oct 2006, 6193 posts, 
From Australia, joined Mar 2006, 1882 posts, 
From United Kingdom, joined Jan 2005, 1814 posts,