krisyyz
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B777 Engine Start-ups

Sat Jun 28, 2008 4:33 pm

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?

Thanks,

KrisYYZ
 
Transpac787
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RE: B777 Engine Start-ups

Sat Jun 28, 2008 6:31 pm

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.
 
Qantas744er
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RE: B777 Engine Start-ups

Sun Jun 29, 2008 4:24 am



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  Smile
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boeing767mech
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RE: B777 Engine Start-ups

Sun Jun 29, 2008 1:37 pm

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
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PhilSquares
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RE: B777 Engine Start-ups

Sun Jun 29, 2008 2:43 pm



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.
Fly fast, live slow
 
flymia
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RE: B777 Engine Start-ups

Sun Jun 29, 2008 5:47 pm



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.

http://www.youtube.com/watch?v=Jz8UORc-1B4
"It was just four of us on the flight deck, trying to do our job" (Captain Al Haynes)
 
Qantas744er
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RE: B777 Engine Start-ups

Sun Jun 29, 2008 8:24 pm



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  Smile

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
Happiness is V1 in Lagos
 
Tristarsteve
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RE: B777 Engine Start-ups

Sun Jun 29, 2008 8:44 pm



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
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RE: B777 Engine Start-ups

Sun Jun 29, 2008 9:02 pm



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?

KrisYYZ
 
CX Flyboy
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RE: B777 Engine Start-ups

Mon Jun 30, 2008 1:43 am

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
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RE: B777 Engine Start-ups

Mon Jun 30, 2008 11:22 am

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.
 
Viscount724
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RE: B777 Engine Start-ups

Mon Jun 30, 2008 10:05 pm



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
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RE: B777 Engine Start-ups

Mon Jun 30, 2008 10:29 pm



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.
 
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jetmech
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RE: B777 Engine Start-ups

Mon Jun 30, 2008 11:23 pm



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
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
AA737-823
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RE: B777 Engine Start-ups

Tue Jul 01, 2008 9:19 am



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.
 
Tristarsteve
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RE: B777 Engine Start-ups

Tue Jul 01, 2008 10:40 am

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.
 
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jetmech
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RE: B777 Engine Start-ups

Tue Jul 01, 2008 10:59 am



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
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
johnclipper
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RE: B777 Engine Start-ups

Thu Jul 03, 2008 3:51 am



Quoting Transpac787 (Reply 1):
At UA, standard 777 procedure is to start up both engines at the same time.

On most of my UA 777 flights (more than I care to remember), engines were started one at a time.
"Flown every aircraft since the Wright Flyer" (guys, if you take this literally, then you need to get a life...)
 
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Jetlagged
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RE: B777 Engine Start-ups

Thu Jul 03, 2008 9:22 pm



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.
 
Transpac787
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RE: B777 Engine Start-ups

Thu Jul 03, 2008 9:43 pm



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.

It's interesting how different airlines can operate near the same airplane quite so differently!! NW always does two at a time. 4/3, then 1/2.

Quoting JohnClipper (Reply 17):
On most of my UA 777 flights (more than I care to remember), engines were started one at a time.

Don't know what to tell you. I get to work with them pretty frequently, and they almost always start both at the same time. I don't remember a case in recent history where they haven't.
 
Qantas744er
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RE: B777 Engine Start-ups

Fri Jul 04, 2008 5:18 am



Quoting AA737-823 (Reply 14):
I am not entirely convinced of this rumor, see as follows:

Never was a rumor... 744 Captain knows better  Wink

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.


Leo  Smile
Happiness is V1 in Lagos
 
PhilSquares
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RE: B777 Engine Start-ups

Fri Jul 04, 2008 7:20 am



Quoting AA737-823 (Reply 14):
am not entirely convinced of this rumor, see as follows:

Not a rumor but fact. I have picked up several new aircraft at Boeing and when they do their flights prior to the C1 flight, it's all 4 at the same time.

Quoting JetMech (Reply 16):
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 JetMech (Reply 13):
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 AA737-823 (Reply 14):
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.

AA737-823, since your profile says you're a line mech at ANC, you should know a few things. First the APU on the 400 is completely different than it is on the classic. Secondly the classic pneumatic system is crap when compared to the 400. It's kind of like comparing a 737-100 to a 737NG, apples and oranges. So, believe it or not those are the facts.
Fly fast, live slow
 
AA737-823
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RE: B777 Engine Start-ups

Fri Jul 04, 2008 1:57 pm



Quoting JohnClipper (Reply 17):
On most of my UA 777 flights (more than I care to remember), engines were started one at a time.

Haha, when United sent a 772 here to Anchorage last fall (diversion, actually) they did dual starts!

Quoting Jetlagged (Reply 18):
For pushback it's just as important that you have hydraulic power for the nose wheel and body gear steering systems (hyd sys 1).

WHAT ON EARTH do you need hydro power to nose gear steering for during pushback? Have you never heard of a bypass pin? No, I am sorry, but you're simply incorrect. A person installs the bypass pin to... ahem... bypass hydraulic power to the nose gear steering system. The body gear steering is only activated in extreme nose gear angles.

Quoting PhilSquares (Reply 21):
you should know a few things.

If you'll read what I wrote right below what you've quoted, you'll see that I am speaking from experience. Your experience tells you that it's a more capable airplane than my experience tells me- that's fine.
But there's no need to get snippy. I'm well aware that the APU on the 747-400 is new- hence it burns so much less fuel. That directly affects me when I am planning how much fuel to upload.
 
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jetmech
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RE: B777 Engine Start-ups

Fri Jul 04, 2008 2:59 pm



Quoting AA737-823 (Reply 22):
But there's no need to get snippy.

I'm really not sure if you intend it, but your language in this thread to several others conveys a significant amount of "snippiness" on your part  Wink .

Quoting AA737-823 (Reply 22):
That directly affects me when I am planning how much fuel to upload.

I never knew it was the mechanics responsibility to decide fuel upload.

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
PhilSquares
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RE: B777 Engine Start-ups

Fri Jul 04, 2008 3:45 pm



Quoting AA737-823 (Reply 22):
If you'll read what I wrote right below what you've quoted, you'll see that I am speaking from experience. Your experience tells you that it's a more capable airplane than my experience tells me- that's fine.
But there's no need to get snippy. I'm well aware that the APU on the 747-400 is new- hence it burns so much less fuel. That directly affects me when I am planning how much fuel to upload



Quoting AA737-823 (Reply 14):
I am not entirely convinced of this rumor, see as follows:

Sorry you feel as though I've been "snippy". I haven't been. But when I have been flying the 400 since 1989 and you tell me I am wrong I do get somewhat peeved. If you think I have been "snippy" I apologize, but you I can assure I have been very reserved.

You don't plan fuel, the Captain does that. That's the problem! You are a line mechanic. A very valuable tool but you are out of the loop when it comes to making decisions. End of story. I suggest you take a step back and re-evaluate your position and move along.
Fly fast, live slow
 
Mir
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RE: B777 Engine Start-ups

Fri Jul 04, 2008 5:13 pm



Quoting KrisYYZ (Reply 8):
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?

They may feel that they'd rather have both pilots focus their attention on one start rather than have them divide it between two. It may also be for standardization across the fleet.

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?

If you're doing a start off of a battery, it's a good idea to start the engine closest to the battery first and then proceed down the line with the ones that are progressively further away. If the battery is on the right side of the fuselage, starting the engines in the sequence you mentioned makes sense.

-Mir
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Jetlagged
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RE: B777 Engine Start-ups

Fri Jul 04, 2008 5:45 pm



Quoting AA737-823 (Reply 22):
WHAT ON EARTH do you need hydro power to nose gear steering for during pushback? Have you never heard of a bypass pin? No, I am sorry, but you're simply incorrect. A person installs the bypass pin to... ahem... bypass hydraulic power to the nose gear steering system. The body gear steering is only activated in extreme nose gear angles.

No need to shout, or to be so sarcastic. Body gear steering is quite likely to be required during a pushback. It is activated by NWS angles greater than 20 deg, not exactly "extreme". You could push without it, but the turn radius would be higher.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
Tristarsteve
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RE: B777 Engine Start-ups

Fri Jul 04, 2008 7:20 pm



Quoting Jetlagged (Reply 26):
No need to shout, or to be so sarcastic. Body gear steering is quite likely to be required during a pushback. It is activated by NWS angles greater than 20 deg, not exactly "extreme". You could push without it, but the turn radius would be higher.

Agreed. I have to push a B777 round a tight S bend at ARN. With MLG Steering pressurised it goes OK, but with the steering INOP the tyres bend and twist in all directions. Looks awful.
 
Qantas744er
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RE: B777 Engine Start-ups

Sat Jul 05, 2008 3:46 am



Quoting AA737-823 (Reply 22):
If you'll read what I wrote right below what you've quoted, you'll see that I am speaking from experience. Your experience tells you that it's a more capable airplane than my experience tells me- that's fine.
But there's no need to get snippy. I'm well aware that the APU on the 747-400 is new- hence it burns so much less fuel. That directly affects me when I am planning how much fuel to upload.

For what 74F operator do you calculate the fuel load as a mechanic? Armchair Cargo?

Leo
Happiness is V1 in Lagos
 
speedbird2263
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RE: B777 Engine Start-ups

Sat Jul 05, 2008 2:19 pm



Quoting Qantas744ER (Reply 28):
Armchair Cargo?

 rotfl   rotfl 
Straight'n Up 'N Fly Right Son ;)
 
tf39
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RE: B777 Engine Start-ups

Sat Jul 05, 2008 11:56 pm

Is the APU on the 744 the same as in the 777 especially given it has the capability to start all four engines at the same time?

Also, I read before that the APU on the 744 cannot be started in flight but I beleive all ETOPS certified planes can have their APU started in flight. For the 777s with the GE90-115 engines, can the engines be started in flight without the assistance of the APU? I.e., would there be enough windmilling action to restart those massive engines if for some reason APU bleed air wasn't available?

Thank you for any replies  Smile
 
Transpac787
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RE: B777 Engine Start-ups

Mon Jul 07, 2008 12:29 am



Quoting TF39 (Reply 30):
but I beleive all ETOPS certified planes can have their APU started in flight.

I do believe it depends on the length of the ETOPS dispatch. I have heard (but don't quote me) that ETOPS-120 can be dispatched with INOP APU's. ETOPS-180 and ETOPS-207 must have operating APU's and they must be able to be started in flight.

Quoting TF39 (Reply 30):
For the 777s with the GE90-115 engines, can the engines be started in flight without the assistance of the APU? I.e., would there be enough windmilling action to restart those massive engines if for some reason APU bleed air wasn't available?

Part of the flight restart checklist is to maintain a certain airspeed or at least an airspeed range, so the windmilling is enough to restart the engine.

The pilots in the Pinnacle CRJ crash some years back were too slow when they attempted restart, IIRC. Ended up crashing in that one.
 
Tristarsteve
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RE: B777 Engine Start-ups

Mon Jul 07, 2008 8:32 am



Quoting Transpac787 (Reply 31):
Quoting TF39 (Reply 30):
but I beleive all ETOPS certified planes can have their APU started in flight.

I do believe it depends on the length of the ETOPS dispatch. I have heard (but don't quote me) that ETOPS-120 can be dispatched with INOP APU's. ETOPS-180 and ETOPS-207 must have operating APU's and they must be able to be started in flight.

The B777 was built for ETOPS. The APU is not required for ETOPS despatch as there are two generators on each engine. The B777 APU has two starter motors, one electric and one air.
Older aircraft that were designed before ETOPS was invented quite often require a serviceable APU for ETOPS dispatch, because the electrical system was not designed to cop with engine failure. Look at the B737. With one IDG inop you lose a whole Main busbar until the APU is running. The B777 has computor controlled load shedding. Lose a generator and loads are shed until the load stabilises, then are restored as power is brought back.

Quoting TF39 (Reply 30):
Also, I read before that the APU on the 744 cannot be started in flight

Boeing saw no need for it, so it can't be done (unless you are very clever with CB tripping etc.)
 
movingtin
Posts: 87
Joined: Sat Oct 21, 2006 1:03 am

RE: B777 Engine Start-ups

Thu Jul 10, 2008 2:25 am



Quoting PhilSquares (Reply 24):
That's the problem! You are a line mechanic. A very valuable tool but you are out of the loop when it comes to making decisions. End of story. I suggest you take a step back and re-evaluate your position and move along.

typical pilot response
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: B777 Engine Start-ups

Thu Jul 10, 2008 6:14 am



Quoting TF39 (Reply 30):
Is the APU on the 744 the same as in the 777 especially given it has the capability to start all four engines at the same time?

It's not the same APU.

Quoting TF39 (Reply 30):
Also, I read before that the APU on the 744 cannot be started in flight but I beleive all ETOPS certified planes can have their APU started in flight.

It was only very recently that ETOPS rules (most of them, anyway) got applied to quads. Prior to that, there was no ETOPS requirement for the 747, hence no requirement to air start the APU.

Quoting TF39 (Reply 30):
For the 777s with the GE90-115 engines, can the engines be started in flight without the assistance of the APU?

Yes. Either by windmill or (if only one engine is down) by taking bleed air from the other engine.

Quoting Transpac787 (Reply 31):
The pilots in the Pinnacle CRJ crash some years back were too slow when they attempted restart, IIRC.

Combination of that plus core lock...they were near full thrust (hot core) and then went to zero at very high altitude (cold out)...the resulting thermal differential locked the engine cores so that there was no chance of a windmill restart.

Tom.

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