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Guest Emile Bax

737NG engine start

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Guest Emile Bax

Hi everyone,While the engine is spooling up after selecting the engine start switch to GND, at what N1 reading is the engine start lever moved up from cutoff to idle ? I know that for the B763 it's done at 18% N1 but suspect that for the 737NG this figure is different and I couldn't find it anywhere in the docs (or on this Forum unless I used wrong keywords). TVMIA for any help.Cheers,Emile.

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Hi Emile,I assume you are talking N2 values here as N1 never reaches 18% during motoring. For the NG I think it is 25% N2 or max motoring. I know this is hard to reach with the PMDG NG so I usually open the fuel at 22-23% N2 or 1.6-1.8% N1.Hope it helps,


Mats Johansson
PMDG Flight Test Dept
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I use the same value as Mats. Max motoring in the PMDG seems to occur at about 23% N2. It should be noted, however, that this information is available in several places in the documentation that comes with the PMDG.


Dave Paige

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Guest robfather

I usually use 20% to move to idle. Read in one of the 737 manuals somewhere that this is the norm.Rob

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>I usually use 20% to move to idle. Read in one of the 737>manuals somewhere that this is the norm.>According to the real-world Continental Airlines Flight Manual for the 737 series (2219 pages worth), for the NGs the start procedure is to wait until 25% N2 or max motoring, whichever occurs first.


Dave Paige

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Guest Emile Bax

Many thanks to all of you who took the time to reply and apologies for obviously overlooking some info in the docs. I thought I'd read them carefully enough but that's what happens when you get to my age *:-* Cheers,Emile.

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Hey there guys. In the NG it is like you guys say. minimum 25% n1 or max motoring and for those who do not know what max motoring is it is when the N2 has reached its limit of 1% every one second and a MINIMUM of 20%. No lower than 20% do you raise the lever. The new software in our NG's supposedly will not dump the fuel in early even if we did raise the fuel lever at even 10% but we dont test this theory and we still raise it as per manual.Jack

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Guest trigger2006

hi emile please try the following am going to to from dark to starting up apu start.step1: turn the battery on step2:apu belled swithch is off step3:fuel on step4:apu to start step5: when the light goes on press the two apu switch on step6:apu bleed on (is what you are not doing in step6)engine start step1: hyd A off step2: hyd B on step3: anti collison light onstep4 both pack off step5:isolation vauve auto step6:engine fuel knob to both to open step7:now switch the engine 1 to GRD step8:and put the engine 2 to GRD

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Hi, I can confirm that the previous poster is correct, although when we start the engines on the line it is slightly more complicated. The reason HYD A pumps are turned off is to prevent damage to the nose wheel steering system during pushback, although Boeing only recommend turning off A pumps.The start sequence in my airline on the line, is to start the clock, turn the related engine start switch to ground, there is a call when N2 increases, Oil Pressure increase and N1 increase. We then move the start lever to the idle detent at 25% N2 or max motoring, the starter value usually closes aroung 56% N2 and then we confirm the engine is stable via 2-4-6-3, N1 20%, EGT around 400C, N2 60% and 300kgs (0.3) of fuel. These are only estimates. We are also monitoring the engine throughout the start sequence for any potential problems, such as a hot start. I'm not sure if PMDG have modelled this but during the start sequence there is a EGT red indication on the outer scale during start up, if there was a rapid increase in EGT towards this value we would manually close the start lever to prevent damage to the turbines. The EEC will also automatically shutoff fuel once the limit is exceeded, this is a feature as with all EEC engine start protection that is only applicable on the ground. In the air there is no start protection so we have to carefully monitor the instruments in the event of an inflight start.I hope this helps,James

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Just to add confusion to the mix at my Airline we do not turn the hydraulics off of the start. We use the 25% or maxmotoring but not less than 20% N2 for moving the start lever and since 2-4-6-6 since we use pounds. Our start configuration is:Packs offIsolation Valve openStart #2 firstAfter start Isolation Valve closedRight Pack on. Now passenegers get some airconditoningStart left engineAfter start left Pack onIsolation Valve AutoAPU Bleed close.We formerly just started #1 then #2 but when fuel prices started to climb they wanted us to do single engine taxi more and came up with this procedure. The Airline my brother works for uses the same procedure.


Tom Landry

 

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Guest Emile Bax

Hi all,Thanks so much again for all your helpful info ! I really appreciate it :-beerchug .Now one more question this has raised if I may :Starting the clock : Where on the 2D panel for the 738 do I find the clock ? I just can't spot it - unless I'm having another senior moment :-shy Cheers,Emile.

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Guest trigger2006

hi i havent got 737-800 i got the 600-700 and it is in when you press shift +3 and in the bottom left corner it is there i dont know if it is the same on the 800 let me know how it goes martin

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Guest Emile Bax

Hi Martin,Your hint didn't work but it DID put me on to finding the solution, which turned out to be embarrassingly simple *:-* Thanks so much for taking the trouble to reply ! :-beerchugCheers,Emile.

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"I can confirm that the previous poster is correct, although when we start the engines on the line it is slightly more complicated. The reason HYD A pumps are turned off is to prevent damage to the nose wheel steering system during pushback, although Boeing only recommend turning off A pumps."Are there NG's without steering lockout systems? I thought this was only on very old classic 737's??? (or is this only to maintain fleet commonality?)Thanks.Q> イアン

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