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joolsd

questions about start up

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I have just been watching a few videos on NGX engine start up on Youtube. There seem to be a lot of different techniques for start up. I am hoping there are a lot of ways of doing the same thing, but also I guess some of it is wrong.

 

Before start up how should the 4 HYD Pumps be set? People seem to do different things here? Is it a drain on resourses?

 

When starting the engines how high should the N1 be, I noticed on alot of videos that 25% is the choice for ignition. I think I have been starting my engines too low at 20%, maybe thinking of old 737 classic videos. A small thing I guess.


J u l ia n D i a m a n d i s

 

 

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Not 100% sure about the hydraulics, but I think they have to be off due to them controlling the nose wheel steering. I think in the RW it can cause damage to the nose gear assembly if you have the hydraulics on during pushback.

 

When starting the engines, wait for N2 to be above 25 before you turn the fuel control on. Ensure the Air Con packs are off and the isolation valve is open.


voz777_zpsa91dce79.jpg

 

"If you can't solve and equation with calculus, you're not using enough calculus" - A wise friend

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Hi hi,

 

Okies, this is straight from an OEM Operations Manual...

 

Announce engine start sequence. Normal starting sequence is 2, 1.

 

Call “STARTING ENGINE No. ___.” Position ENGINE START switch to

GRD.

 

Verify increase in N2 RPM.

 

Verify increase in oil pressure by the time engine is stabilized at idle and call “OIL PRESSURE RISING” when observed.

 

Position engine start lever to IDLE detent when:

• N1 rotation is observed and

• N2 RPM reaches 25% or

(if 25% N2 is not achievable)

• at max motoring and a minimum of 20% N2. Max motoring occurs when

N2 acceleration is less than 1% in approximately 5 seconds.

 

Verify fuel flow and EGT indication.

 

[Without automatic ignition]

At 56% N2 RPM check ENGINE START switch moves to OFF; if not, position start switch to OFF.

Verify START VALVE OPEN alert extinguishes as the ENGINE START switch moves to OFF and report “STARTER CUTOUT.”

 

[Automatic ignition] At 56% N2 RPM check ENGINE START switch moves to AUTO; if not, position start switch to AUTO.

Verify START VALVE OPEN alert extinguishes as the ENGINE START switch moves to AUTO and report “STARTER CUTOUT.”

 

Monitor N1, N2, EGT, fuel flow and oil pressure for normal indications as the engine accelerates and stabilizes at idle.

 

 

For the before start checklist, regarding Hydraulics, this is what is entered...

Captain.....

Hydraulics .................................................................................... Normal

Note: Alert ground personnel before pressurizing hydraulic

system.

System A HYDRAULIC PUMPS switches – ON

System B HYDRAULIC PUMPS switches – ON

Electric pump LOW PRESSURE lights – Extinguished

Brake pressure – 2800 PSI minimum

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For the before start checklist, regarding Hydraulics, this is what is entered...

Captain.....

Hydraulics .................................................................................... Normal

Note: Alert ground personnel before pressurizing hydraulic

system.

System A HYDRAULIC PUMPS switches – ON

System B HYDRAULIC PUMPS switches – ON

Electric pump LOW PRESSURE lights – Extinguished

Brake pressure – 2800 PSI minimum

 

Does this mean all four switches.....ENG 1 and ELEC 2 -

ELEC 1 and ENG 2 are ALL on before start?


J u l ia n D i a m a n d i s

 

 

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Does this mean all four switches.....ENG 1 and ELEC 2 -

ELEC 1 and ENG 2 are ALL on before start?

 

Yes, otherwise, you would not see the LOW PRESSURE lights for the ELEC PUMPS extinguish.

 

 

Oliver Branaschky


Oliver Branaschky

 

hrdk65U.jpg

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The engine driven pump switches are in the on position before start.

Once ready to start, fuel pumps on and fuel checked, and the A/C packs are to off position, and start air pressure is ready,

you can start the electric pumps are on, so all 4 are in the on position, ready to continue,

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The engine driven pump switches are in the on position before start.

Once ready to start, fuel pumps on and fuel checked, and the A/C packs are to off position, and start air pressure is ready,

you can start the electric pumps are on, so all 4 are in the on position, ready to continue,

 

Ok thanks. I always have the packs off, on start.


J u l ia n D i a m a n d i s

 

 

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The EDP (Engine driven pump) switches MUST be in ON position for most of the time, for Hyd A system elec and eng pump must be switched off in case of pushback made without using the steering bypass pin. But, also this should not apply for the EDP if the engine is started after the pushback procedure.

EDP switches power a depressurizing solenoid wich is normally unpowered (ON) and will be powered and remains powered when the switch is set to OFF. This means that the solenoid could be damaged if the switch is left too much time to the OFF position.

There is no reason to unpressurize the EDP pumps for engine start, also because before engine start, the elec pumps are already on. The only reason is for pushback, in case of no maintenance people and bypass pin presence. In the other cases the pumps can be on as there is no problem in starting.


Regards

Andrea Daviero

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