23 minutes ago, skelsey said:

It's an air-driven pump, so using the Aux electric pump takes load off the bleed system and provides pressure to Hydraulic System 1 for steering and alternate brakes.

Thanks

Its not enough to set it to Auto then ? The APU would provide bleed air then to the system 1?

 

Thanks

Michael Moe 

 

 

41 minutes ago, Michael Moe said:

Its not enough to set it to Auto then ? The APU would provide bleed air then to the system 1?

No -- in AUTO it will, as you say, run off the APU bleed air thus reducing the overall available duct pressure. The whole point of running the aux electric pump is to reduce the bleed demand on the APU during the start.

The more 'puff' you have available to turn the starter motor the faster the engine will turn over and the less chance there is of a hot/hung start.

1 hour ago, skelsey said:

It's an air-driven pump, so using the Aux electric pump takes load off the bleed system and provides pressure to Hydraulic System 1 for steering and alternate brakes.

Thanks

So when you dont have an AUX option on the System 1 you just leave it at AUTO i guess.

Thanks Michael Moe

On 18/04/2017 at 11:49 AM, Juergen said:

Hi,

I just tried the BA B747 with Rolls Royce engines again:

IRS set to NAV; Hydraulic pumps SET; Fuel pumps ON; Ignition CONTINUOUS; APU ON; Pack 1 Normal; Packs 2 & 3 OFF; duct pressure: 30psi;

Start switch engine # 4: PULLED (does NOT illuminate); duct pressure rises to 51 & 50 psi; engine # 4 bleed valve ON; NO airflow to engine # 4; APU running; continuous ignition ON.

EPR for engine # 4 shows a value of 0.8 (see screenshots)

https://www.flickr.com/photos/141330124@N05/shares/7h7wio

Any help would be appreciated

You should not be putting continuous ignition on. Ignition will be provided by the start system, whether autostart or manual.

Continuous ignition is primarily intended to prevent engine flameout, not for engine starting.

The difference between RR and GE start procedures in this case is due to the lack of  autostart in the DLH configuration. Without autostart the RR engine start would be very similar to GE apart from when the fuel is switched on. 

14 hours ago, Qavion2 said:

 

Do you mean you didn't see duct pressure rising, Rick? Or did you just not look at the duct pressure?

Thanks.

Hi John, from your previous posts, I am aware that you are far more technically qualified that I am, so please forgive me if I do not know all the terms.

If you are referring to the NGT display, then no I did not see anything there, till I flicked that fuel cut-off switch to 'Run'. I'm in the KLM repaint at the moment en route to TNCM, so am not sure if it is a GE-engined version, but I'll come back with a screenshot later in the R-R version.

18 minutes ago, vc10man said:

KLM repaint at the moment en route to TNCM, so am not sure if it is a GE-engined version

KLM would be a General Electric engine variant. You can also tell by looking at the EICAS since the General Electric variant is the only one of the three that doesn't use EPR.

20 minutes ago, Captain Kevin said:

KLM would be a General Electric engine variant. You can also tell by looking at the EICAS since the General Electric variant is the only one of the three that doesn't use EPR.

Thanks Capt Kevin. Yep, can see it now.

 

45 minutes ago, vc10man said:

Hi John, from your previous posts, I am aware that you are far more technically qualified that I am, so please forgive me if I do not know all the terms.

Hi, Rick, I was just trying to confirm that you were also seeing the duct pressure on the ECS Synoptic rising to 50psi (or so) with only the start switch pulled (with Autostart ON). If it doesn't rise, that's normal. If it does rise, we need to call an engineer

Cheers

Just now, Qavion2 said:

 

Hi, Rick, I was just trying to confirm that you were also seeing the duct pressure on the ECS Synoptic rising to 50psi (or so) with only the start switch pulled (with Autostart ON). If it doesn't rise, that's normal. If it does rise, we need to call an engineer

Cheers

Hi John. Told you, you were the ace-of-the base, thanks for that clarification. Recalling from memory, I think I did not see anything in that EICAS synoptic(that's the term I was struggling to find) when I pulled Engine #4 start-switch until I threw that Run switch,

26 minutes ago, vc10man said:

Thanks Capt Kevin. Yep, can see it now.

Yeah, best way to tell apart from looking physically at the engine from outside or looking at the ident page on the FMC, General Electric engines do not use EPR, so the upper EICAS will only display N1 and EGT. Rolls-Royce engines are triple-spool, so they're the only ones to have N3 on the lower EICAS. Pratt & Whitney engines....process of elimination at that point. Those have EPR, but no N3.

Just landed at TNCM. First time flown a 747-400 into there. PMDG have really pulled out all the stops out to make this aircraft a joy to hand-fly into Rwy 10.

Thanks for the info, Capt Kevin. Appreciated.

Further to Simon's reply:

Some original B744's did not have a No1 AUX pump. Where one is fitted then the No.4 AUX pump should always be selected to ON first, otherwise a cross transfer of hydraulic fluid from the No.1 system can occur. When full hydraulic pressure is indicated then the No.1 AUX pump should be selected ON. 

Autostart is normal for engine start up to 6,000ft AMSL (i.e. 4,3,2,1) and is activated when each fuel control switch is selected to RUN,  The APU supplies sufficent bleed air duct pressure (provided you have remembered to set the L & R ISLN and APU Bleed Air switches to ON and all 3 Packs OFF!) to Autostart two engines at a time up to 2,000ft AMSL with an OAT <+36DegC; otherwise the engines are Autostarted one at a time. The main advantage of using Autostart is the fact that whilst it is in control of the start cycle it monitors and takes corrective action for several abnormal starting conditions, such as a hot start or no EGT rise.  It does not monitor for engine oil pressure rise.

Bertie Goddard