Hydraulic Pressure System 1 Fail at Startup

[Guest earendil1234]

Hi all,I have this problem today when I would like to start my 744.I loaded the cold and dark panel as per normal.After that, I turn on the APU, etc.After APU is ON, I would like to switch my Hyd Pump switch, 1,2,3 to ON and 4 to AUTO as usual.But, I get the message on EICAS "Hyd Press Sys 1'I pull up my lower EICAS and check the hydraulic seems like I have low pressure on system 1. There is no active failure nor any armed one. How could I fix this?Thanks!

[CaptEm1 6]

Hi all,I have this problem today when I would like to start my 744.I loaded the cold and dark panel as per normal.After that, I turn on the APU, etc.After APU is ON, I would like to switch my Hyd Pump switch, 1,2,3 to ON and 4 to AUTO as usual.But, I get the message on EICAS "Hyd Press Sys 1'I pull up my lower EICAS and check the hydraulic seems like I have low pressure on system 1. There is no active failure nor any armed one. How could I fix this?Thanks!

HiLook under the Demand selector, Engine driven pump 1 is not turned ON. Either it glitched that way or you forgot to turn it on.And please post with your full name.CaptEm

[Guest earendil1234]

I am sorry that I forget to put my name there.Capt Em, The Engine Demand pump was ON just like for no 2,3,4. I tried to switch it off in order to spool up the pressure at sys 1, but it doesn't work. Apparently when I took the screenshot, I forgot to turn it ON again. So, it doesn't solve the problem...Any other clue, Sir?Regards,Adhika

[CaptEm1 6]

I am sorry that I forget to put my name there.Capt Em, The Engine Demand pump was ON just like for no 2,3,4. I tried to switch it off in order to spool up the pressure at sys 1, but it doesn't work. Apparently when I took the screenshot, I forgot to turn it ON again. So, it doesn't solve the problem...Any other clue, Sir?Regards,Adhika

Hmm, that is strange. Have you loaded the cold and dark flight before with no problems? Also, are you sure the number 1 engine is up and running normally? If you havent done it already, shut everything down completely, and turn it on again following the proper procedures and see what happens. If the problem persists, try booting up the PMDG 747 from the Free Flight with the Fly Now button, and see if the hydralic system is working as it should there. Or start with a Cessna, turn off all systems, then switch to the PMDG 747 while ingame to get a cold and dark cockpit. Report back what you find out.CaptEm

[Guest earendil1234]

Hmm, that is strange. Have you loaded the cold and dark flight before with no problems?

I boot up the PMDG 747 from the free flight with the fly now button and started using the cold and dark panel state given from PMDG to load cold and start cockpit. It has been perfectly normal until today when I want to fly the queen again.

Also, are you sure the number 1 engine is up and running normally? If you havent done it already, shut everything down completely, and turn it on again following the proper procedures and see what happens.

I could not start my engine because sys 1 is not up. I could not pull my ignition switch.

If the problem persists, try booting up the PMDG 747 from the Free Flight with the Fly Now button, and see if the hydralic system is working as it should there. Or start with a Cessna, turn off all systems, then switch to the PMDG 747 while ingame to get a cold and dark cockpit.

I tried with Cessna and it still doesn't work...ThanksAdhika

[CaptEm1 6]

Are you saying you are unable to start up Engine #1? Remember, APU bleed air switch must be ON, Packs 2 and 3 should be turned off during engine start to assure enough bleed air is available, Fuel Cutoff #1 must be in the RUN position and autostart button must be ON in order to start everything up automatically. You should now be able to pull the starter switches and successfully start up the engines.Now, with regards to the Hydralics system I really can't make out what the problem could be unless I'm forgetting something. Make sure the EDP switches are turned ON and the Demand switches are in the AUTO position. If you still got the problem after all that, it might be some corrupted files or something. Try reinstalling and see if that fixes it. Turn off anti virus software and firewalls just to be sure.And one more thing, make sure you try the stuff above without using the C&D cockpit load from PMDG to see if you get the same result.Hope it worksCaptEm

[Guest hangar744]

Hi,give that ADP some air.regards,delcom

[Guest earendil1234]

Now, I know why...The APU Bleed was not on (it is usually on directly from the cold and dark setup).Now can somebody tell me why I cannot have pressure when there is no APU bleed?

[CaptEm1 6]

Now, I know why...The APU Bleed was not on (it is usually on directly from the cold and dark setup).Now can somebody tell me why I cannot have pressure when there is no APU bleed?

Hydraulic system 1 and 4 have air driven demand pumps, so they need bleed air to function.

[Guest hangar744]

Hi,the answer is really simple. System 1 and 4 demand pumps are air driven pumps, hence the name ADP. The massive "motor" that drives the input shaft of this hydraulic pump works on air. The possible sources of air on a 744 are the engines, APU or external air. A running engine or APU does not necessarily supplies air to the pneumatic system. There are a few valves involved as well. The APU has a bleed valve just like each engine. If you want to operate pneumatic equipment you have to make sure the air really gets there. If you have only APU as the air source, you will have to open the APU bleed valve. This will only pressurize the crossover manifold. Only things like Pack 2, cargo heat, water system and cargo smoke detection system will be supplied. At this point your wing isolation valves do not let air to do some work. That's why you get duct pressure zero readings for both sides. Two of these guys...one for each side. If you open the left wing isolation valve, air will rush and pressurize the left pneumatic manifold. Users like leading edge flap PDU 1, 2, 3 and 4, Pack 1, hydraulic reservoir pressurization modules 1 and 2, left WAI get their air from this pneumatic manifold and guess what...hydraulic system no. 1 hydraulic demand pump and its turbine drive gets the air from here as well. So no air means no hydraulic power for system 1 by means of a demand pump. The remaining two pneumatic users, namely the thrust reversers (except PW4000) and NAI are normally supplied by their respective engines. Why normally? Because there is a trick to allow reverse flow through the pylon PRSOV and operate the thrust reverser without starting the engine. The other interesting thing about the left wing pneumatic manifold is the 2 TAT probes are also connected to it for aspiration. No, not for probe heating...that's done by electrical power.The right wing pneumatic manifold is pretty much the same as the left with the exception of the TAT probe supply line. So leading edge flap PDU 5, 6, 7 and 8, hydraulic reservoir pressurization modules 3 and 4, Pack 3, right WAI, and ADP 4 respectively.If there is no air source, or the source is isolated and/or shut off by the wing isolation valve...no supply to users. I'm almost sure the PMDG 744 manuals contain some simplified system schematics. With a little time and effort it's easy to understand the basics of the pneumatic system. On the overhead panel bleed air control module and EICAS ECS page the flow lines are there to help you routing your air from any source to any equipment.Looking at your screen shot one may wonder...how did you manage to pressurize hydraulic system 4? Well it was done by the little guy called AUX ACMP (auxiliary alternate current motor pump) and as its name suggests it is an electric pump. And what about system 2 and 3? Well...those are the ACMP's. They are much bigger pumps but also electrically powered.regards,delcom