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Paul12

StartEnginesWithNoAPU

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Hello,

 

I tried - not knowing if possible - to start both engines from Ground Connections and Cold and Dark, but without using the APU.

 

Here is what I did :

 

- Select Cold and Dark

- Ground Connections,all on

- Battery : ON

- GRD PWR : ON

On Pneumatic Panel :

- Packs : OFF

- APU bleed : all three OFF

 

Start engine #1: Switch to GRD,Fuel flow : ON

Result : Engine #1 starts after a while

 

Now I tried to start engine #2 using the same conditions as above:

Result: Engine #2 does not start,showing  a message "Start valve open" and "Low oil pressure "

 

Can anybody help/explain ?

 

HubertWerni

 

 

 

 

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The procedure to start engines from external air is as follows:

_ External power connected

_ External air connected (if you need external air but you don't need the air conditioning unit)

_ Batteries on and standby power guard.

_ Fuel pumps on (except center ones if no fuel in the center tank)

_ Hydraulics pumps all on

_ APU bleed off

_ Engine bleeds on (there are no three APU bleed valves but one, the two others are engine bleed valves)

_ Isolating valve opened

_ Pacs off

 

_ Start the engine one with the external air

_ One engine one is running and stable, switch gen1 one and disconnect groung equipement (GPU and external air)

_ Increase RPM on the engine 1 (25-30% N1) to get approx 30psi on the gauge on the pneumatic panel.

_ Start engine 2 using bleed air from engine 1 (cross-bleed start)

_ Once engine 2 is running and stable, swith gen 2 on, set isolating valve to auto and select both pacs on.

 

The external air is used to start only one engine (could be also engine 2 first, but not usual).

 

Your issue comes probably from the isolating valve being closed hence no air going to the engine 2 starter. You can check the air pressure on the gauge on the pneumatic control panel.

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The procedure to start engines from external air is as follows:

_ External power connected

_ External air connected (if you need external air but you don't need the air conditioning unit)

_ Batteries on and standby power guard.

_ Fuel pumps on (except center ones if no fuel in the center tank)

_ Hydraulics pumps all on

_ APU bleed off

_ Engine bleeds on (there are no three APU bleed valves but one, the two others are engine bleed valves)

_ Isolating valve opened

_ Pacs off

 

_ Start the engine one with the external air

_ One engine one is running and stable, switch gen1 one and disconnect groung equipement (GPU and external air)

_ Increase RPM on the engine 1 (25-30% N1) to get approx 30psi on the gauge on the pneumatic panel.

_ Start engine 2 using bleed air from engine 1 (cross-bleed start)

_ Once engine 2 is running and stable, swith gen 2 on, set isolating valve to auto and select both pacs on.

 

The external air is used to start only one engine (could be also engine 2 first, but not usual).

 

Your issue comes probably from the isolating valve being closed hence no air going to the engine 2 starter. You can check the air pressure on the gauge on the pneumatic control panel.

Thank you for your reply.So far  got engine 1 running but after that I am a bit confused,especially how to Start engine 2 using bleed air from

engine 1 ( cross bleed start) . How do I apply this cross-bleed start ?

Thanks again

HubertWErni

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On the pneumatic panel, you have a valve called Isolation valve in between and slightly below the two PACS switches.

That valve must be opened to allow communication between the left and the right air ducts.

 

So to perform a cross-bleed start:

_ Check or set the isolation valve (not "isolating valve" it was a typo) to open

_ Check that both engines bleeds are on

_ Increase rpm on the running engine  (engine 1 in this case) to 25-30% N1 in order to have minimum 30psi of air

_ start the engine 2

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On the pneumatic panel, you have a valve called Isolation valve in between and slightly below the two PACS switches.

That valve must be opened to allow communication between the left and the right air ducts.

 

So to perform a cross-bleed start:

_ Check or set the isolation valve (not "isolating valve" it was a typo) to open

_ Check that both engines bleeds are on

_ Increase rpm on the running engine  (engine 1 in this case) to 25-30% N1 in order to have minimum 30psi of air

_ start the engine 2

Thank you for your help.You suggestion was right,it works.

 

HubertWerni

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