Can I start both engines on Ground Air Cart ONLY?

[davierosoft 13]

Andrea,.....

 

It is bad simulation to program a simulator to reflect operating procedure rather than correct logic and physics.  Likewise if they had programmed the starts so they wouldn't work if the fuel pumps were off (as is often the case in addons).  Procedure says turn the pumps on before starting the engines, but if you don't the engines will start anyway.

 

Kevin, this is the only part I'm 100% with you but:

Let's see some cases:

1) Normal first engine start (eng  1 or 2, is not too much important for the system simulation) Pressure is applied when cart is connected, engine is started, PRESSURE REMAINS (as you want), now, you want to start the engine with the crossbleed, you disconnect the cart and start pushback when, you realize you have a bleed problem, no pressure on it because of a failure. You did not realize it until you remove the cart wich is something wrong.

2) Starting no2) engine first, you technically can, and if you have problems somewhere, you can. The cart tube is long enaugh to be positioned to the ENG 1 side, but the tube will be still connected on the right. It is however still in a safe distance for an idle engine (more than 10ft)

 

It is something wrong to let the pressure remain after the engine start. Bleed cannot be applied when cart is supplying air, and bleed cannot be checked until cart is not supplying air.

The simplest way to solve what is for you a bug is to add a "idle/supply" or "air off/ on" on the CDU or a ground communication. But remember that it will add load to the virtual pilot when starting engine. Load that is unnecessary as it works perfectly as it is.

 

Just to mention, there are a lot of people that try to start an engine with CTRL+E, some other are still writing about parking brake that don't go away (chokes installed), I don't think they will never try to start an engine with the ground cart.

[kevinh 409]

Kevin, this is the only part I'm 100% with you but:

Let's see some cases:

1) Normal first engine start (eng  1 or 2, is not too much important for the system simulation) Pressure is applied when cart is connected, engine is started, PRESSURE REMAINS (as you want), now, you want to start the engine with the crossbleed, you disconnect the cart and start pushback when, you realize you have a bleed problem, no pressure on it because of a failure. You did not realize it until you remove the cart wich is something wrong.

2) Starting no2) engine first, you technically can, and if you have problems somewhere, you can. The cart tube is long enaugh to be positioned to the ENG 1 side, but the tube will be still connected on the right. It is however still in a safe distance for an idle engine (more than 10ft)

 

It is something wrong to let the pressure remain after the engine start. Bleed cannot be applied when cart is supplying air, and bleed cannot be checked until cart is not supplying air.

The simplest way to solve what is for you a bug is to add a "idle/supply" or "air off/ on" on the CDU or a ground communication. But remember that it will add load to the virtual pilot when starting engine. Load that is unnecessary as it works perfectly as it is.

 

Just to mention, there are a lot of people that try to start an engine with CTRL+E, some other are still writing about parking brake that don't go away (chokes installed), I don't think they will never try to start an engine with the ground cart.

Andrea, you aren't making sense to me. You are happy the air pressure disappears after the engine start (even though the cart remains connected) and are trying to justify why it does so. Let's forget the safety aspect and consider the pneumatics alone.  If the ground air is connected it will supply pressure to the duct.  The engine running up to idle does not change this.  In fact it cannot.  If you want to check the engine bleed valve after the first engine started the ground crew must disconnect the cart (or close a valve on air supply).  You can easily simulate that in the NGX by disconnecting the ground air on the CDU page.  It doesn't really make sense to have a ground air connected control and also an air pressure on/off control

 

I have not seen a full flight sim where the ground air simulation behaves like the one in the NGX, including 737 full flight sims. In every case the ground air provides around 40 psi if connected whether an engine is running or not.

 

It's not just a bug for me.  If you read back in the thread you will see I opened a ticket about it with PMDG and they confirmed it was acting incorrectly and they would look at it for SP2.   If PMDG had intended the ground cart pressure to behave in the way it currently does they would surely have mentioned it in the introduction manual, along with all the other unusual features explained there.

[davierosoft 13]

I continue to tell you that works as it must for the automation that the system has.

If you need to disconnect the cart to remove pressure, you are doing something NOT REAL, something that is worst that automatically turning off the air after the first engine.

We are not speaking about an Aircraft system, we are talking about an external cart ant it can be either connected or not, supplying or not or even off or on.

Basically, or PMDG must simulate the entire cart logic, or, it is better as it is as it works as supposed to be used in real life with all the automation needed.

PMDG will look at it, I hope they will add a command to turn air off without disconnecting the cart, or it will be a BUG.

[kevinh 409]

I continue to tell you that works as it must for the automation that the system has.

If you need to disconnect the cart to remove pressure, you are doing something NOT REAL, something that is worst that automatically turning off the air after the first engine.

We are not speaking about an Aircraft system, we are talking about an external cart ant it can be either connected or not, supplying or not or even off or on.

Basically, or PMDG must simulate the entire cart logic, or, it is better as it is as it works as supposed to be used in real life with all the automation needed.

PMDG will look at it, I hope they will add a command to turn air off without disconnecting the cart, or it will be a BUG.

This is an aircraft simulation, not a ground cart or ground crew simulation.  There is nothing on the aircraft side which will shut that pressure off with the cart connected.  So the pressure disappearing is a bug.  PMDG agree it should not do it.  Do other addons have any similar ground air control features?  I don't think so, so why should the NGX have it?  The simplest solution, after fixing the pressure bug, is to retain the controls as is.  Connected means connected and air pressure on, just as for any other addon or any full flight simulator come to that.

 

Boeing procedures talk about disconnecting the ground air after starting Engine 1. There's no mention of shutting the ground air pressure off to check the engine bleed valve before disconnecting.  In fact the flight crew can check that in the aircraft by closing the isolation valve and seeing whether engine 1 bleed provides pressure on the left side.  Having checked that you can safely disconnect the ground air.

 

Edit:

 

I've just checked this on the 747 and the 777X.  On the 747 there is no separate control but you can use ground air to start all four engines if you wish.  On the 777X the behaviour is similar to the NGX but more consistent and logical.  After the first engine start (either 1 or 2) the ground air is disconnected, EICAS and the CDU page reflect this state and the external ground air animation is removed.  Perhaps this was indeed the intention on the NGX, but if so it would make much more sense if the same thing happened (complete disconnection of the ground air, not just loss of pressure).  I still think a second start from ground air should be possible if necessary. Currently it is not possible in either sim.

 

Making the ground air disconnection automatic adds the problem of how to reconnect it if required for a second start.  Surely it's better to leave the connection manual, then you can control it as you want?

[Adam T Lutley 12]

Wow!! Okay folks, the ground cart supplies pneumatic air to the bleed system and the only thing regulating it is a flapper valve. As long as the pneumatic cart is supplying air at a higher pressure than what is available in the bleed manifold (usually zero because the only reason to employ an air start cart to begin with is an inoperative APU) there will always be pressure in the manifold from that ground air source.The primary reason of locating the air start cart on the R/H side of the aircraft has to do with the L1 entry door and the jet bridge, not some technical characteristic of the aircraft. Regards