Air cart usage.

Air cart usage.

Postby AZJim320 » Sun Feb 18, 2018 2:27 pm

I want to talk about when to use the external air cart. I see streamers using this to run a pack on the Flight Factor 757 and 767 as well as the FlyJsim 737, 727 and other aircraft with this option when they have an operating APU. If you have an operating APU and the bleed switch is not on MEL (Minimum Equipment List), there is never a reason to use the external HIGH pressure air cart.
There are two types of air we connect to our aircraft at the gate. There is conditioned air that usually plugs in from the yellow hose you see from the jetway, or could be a portable unit. This is NOT high pressure air! You do NOT use this to run a pack and could never be used to start an engine. This air comes from an air conditioning unit directly to the main supply duct into the aircraft, just like it comes from your vent at home.

The second type of air we can use is the HIGH pressure air from the cart you see as an option on the aircraft I mentioned. This is used when you have an APU, or APU bleed on MEL. We need a high pressure air source to start an engine and with out the APU we need this cart to start. This cart has a narrow high pressure hose. If you have ever been on a flight without an APU you have heard it’s high pitch noise and watched it belching smoke as your flight starts an engine at the gate. Technically you could run a pack with this but the air is not conditioned and could add an oder to the cabin. It is only a last option to use this for a pack.
So we use this air cart to start an engine at the gate when we can’t use the APU. I have noticed most of the sim system manuals discuss this procedure in the supplemental section.. Basically you stay connected to external AC power at the gate. Start the engine on the opposite side the cart is connected. After the engine is started connect the generator and disconnect ground power. Push back and on taxing out you do a cross bleed start. You use air pressure from the operating engine to start the second engine. On the 737 you have to run the power up quite a bit to get the minimum 30psi. Make sure you let ground know so you don’t flip the C172 over taxiing behind you. That’s all I have for now. Cheers,
Jim
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Re: Air cart usage.

Postby FDXDave » Sun Feb 18, 2018 8:02 pm

Thanks Jim. I knew the Air Unit was a high pressure unit which could be used to start the engines. I used this Unit on the 767-300 to start on the CARGO Ramp. I never used the APU on that plane until My approach, so I will still have power upon shutdown. I just Purchased the FF-A320 and this AC too has the high pressure unit. So I only used it to provide air to the packs to provide AC. I notice on this AC that the packs only provide air to the cabin. That only the APU allows the AC to the PAX cabin. But now that I know the Cabin is not actually receiving cold air, I no longer feel the need to simulate this. With this AC, I do try to do things proper and not start the engine while at the gate. This Air unit is very loud even with in cockpit sounds lowered. So thank you for this info. I will no longer be using it lol.
Dave.
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Re: Air cart usage.

Postby AZJim320 » Sun Feb 18, 2018 9:01 pm

Your welcome Dave. As I have said in earlier posts I am really impressed with the level of knowledge in the flight sim community. I thought this is a topic I could bring some real world knowledge and clarification to. I know there are guys like yourself that want to simulate real world procedures.
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Re: Air cart usage.

Postby AZJim320 » Tue Feb 20, 2018 7:03 am

One other piece of trivia. Did you know (Pack) is an acronym? It is Pneumatic Air Conditioning Kit. :)
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