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Turn air conditioning off prior to engine star

Featured Replies

Whenever I fly in a 737, I observe the air conditioning is turned off prior to engine start. I imagine this has to do with the pneumatic/duct air pressure to have enough power for the engine start. But what is the real procedure in the overhead panel? What switches these pilots turn on or turn off?Thanks

Teo Halfen

  • Commercial Member

The procedure in the tutorial is the procedure used in the real world...

Kyle Rodgers

packs off start them up! flaps 5 taxi checks!

Vince Lanz

ATP

RW B737 Pilot

Pretty simple. Left and right packs off when starting the first engine. It is possible to start the other engine with the running engine's pack and engine bleed on.

Shane Gavin

  • Author

Ok. When APU is on, if I turn both packs off, duct pressure goes down. So, I use to let the right pack on and the left pack off.

Edited by Lemond23

Teo Halfen

Ok. When APU is on, if I turn both packs off, duct pressure goes down. So, I use to let the right pack on and the left pack off.
It goes down when both packs are off as there is not a demand for bleed air, but when you start the start up process you will see the duct pressure comes back as now there is a engine start demand for bleed air.

-Raven Harris
Intel i7 980X @ 4.43GHz | ASUS Rampage III | Corsair 6GB DDR3 2000MHz | 3 EVGA GTX280 | Corsair 1200 Watt | Intel 510 SSD (RAID 0)
PMDG - 747-400/8iF | MD11/F | BAe J41 | 737NG 6/7/8/9 Hope ER/BBJ|777LR/F
Flight1- Cessna Mustang

 

What Raven says is true. I will add that this is a bit different from both classics, where bleed air extraction was not demand-driven, and a crossbleed start, where you need to observe the pressure and adjust live engine thrust to have at least 40PSI.

--Peter Fabian 
RTFM.jpg

At SWA, I believe the procedure is as follows. Turn off the packs, and start the #2. When that is online, close the isolation vavle, and set the right pack to high. Then, start the #1. Once that is online, you can set the iso valve to auto, and then the packs as desired. Getting the right pack on is for pax comfort.

You are correct ^^^

Vince Lanz

ATP

RW B737 Pilot

  • Commercial Member
At SWA, I believe the procedure is as follows. Turn off the packs, and start the #2. When that is online, close the isolation vavle, and set the right pack to high. Then, start the #1. Once that is online, you can set the iso valve to auto, and then the packs as desired. Getting the right pack on is for pax comfort.
You are correct ^^^
Good to know! I've been flying a lot of SWA since the NGX came out. Now I can sim more accurately.Thanks guys!

Edited by scandinavian13

Kyle Rodgers

You dont have to go to High on the #2 pack, Auto is fine. Also, I only start them like this when it is hot out to cool the passengers down. Otherwise I just turn the packs off, start the engines and congure the bleeds and packs on my before taxi flow.

Vince Lanz

ATP

RW B737 Pilot

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