I wasn’t really planning on making this a three part series, but based on the response to the two first parts I feel the need to address some of the comments I have received and tidy up a few loose ends, because the big elephant is still in the room.
Why do you have to open the pneumatic crossfeed valves to de-ice the wings? Exactly what does the AC bus cross-tie switch do? And why do the engines only draw fuel from the center tank when all the fuel booster pumps are on? The key to understanding these and many other aspects of your aircraft is studying the schematic drawings for the various aircraft systems. That may sound a little bit dry, but to help you out I have included a Schematics section in the DC-9 Classic Flight Center that gives you live interactive schematic drawings.
Just recently came across an article on the Internet that detailed the differences between the various DC-9 models, as well as the MD-80 series, the MD-90 and B717. I thought it was a very interesting article and I wanted to share it with you.
The cowboy's checklist for the DC-9 Classic, created by Thomas Thurnheer, contains the minimal steps needed to operate the DC-9 Classic. This checklist has been designed for those who like to keep the workload low while starting out flying the DC-9 Classic or for flying online.