I recently downloaded the HJG b727-200fadv_leaps_ntl_vhf_jt8d-17_v2.0 along with the sound and panel for FS9. What a great aircraft! In fact, I've found that all of the HJG planes are great quality. Once in a while you find something that doesn't quite work the way you want, or you need to change something for whatever reason. Well I found that the large cargo door on the port side didn't work after pressing SHIFT+E 1,2,3,4. Only the pilot door worked. After messing around with it for a while I was about to conclude that it just wasn't functional even though the photos clearly showed them open. I remembered on some other aircraft that the doors were tied into other commands such as wing fold, water rudder, etc. As it turned out, the cargo door responded to "Tail hook up/down". I went into Options/controls/assignments/general aircraft commands, and I assigned the tail hook up/down command to SHIFT+F5. After that the door opened and closed perfectly! Also, the latter for the pilot door is under the "Concorde nose & visor up/down" command, Shift+F6 to lower it, and Shift+F7 to raise it. There is an icon already on the panel to operate the stairs at the rear of the fuselage, or you can assign it to the wing fold command using Shift+F8.
Anyway, I hope this saves someone a headache.