Me Again:

APU, Bleed Air, and Hydrolic systems, External Power Carts, Cabin Pressurization systems. Stop the Beech King Air #2 Eng Oil Light from comming on when you pull back on the RPM handels at cruise. The oil pressure DOES stay good.
More realistic failures. IE: Hydrolic pump can shell out ect.
Single landing gear failure.

Allow for up to 10 Engines instead of 4:
ALlow diffrent types of engines:
This wold allow for the B-36 and the KC-97 to both be rendered.
Some KC-97s had 2 turbojets in additon to the 4 props.
REALISTIC stopping abillities and preformances of aircraft.
Have staartup time check local computer time zone and zulu offset.
If its evening in Main, and your flight is takeing off from honolulu, id like it to be afternoon in honolulu when FS opens, not evening. Honolulu time = GMT-10
Allow aircraft lightning strikes from ground or cloud. Let it screw up some avionics.
Id like HF radio capibilite
-Beach