I CAN'T HEAR THE ENGINE SOUNDS IN FS2000
If you have the Pro version of FS2000, install the optional sounds found on CD #3.
If you don't have the Pro, I have no other ideas for you.
I had this problem and was directed by an online MS Tech to re-install Audio
CODEC files (listed under Multimedia devices in Windows control panel) from
Win98 CD. This enabled missing sounds.