The noise you're hearing in the Diamond is probably the avionics fan behind the screens...there is one electric gyro in the airplane; the turn coordinator for the rate-based KAP140 autopilot, and it is BEHIND the MFD, so I'm not sure if you'd be hearing it or not.
Also, I believe there's two fans, one behind the PFD/MFD and another in the back behind the seats cooling the AHRS, so if you're hearing it from the back, that's most likely your source.
Your CptSpeaking
Last edited by YourCptSpeaking; 02-05-2008 at 09:23 AM.
Reason: Clarity