Narrative:

Aircraft was assigned 6;000 ft when on IFR flight plan. Aircraft encountered trace ice (which was not in forecast as per flight briefing) in IMC conditions and pilot turned on pitot heat. Shortly thereafter; pilot lost primary guidance system (attitude indicator; HSI; airspeed indicator; electronic altimeter and vsi) and autopilot malfunctioned. Pilot reported loss of instruments to center. Plane began descent when instruments lost and autopilot malfunctioned. Pilot then began navigation using secondary instruments. Pilot lost about 600 ft while transitioning to secondary instruments. Pilot then climbed back to assigned altitude center very helpful during incident.

Google
 

Original NASA ASRS Text

Title: A BE35 lost primary guidance systems (attitude; HSI; airspeed; altimeter; VSI) in flight during unforecast icing conditions on and IFR flight plan. His backup ASPEN PFD did provide partial information.

Narrative: Aircraft was assigned 6;000 FT when on IFR flight plan. Aircraft encountered trace ice (which was not in forecast as per flight briefing) in IMC conditions and pilot turned on pitot heat. Shortly thereafter; pilot lost primary guidance system (attitude indicator; HSI; airspeed indicator; electronic altimeter and VSI) and autopilot malfunctioned. Pilot reported loss of instruments to Center. Plane began descent when instruments lost and autopilot malfunctioned. Pilot then began navigation using secondary instruments. Pilot lost about 600 FT while transitioning to secondary instruments. Pilot then climbed back to assigned altitude Center very helpful during incident.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.