Narrative:

[We were] at cruise altitude 12;000 ft given instructions to descend to 11;000 ft. As I dialed in the altitude in the altitude selector yaw damper and autopilot disconnected. Both first officer and captain eadi (electronic attitude display indicator) showed red FD and red RA flags. No power to mfd and transponder. I hand flew aircraft down to 11;000 ft; while first officer started checklist searching for enp checklist. No checklist for red FD. I transferred the aircraft over to first officer no circuit breaker noted tripped at this time. We noted red shark on RMI so inverter checklist complied with inverter switched to #2 with no changes noted. I advised ATC that we needed to contact our company and needed delayed vectors at present time. I wanted to see if dispatch wanted an air return. We had 1950 on fuel on board. We then lost weather radar and ADF. We had a small cell off the right side of aircraft; advised ATC that we needed to stay to the left of our area and that we lost weather radar onboard. When first officer went to adjust power 10-15% tq we received a master warning of configuration. I discussed with first officer that it might be due to loss of radar altimeter. We canceled the warning. I noted that the left avion circuit breaker was tripped. I reset and [it] immediately tripped again. I was still unable to contact dispatch over company frequency and commercial radio so I asked ATC to contact our company and gave phone number. While talking to company ATC asked for souls on board and fuel remaining. Dispatch advised us to continue to our destination. We asked for vectors for the approach. I placed my side on drive-xfr for ahrs failure. The first officer was still pilot flying and while on vectors for the approach ILS first officer GS was intermittently flashing off screen. No flags or erratic indications no white dots on right side of eadi. I then advised first officer that I would take the controls back and fly the ILS on standby instruments. I had good signal on standby. Earlier in the day taws (terrain awareness warning system) was deferred and with erratic GS signal I felt that it was safer to use standby signal since no backup of taws warning with ground. Controls were transferred and ATC was notified. I did ask ATC if they had declared emergency since asked souls on board and they replied that they have everything taken care of. We broke out of the clouds at 800 feet and had runway in sight; landed without further incident. During the entire event we received no master cautions for elect or avionics. Dispatch and maintenance notified on ground. Avionics failure causing FD and autopilot to fail and with previous taws write-up and first officer glideslope not operating properly I chose to fly the aircraft with the stby localizer. ATC declared the emergency due to the priority handling and reports of loss of equipment.

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Original NASA ASRS Text

Title: SF340 flight crew in cruise flight experienced an AHRS failure followed by multiple other avionics anomalies; they continued to their destination without incident after ATC declared an emergency for them.

Narrative: [We were] at cruise altitude 12;000 FT given instructions to descend to 11;000 FT. As I dialed in the altitude in the altitude selector yaw damper and autopilot disconnected. Both First Officer and Captain EADI (electronic attitude display indicator) showed red FD and red RA flags. No power to MFD and transponder. I hand flew aircraft down to 11;000 FT; while First Officer started checklist searching for ENP checklist. No checklist for red FD. I transferred the aircraft over to First Officer no CB noted tripped at this time. We noted red shark on RMI so inverter checklist complied with inverter switched to #2 with no changes noted. I advised ATC that we needed to contact our company and needed delayed vectors at present time. I wanted to see if Dispatch wanted an air return. We had 1950 on fuel on board. We then lost weather radar and ADF. We had a small cell off the right side of aircraft; advised ATC that we needed to stay to the left of our area and that we lost weather radar onboard. When First Officer went to adjust power 10-15% Tq we received a master warning of CONFIG. I discussed with First Officer that it might be due to loss of RADAR Altimeter. We canceled the warning. I noted that the L Avion CB was tripped. I reset and [it] immediately tripped again. I was still unable to contact Dispatch over company frequency and Commercial Radio so I asked ATC to contact our company and gave phone number. While talking to company ATC asked for souls on board and fuel remaining. Dispatch advised us to continue to our destination. We asked for vectors for the approach. I placed my side on Drive-XFR for AHRS failure. The First Officer was still pilot flying and while on vectors for the approach ILS First Officer GS was intermittently flashing off screen. No flags or erratic indications no white dots on right side of EADI. I then advised First Officer that I would take the controls back and fly the ILS on standby instruments. I had good signal on standby. Earlier in the day TAWS (Terrain Awareness Warning System) was deferred and with erratic GS signal I felt that it was safer to use standby signal since no backup of TAWS warning with ground. Controls were transferred and ATC was notified. I did ask ATC if they had declared emergency since asked souls on board and they replied that they have everything taken care of. We broke out of the clouds at 800 feet and had runway in sight; landed without further incident. During the entire event we received no master cautions for elect or avionics. Dispatch and Maintenance notified on ground. Avionics failure causing FD and autopilot to fail and with previous TAWS write-up and First Officer glideslope not operating properly I chose to fly the aircraft with the STBY LOC. ATC declared the emergency due to the priority handling and reports of loss of equipment.

Data retrieved from NASA's ASRS site as of April 2012 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.