Confronted with multiple electrical anomalies for which there were no ameliorative checklists; a B717 flight Crew declared an emergency and diverted to a nearby airport.
Synopsis
Confronted with multiple electrical anomalies for which there were no ameliorative checklists; a B717 flight Crew declared an emergency and diverted to a nearby airport.
Narrative
We were cruising at FL300. We started experiencing uncommanded changes to our FMA's (Flight Mode Annunciators) followed by flickering DU's (Display Units). Shortly thereafter our master cautions lit up and numerous alerts were displayed at one time (19). Obviously we had a major electrical malfunction. Both the Captain's and First Officer's Nav displays lost map information and the Captain's FMC locked up. Selecting various synoptic displays revealed many 'X'ed out symbols.We used the QRH to address some level 2 alerts; but this was no help. We notified ATC that we were unsure of our navigation capability and requested radar vectors while we tried to pinpoint the problem. We also began requesting possible alternate airports that had good weather nearby. Since I was not sure of the extent of damage to the electrical system. I began to fear some of the worst case scenarios (loss of all DU's; electrical smoke; fumes; fire; etc). Due to its close proximity; good weather and facilities; I made the decision to divert to ZZZ. ATC was very accommodating and immediately honored my request for descent and radar vectors and an emergency was declared. We were told to expect a visual approach. I requested about a 20 mile final in order to have sufficient time to insure the aircraft could be properly configured for landing. The aircraft did configure normally and we touched down smoothly following the visual approach. The landing weight was slightly above maximum (approximately 1300 lbs). Fire trucks on the scene did not notice anything unusual externally and we proceeded to the terminal ramp for parking. Initially we had no idea what caused such a major malfunction. Mechanics were flown in later that night to work on the aircraft. We reported the next morning to ferry the aircraft; and met with the mechanics. They told us that they replaced the left PCDU (Power Conversion Distribution Units) and the EPCU (Electrical Power Control Unit). That seemed to explain why we couldn't determine exactly what we had lost; since there is no alert or QRH procedure for a PCDU failure.
Second reporter narrative
The Captain was flying. We were cruising along at FL300 and the heading; airspeed and altitude would go into manual mode. The Captain would re-engage the Nav; FMS speed and Performance. The airplane did this a few times; then we got a master caution light and about 15-20 annunciators came on. We got out the QRH and tried going through a few of the problems. Nothing could be resolved. I tried contacting Dispatch and Maintenance but could not reach anyone on the radio. The only way I could communicate was through ACARS on my FMS. The Captains FMS was not working. We were unsure of what navigation systems were working and what faults that were listed were actually true. Two annunciators said Bleed air fault 2 and Sel Cab Press Man; but the cabin was holding and pressurizing. We had a Column Disc also; but the controls worked fine. That is just a few of the master cautions displayed. We were unsure what the problem was and if it would get worse. At that point we decided to divert somewhere VFR. The Captain talked to ATC; while I was trying to reach Dispatch and determined that ZZZ was close by and VFR. The Captain briefed the Flight Attendant's and the passengers. On the way to ZZZ I could tune NAV and ILS frequencies on my side. We had no moving map on either side. We also were not sure if we would get any flaps or gear or if there would be indications of there position. As we configured for the landing we did have a positive gear and flap indication. Here is a list of annunciators: APU fault; Bleed air fault 2; Sel Cab Press; Man; Fuel Qty Sys Fail; Column Disc. On the Status Page there was FCC fail; Airdata 1 Fail; VIA fail; DCU fail; ATC XPDR 1 Fail; GPWS Fail; Vor 1 Fail; GPS 1 Fail; Stall Warn Fault; PSOV fault; FLT REC fail; ILS 1 Fail; DME 1 Fail. The event occurred because of an electrical problem with the airplane.Some training on events like this would be helpful. We really didn't know what caused all the failures and if more failures were to come.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.