Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Workload; Troubleshooting; Time Pressure
Aircraft Equipment Problem Critical
Flight Crew Diverted; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Landed in Emergency Condition; General Declared Emergency; General Maintenance Action
Aircraft
During the climb out the First Officer and I heard a relay click about once every ten seconds. It sounded like it was coming from behind the Captain's seat. There were no EICAS messages present at this time. We brought up the electrical page on the MFD and saw that GEN 4 was showing 28V; but 0A and still indicating green; not amber. Generator 2 was carrying the entire load for the right side network. GEN 2 was showing around 28V and 250A. GEN 1 and 3 were around 110-120A. I asked the First Officer to start the APU so we could have another generator available. The APU generator came online and was sharing the load with generators 1; 3; and 2; but GEN 2 always had about double the amperage of the other GEN's. About 5-10 minutes later we started getting the GEN OFF BUS messages for generators 1; 3; 4 and the APU GEN. They didn't all go offline at the same time. We would get a GEN OFF BUS EICAS message for one generator and reset it per the QRH; and it would come back online; but shortly afterwards either the same generator or a different GEN would go offline. During this time when the generators were coming off and on; GEN 2 was always online and; and would initially share the load with the other generators but slowly the amperage would bleed off the other gens and leave GEN 2 as the only generator carrying any amperage. GEN 2 was also showing a voltage of around 33V at this time. I had been talking with Maintenance and Dispatch; and decided it was time to return to the departure airport. After telling ATC that we would like to return; GEN 2 came OFF BUS and the aircraft went in to standby power. We were in level flight at 290-300 KIAS when the airplane went to standby power; opening the nose gear doors. We declared an emergency with ATC and requested a diversion to the nearest suitable airport. I notified the Flight Attendant that we had an electrical emergency and were going to land as soon as possible and to prepare the cabin for landing. I took the controls from the First Officer and asked him to review the QRH for a loss of all generators. During our descent toward the divert airport; we were unsuccessful at getting any of the generators to come back online. As we prepared for our emergency landing; ATC vectored us for an approach to Runway 17; and we were able to perform a visual approach; with Flaps 0. After landing we stayed on the runway and were going to wait for a tug to pull us off the runway and to the terminal. I decided to try and reset the generators; and Generators 1 and 3 came online. The nosewheel steering was working at this point so we taxied to the terminal; parked and deplaned normally at a Gate. There was a mechanic there from another airline who was there waiting for us at the gate and had been informed of the situation by Maintenance Control. We performed a maintenance test of the electrical system at the gate. During the test; GEN 2 would not come online; and there was an EICAS message for GEN 2 OFF BUS. The GEN 2 indication on the MFD was amber; reading around 6-7V and 0A. Other than that; the system was working normally. We taxied the aircraft to the Mechanic's hangar and I noted the discrepancies in the aircraft logbook.
An EMB-135 electrical system began malfunctioning after takeoff and finally only STBY POWER was available so an emergency was declared and the flight diverted to an enroute airport for maintenance.