Date: 201507
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: Rain
Light: Daylight
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: APU
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Ground Personnel
When detected: Aircraft In Service At Gate
Result: Flight Crew Overcame Equipment Problem; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: After a normal landing; we began our taxi to a remote gate; no jet bridge (passengers must deplane then walk from the ramp to the terminal). We started the APU (Auxiliary Power Unit); which started normally and ran normally. After the APU had been running; we received the EICAS (Engine Indication Crew Alerting System) message 'APU GEN OFF BUS.' We then reset the APU generator; per the QRH. There was no indication in the logbook of previous APU issues; and during the entire day up until this point; the APU had been operating without any issues of any sort.I did not know if the station had an adequate GPU (Ground Power Unit) readily available; and I was concerned about passenger and ramp personnel's safety with an engine running at the gate in this situation. Given these facts; I then completely shut down the APU. After the APU was completely shut down; I then re-initialized the APU control and made sure the APU had been off for at least 1 minute. We then re-started the APU; which started normally and safely.At this time; I shut down engine 1. When I shut down engine 1; DC BUS 1 disconnected from the system. I knew that it was DC 1 because the PFD 1 (Primary Flight Display) and MFD 2 (Multifunction Display) went black; and on the EICAS several components associated with DC 1 came offline as well. While on the phone with Maintenance Control; and as we had begun to deplane; ramp notified me that there was smoke or fire coming from the rear of the aircraft. There was no fire bell; master warning; or red indications on the overhead panel.At this time; I immediately instructed my FA (Flight Attendant) to evacuate the aircraft and to get everyone clear of the ramp and safely away from the aircraft. My First Officer and I then began to initiate an emergency evacuation via the Quick Reference Checklist. As we performed the emergency shut down; I noted that the Cargo Door was open. Because I had no indication of a cargo fire; and because I was concerned about discharging halon onto ramp personnel; I pulled both Fire T-Handles; pressed the APU fuel shutoff valve; and discharged the APU fire bottle. With the last passengers off the aircraft; I then instructed my crew to evacuate; grabbed the portable fire extinguisher in the cockpit; and went to the back of the cabin to search for any passengers and investigate any source of fire. There was no smoke or indication of fire in the cabin.After this; I ran outside to the back of the airplane with the fire extinguisher to make sure that all ramp personnel were clear and there was no fire in back. When I investigated the empennage; the only damage to the aircraft was on the intake to the APU.Once I knew that everyone was safe; I called dispatch to notify them of what had happened; and coordinated with CFR (Crash Fire Rescue).Speaking with a Mechanic later; I was told that there was no damage to the APU itself; or the Fire Loop on the APU. The fire was contained in the intake; which the Mechanic likened to a back-fire. He explained that this was the reason there was no indication of fire in the cockpit; and that he had heard of this type of back-fire happening before.


Second narrative: Landed and taxied to gate; on the ramp we attempted to start the APU (Auxiliary Power Unit). It started normally and ran for a bit; then an APU GEN OFF BUS message appeared. We ran the QRH and reset the GEN. We asked for a GPU (Ground Power Unit). We tried to start APU again and it ran normal. Engine one was then shut down and a DC 1 Bus failure happened. We began to deplane; then ramp notified us of a fire in the back of the plane; at that point we shut down number 2 engine and started the emergency evacuation checklist. Everything turned out safely.


Synopsis: EMB145 flight crew experiences an APU fire after parking on the ramp with both engines and the APU running. The APU generator would not come on line then a ramp person reported that the APU was on fire. There was no fire warning but the APU was shut down and the fire bottle was discharged and the passengers evacuated.