Date: 201201
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ramp ZZZ
Aircraft component: APU
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Commercial
Human factors: Training / Qualification; Workload; Distraction; Human-Machine Interface; Situational Awareness; Communication Breakdown; Confusion
Second reporter function: Captain; Pilot Flying
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Ground Personnel; Person Gate Agent / CSR
When detected: Aircraft In Service At Gate
Result: Flight Crew Took Evasive Action; Flight Crew FLC complied w / Automation / Advisory; General Maintenance Action
Contributing factors: Aircraft; Company Policy; Environment - Non Weather Related; Human Factors; Procedure
Primary problem: Aircraft

Narrative: Reaching the ramp; we were directed to a parking line for use with aircraft stairs. No GPU was present. We parked the aircraft and both engines were shut down. When it was apparent we were not going to get a ground power unit (GPU); we initiated an APU start from battery power. The aircraft power flickered badly when the start was initiated. Numerous EICAS messages filled the screen when it came back on; and we observed the APU EGT rising rapidly. One of the ramp personnel outside the Captain's window yelled to get our attention; and gave the fire signal. As we looked back at the EICAS we observed an EGT overtemp and ran the APU FIRE EPC; shutting down the APU. We never received an APU FIRE EICAS message. The Ramper that had signaled us went toward the back of the aircraft; and we attempted to get the attention of other personnel to ascertain if they observed any further indications of fire. We could not get the attention of any personnel; and the Captain had to strobe a flashlight to get someone to come to the window and talk to us. The individual; whom we later found out to be a mechanic; was not aware of what was going on and told us to 'just start it again.' We tried to express our urgency in getting the stairs pushed up to the aircraft so we could open the cabin door and communicate; and a GPU so we didn't drain the batteries and lose all power with passengers on board. I asked the Captain if he wanted me to call Crash Fire Rescue (CFR); he decided it wasn't necessary since we never received a fire message; and the EGT had dropped and did not indicate a fire. Finally; the stairs were pushed up to the aircraft; and we were able to communicate with ramp personnel. If we had received further indication of fire and discharged the APU fire bottle; we still would not have had communication with the ramp; and were discussing the possibility of evacuating out the main cabin and service door without stairs; which certainly would have caused injuries. Ramp personnel informed us they had been trained what to do for engine fires; but not APU fires. The aircraft batteries were clearly unable to perform as expected; despite sufficient voltage indications on the MFD. This may or may not have contributed to a faulty start of the APU; causing flames to exit the APU exhaust pipe. With the indication of fire; ramp personnel should have stopped their tasks and moved away from the baggage compartment of the aircraft; and at least one should have stayed in visual and shouting distance from the cockpit to communicate the continuation of fire; or no further indications. With this kind of emergency; the next task should have been to move the stairs into position to facilitate a potential evacuation of the aircraft.


Second narrative: First Officer read; Captain repeated and pointed to then accomplished after First Officer verification checklist items. No fire or fire detection failure warnings or cautions observed. AOM APU FIRE Checklist reviewed; battery voltage at this point falling below 23.5. No GPU available. Original ramp agent was no longer in view. Two other uniformed employees standing a distance off. Captain attracted their attention with flash light. Captain assumed they were aware of the situation. A conversation in a loud voice was established via window. Some confusion was apparent as to the situation. Evacuation was considered as an evaluation of exterior conditions was made by Captain. Ramp indicated original observation leading to fire signal was from APU exhaust. Passengers were deplaned via stairs and exited the ramp via walkway/to jetbridge toward nose of plane. APU FAIL/ APU failure checklist considered. Some confusion on the ramp to cockpit communications occurred. I was not able to communicate with ramp clearly. No hand signals for preparation for possible evacuation appear to exist. I am not aware of the training that a ramp person gets if an unexpected deplaning/ evacuation occurs. It is difficult to tell by Captain from cockpit if the main cabin door is blocked when stairs are place near door. Due to the thin cockpit wall; it may be possible for people in front of cabin to hear parts of this type of conversation misunderstand and panic or take their own action. The APU FAIL/ APU failure checklist is not clear if it is to be utilized if APU is not acting correctly or only after a complete failure. It does not address a hot start type of situation. A restart; as call for; may cause additional issues if fuel is introduced into a defective system.


Synopsis: An EMB145 APU overheated during start and ground personnel indicated a tail pipe fire but did not established direct communications and as the flight crew completed the emergency checklist they were very confused about the aircraft's status.