BE400 first officer reported a high generator amperage after starting the second engine causing both...

Narrative:

Aircraft was on ground commencing with engine start. During start sequence; PIC and myself noticed that after initial start; (right engine) the battery was not reducing to the recommended 150 amps very quickly. It did after a few minutes; and we commenced with number one engine start. After number one start; upon selecting start select off; gen 2 pegged on the ammeter. At this point; both generators tripped automatically. Then 'batt only' came online and both engines were cut off by the PIC. After I exited the plane; I observed smoke emitting from the rear of the fuselage. I ran back to the cabin and had every passenger exit the aircraft immediately. Any suspected fire in the plane extinguished on its own without any external fire suppression. After the aircraft was placed in the hangar; upon inspection; maintenance personnel observed a suspected failure of the aircraft mosfet box (electrical transistor) in the tailcone. These components were incinerated to an extreme amount. Also; the right tail horn was burned as well. It is important to note that this beechjet returned to service exactly one month after a lengthy maintenance interval was completed.

Original NASA ASRS Text

Title: BE400 First Officer reported a high generator amperage after starting the second engine causing both generators to trip. The Captain shut both engines down and the passengers were asked to evacuate when smoke was seen coming from the tail of the aircraft.

Narrative: Aircraft was on ground commencing with engine start. During start sequence; PIC and myself noticed that after initial start; (right engine) the battery was not reducing to the recommended 150 amps very quickly. It did after a few minutes; and we commenced with number one engine start. After number one start; upon selecting Start Select off; Gen 2 pegged on the ammeter. At this point; both generators tripped automatically. Then 'Batt Only' came online and both engines were cut off by the PIC. After I exited the plane; I observed smoke emitting from the rear of the fuselage. I ran back to the cabin and had every passenger exit the aircraft immediately. Any suspected fire in the plane extinguished on its own without any external fire suppression. After the aircraft was placed in the hangar; upon inspection; Maintenance personnel observed a suspected failure of the aircraft MOSFET box (electrical transistor) in the tailcone. These components were incinerated to an extreme amount. Also; the right tail horn was burned as well. It is important to note that this Beechjet returned to service exactly one month after a lengthy maintenance interval was completed.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1439949
Time
Date	201703
Local Time Of Day	0601-1200
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	Beechjet 400
Operating Under FAR Part	Part 91
Flight Phase	Parked
Flight Plan	None
Component
Aircraft Component	Electrical Power
Person 1
Function	First Officer
Qualification	Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 35 Flight Crew Total 5036 Flight Crew Type 1495
Events
Anomaly	Aircraft Equipment Problem Critical Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor

BE400 first officer reported a high generator amperage after starting the second engine causing both generators to trip. The captain shut both engines down and the passengers were asked to evacuate when smoke was seen coming from the tail of the aircraft.