B1900D flight crew reported noticing an electrical smell followed by failure of the captain's eadi. ...

Narrative:

[At cruise altitude] I started to notice a light odor of something the smelled like 'a greasy engine room;' but the first officer could not smell it. As I continued to sniff around my eadi flickered out and went black. It was about then that the first officer also noticed an odor. My side of the cockpit began to smell more like melting plastic. I decided the combination of melting plastic odor and failing electrical equipment could be the beginning of a potential fire in the cockpit and decided the safest action was to put the plane on the ground as quickly as possible. The nearest suitable airport that had [required] runway length and fire equipment was ZZZ. I declared an emergency with ATC; requested coordination with ground equipment; coordinated with company to have agents meet us there; and advised dispatch of what we were doing. We landed; and unloaded passengers into the terminal. I think this all worked out as well as it could despite the hassle to passengers. Pilots; ATC; fire department; and station agents all reacted quickly and professionally to a potentially catastrophic problem before it turned into one.

Original NASA ASRS Text

Title: B1900D flight crew reported noticing an electrical smell followed by failure of the Captain's EADI. An emergency was declared and the flight diverted to nearest suitable airport.

Narrative: [At cruise altitude] I started to notice a light odor of something the smelled like 'a greasy engine room;' but the First Officer could not smell it. As I continued to sniff around my EADI flickered out and went black. It was about then that the First Officer also noticed an odor. My side of the cockpit began to smell more like melting plastic. I decided the combination of melting plastic odor and failing electrical equipment could be the beginning of a potential fire in the cockpit and decided the safest action was to put the plane on the ground as quickly as possible. The nearest suitable airport that had [required] runway length and fire equipment was ZZZ. I declared an emergency with ATC; requested coordination with ground equipment; coordinated with company to have agents meet us there; and advised dispatch of what we were doing. We landed; and unloaded passengers into the terminal. I think this all worked out as well as it could despite the hassle to passengers. Pilots; ATC; Fire Department; and Station Agents all reacted quickly and professionally to a potentially catastrophic problem before it turned into one.

Data retrieved from NASA's ASRS site as of July 2013 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	1057430
Time
Date	201212
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Beech 1900
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Component
Aircraft Component	Attitude Indicator(Gyro/Horizon/ADI)
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer Pilot Flying
Qualification	Flight Crew Commercial
Events
Anomaly	Aircraft Equipment Problem Critical Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor

B1900D flight crew reported noticing an electrical smell followed by failure of the captain's eadi. An emergency was declared and the flight diverted to nearest suitable airport.