A DHC8-200 auxiliary invert light displayed at FL210 followed shortly by the smell of an overheated ...

Narrative:

We were at FL210 when we noticed the master caution light illuminate as well as the auxiliary invert light. I called for the checklist for this light. We were starting a descent at this point and after a minute or two of running through the checklist we noticed a faint odor that smelled electrical or like burnt plastic. We told ATC about it and I requested to continue our descent in case the odor increased. We continued the checklist for the auxiliary invert light while we continued our descent to 7;000 ft. The odor got continuously worse so I had the first officer don his oxygen mask and I did the same. At this point we declared an emergency and requested to land as soon as practical. ATC advised us that ZZZ was very close so we decided to divert there. We ran the checklist for smoke in the cockpit even though there wasn't any visible smoke. I quickly notified the flight attendant about the emergency and to prepare the cabin for a normal arrival and that we would be on the ground in five minutes. We did not have enough time to call dispatch to inform them because ATC vectored us right onto a six mile final and we landed without incident. The fire truck was waiting and followed us in to the ramp where we shut down.

Original NASA ASRS Text

Title: A DHC8-200 AUX INVERT light displayed at FL210 followed shortly by the smell of an overheated electrical component. The emergency checklist was used and the flight diverted to the nearest suitable airport.

Narrative: We were at FL210 when we noticed the master caution light illuminate as well as the AUX INVERT light. I called for the checklist for this light. We were starting a descent at this point and after a minute or two of running through the checklist we noticed a faint odor that smelled electrical or like burnt plastic. We told ATC about it and I requested to continue our descent in case the odor increased. We continued the checklist for the AUX INVERT light while we continued our descent to 7;000 FT. The odor got continuously worse so I had the First Officer don his oxygen mask and I did the same. At this point we declared an emergency and requested to land as soon as practical. ATC advised us that ZZZ was very close so we decided to divert there. We ran the checklist for smoke in the cockpit even though there wasn't any visible smoke. I quickly notified the Flight Attendant about the emergency and to prepare the cabin for a normal arrival and that we would be on the ground in five minutes. We did not have enough time to call Dispatch to inform them because ATC vectored us right onto a six mile final and we landed without incident. The fire truck was waiting and followed us in to the ramp where we shut down.

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	1060508
Time
Date	201301
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	Dash 8-200
Operating Under FAR Part	Part 121
Component
Aircraft Component	Inverter
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor

A DHC8-200 auxiliary invert light displayed at FL210 followed shortly by the smell of an overheated electrical component. The emergency checklist was used and the flight diverted to the nearest suitable airport.