A beechcraft model 99 flight crew reported a fire indication in the left engine; resulting in an in ...

Narrative:

All operations were normal until we had an indication of an engine fire warning in flight. During cruise flight at 9000 ft. MSL while flying through light rain; the left t-handle; indicating a fire; illuminated. At that point my trainee (pilot flying) performed the immediate action items per our checklist. The light remained illuminated past 20 seconds. I decided we should [advise ATC] and perform an engine shut down. I [advised] ATC and planned to land at ZZZ. I notified dispatch of my decision over company radio. My trainee completed the engine shut down under my supervision. Once we were established on [the] ILS runway xxl at 2000 ft. And 5 miles from the final approach fix; I took controls of the airplane and landed. The reported ceiling was 6000 ft. Overcast. We had the airport in sight 5 miles out; at zzzzz. There were no other indications of a fire throughout the event. I believe rain caused the plane to have a false indication of a fire. The trainee verbally identified the fire handle illumination as I saw it and continued with the engine fire warning in flight memory items and checklist.

Original NASA ASRS Text

Title: A Beechcraft Model 99 flight crew reported a fire indication in the left engine; resulting in an in flight engine shutdown and diversion.

Narrative: All operations were normal until we had an indication of an engine fire warning in flight. During cruise flight at 9000 ft. MSL while flying through light rain; the left T-Handle; indicating a fire; illuminated. At that point my trainee (Pilot Flying) performed the immediate action items per our checklist. The light remained illuminated past 20 seconds. I decided we should [advise ATC] and perform an engine shut down. I [advised] ATC and planned to land at ZZZ. I notified Dispatch of my decision over company radio. My trainee completed the engine shut down under my supervision. Once we were established on [the] ILS Runway XXL at 2000 ft. and 5 miles from the final approach fix; I took controls of the airplane and landed. The reported ceiling was 6000 ft. overcast. We had the airport in sight 5 miles out; at ZZZZZ. There were no other indications of a fire throughout the event. I believe rain caused the plane to have a false indication of a fire. The trainee verbally identified the fire handle illumination as I saw it and continued with the engine fire warning in flight memory items and checklist.

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	1684570
Time
Date	201909
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Aircraft 1
Make Model Name	Airliner 99
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Turbine Engine
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Instrument Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying Check Pilot
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Events
Anomaly	Aircraft Equipment Problem Critical

A beechcraft model 99 flight crew reported a fire indication in the left engine; resulting in an in flight engine shutdown and diversion.