Small Transport; Low Wing; 2 Recip Eng
Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Confusion; Distraction
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Aircraft Aircraft Damaged; Flight Crew Returned To Departure Airport; Flight Crew Landed in Emergency Condition; General Maintenance Action
Aircraft
Departed ZZZ runway 30L without incident with 7 passengers aboard. Approximately 15-20 miles north of ZZZ; in cruise at 6;000 MSL; I looked out the left window to inspect the wing for icing. I noticed at that time the flashing red of the underbelly beacon reflecting off the engine cowling and wing; but also noticed irregular flashing patterns of white; yellow; and orange. Upon shutting off the beacon; the yellow; orange; and white flashing remained. These appeared consistent with fire; which I assumed was the case; although I was unable to determine the source of the potential fire. I notified approach that I needed to return to ZZZ; they cleared me direct; then I advised a potential engine fire. Upon landing on 12R; was met at taxiway Q by the fire team; who indicated they did not see any indication of fire. At that time I determined an emergency evacuation would not be necessary. The fire team followed me to the gate; where [the first officer] deplaned the passengers. I deplaned and met with fire personal to inspect the aircraft. We did not find any physical evidence of fire; but we did notice the tail NAV light had become unattached from its assembly during flight and was hanging by wires. In addition; the fire personal indicated verbally that they could smell a strong smoke smell; as did [the first officer] upon arriving at the aircraft; as could I when I deplaned. There was no such smell in the cockpit or cabin.
The Captain of a regional air carrier reported seeing flashes of light outside his window; consistent with a possible aircraft fire. He quickly coordinated a return to the departure airport with Air Traffic Control; where an uneventful landing was accomplished. A post flight inspection revealed a navigation light which had become detached.