Incident Overview
Approximately 13 minutes after departure, the aircraft experienced a dual alternator failure. The crew returned to the airport and executed an uneventful landing. During the subsequent taxi to the maintenance hangar, the pilot did not follow the marked taxiway and collided with a ditch.
Airport Construction
Construction was underway at the airport at the time of the incident. The edge of the taxiway was marked with barricades that had lights on top. However, some of the barricades were found knocked down, and the lights on certain barricades were difficult to see from the direction from which the aircraft was approaching.
Sequence of Events
After the uneventful landing, the pilot proceeded to taxi the aircraft toward the maintenance hangar. While doing so, the aircraft deviated from the designated taxiway and entered an area where construction was in progress. The taxiway edge was delineated by barricades with lights, but due to the orientation of the approach and possibly knocked-down barricades, the pilot did not perceive the boundary. The aircraft subsequently impacted a ditch.
Findings
The investigation determined that the pilot failed to follow the marked taxiway, resulting in a collision with a ditch. Contributing environmental factors included the airport construction activity and the reduced conspicuity of some barricade lights from the pilot's perspective.