What happened
The aircraft was operating under instrument flight rules during a cruise phase of flight when a critical electrical system failure occurred. At the time of the incident, the right alternator was already inoperative, placing additional load on the remaining electrical components. The left voltage regulator subsequently failed, resulting in an overvoltage condition within the electrical system.
This electrical surge ignited a fire within the aircraft's systems. The crew successfully extinguished the fire, allowing them to continue the flight to their planned destination. However, the failure necessitated flying without the use of communications or navigation equipment for the remainder of the journey. Upon arrival, repairs were conducted to address the damage.
The investigation
The investigation focused on the sequence of electrical component failures that led to the fire. Examination confirmed that the left voltage regulator was the primary point of failure after the right alternator had already been removed from service. The overvoltage generated by this single regulator failure was identified as the direct cause of the ignition.
Findings
The contributing factors included the inoperative right alternator and the subsequent failure of the left voltage regulator. The lack of redundancy in the electrical system meant that a single point of failure resulted in a catastrophic overvoltage event. The crew's ability to extinguish the fire and navigate without standard equipment allowed for a safe landing, though the aircraft required significant repair upon arrival.