What happened
On August 2, 2011, a Robin DR400-180R, registration F-GBUQ, departed from Barcelonnette aerodrome for a flight training session with three passengers. Approximately three to four minutes after takeoff, the pilot observed smoke and flames emerging from the lower right side of the instrument panel. Thick grey smoke quickly filled the cockpit, significantly obstructing visibility and affecting the occupants.
To mitigate the smoke, the pilot partially opened the canopy to provide ventilation. By executing a sideslip, the pilot managed to clear the smoke from the left side of the canopy, allowing for a stabilized approach. The pilot successfully performed an emergency landing on the runway. Once stopped, the pilot closed the fuel selector, released the passengers, and evacuated the aircraft. Ground personnel used extinguishers to combat the fire, which had caused heavy damage to the aircraft. The pilot and passengers sustained slight injuries.
The investigation
Investigators examined the wreckage and identified the fire's origin on the right side of the aircraft near the firewall. They found evidence of melting and heat-induced oxidation on a metal reinforcement tube, which served as a mounting point for an electrical harness containing alternator power and excitation cables. The alternator circuit breaker was found in the tripped position.
The investigation also reviewed the aircraft's maintenance history. While the aircraft had undergone a 500-hour inspection in November 2010, maintenance professionals noted that inspecting the wiring behind the dashboard is extremely difficult without removing the panel. Previous inspections using mirrors were deemed insufficient for a thorough assessment of the entire harness.
Findings
- The fire was caused by an electrical short circuit resulting from an arc between a metal reinforcement tube and a damaged electrical harness.
- Inadequate protection of the wiring harness on its support allowed for insulation erosion through friction/abrasion.
- Maintenance inspections (500 and 1,000-hour intervals) were inadequate for detecting wear on the full length of the cables because they did not require the removal of the instrument panel.
- The pilot misidentified the fire as an engine fire and did not follow the specific emergency procedures for an electrical fire, such as turning off the master switch and the alternator, which allowed the electrical arc to continue feeding the fire.