What happened
On July 8, 2012, at 17:00 local time, a Robin DR400-140B, registered F-GGJU, was taxiing at the Clermont-Ferrand Auvergne aerodrome. The pilot, carrying three passengers, departed from the parking area and began a 3,000-meter taxi toward the runway 26 holding point.
During the taxi, the pilot noted that the aircraft tended to veer toward the left. Despite this, the pilot managed to keep the aircraft centered on the taxiway. The pilot twice queried the passenger in the right seat to ensure their feet were not resting on the rudder pedals, but the passenger denied any contact. Upon reaching the holding point and coming to a stop, the pilot observed smoke emanating from the left main landing gear. The pilot immediately evacuated the passengers and alerted air traffic control. The airport fire services (SSLIA) responded, but the aircraft caught fire before the flames could be extinguished.
The investigation
The investigation focused on the braking system and the physical actions of the occupants. Investigators examined the braking mechanism and found no mechanical malfunction that would have caused asymmetric braking. The rudder pedals were found to be properly articulated at the base, meaning even slight pressure on the upper portion of the pedal would engage the brakes.
While the pilot had conducted a safety briefing prior to departure—specifically instructing passengers on which controls to avoid and outlining evacuation procedures—the investigation considered the physical characteristics of the occupants. The passenger in the right seat was noted to be of large stature.
Findings
- The investigation determined that the inadvertent application of the left brake by the passenger was the primary cause of the incident.
- Due to the passenger's large size, they likely applied pressure to the left brake pedal unintentionally during the relatively long taxi duration.
- The resulting friction caused significant overheating of the left main gear brake, leading to the smoke and subsequent fire.