What happened
Two separate incidents involving Apex DR400/140B aircraft resulted in significant fire damage at Rotterdam The Hague Airport. On July 8, 2013, the aircraft PH-SPZ experienced unexpected deceleration and a leftward pull while taxiing after landing. An air traffic controller observed smoke emanating from the left main landing gear, followed by visible flames. The pilot evacuated the aircraft, and the left wing sustained extensive damage.
On July 4, 2014, a second incident occurred involving PH-HLR. While taxiing toward a parking position after landing, flames were observed emerging from the left wing. The pilot and passenger evacuated the aircraft without injury, and the fire was extinguished by airport personnel. In both instances, the fire was concentrated on the left-hand side of the aircraft.
The investigation
The Dutch Safety Board examined the mechanical condition of the braking systems and the structural composition of the aircraft wings. Investigators analyzed engine data, which revealed that significantly more power was required to maintain normal taxi speeds during the flights in question compared to previous operations. This indicated the presence of mechanical resistance.
Technical inspections of the landing gear focused on the brake units, which consist of a disc, a piston, and two brake pads. The investigation also reviewed historical data from the French aviation accident investigation bureau (BEA), which documented at least 21 similar occurrences involving the same aircraft type since 1988, some resulting in the total loss of the aircraft.
Findings
Investigators determined that the heat source for both fires was the left-hand main landing gear brake unit. The friction between the brake pads and the brake disc caused the unit to reach extreme temperatures. This heat was conducted through the metal strut to the point where it met the wing structure.
The wing construction of the Apex DR400/140B utilizes a wooden main spar covered in a synthetic polyester fabric. Because there are currently no fire-resistance certification requirements for such wing covering materials, the combination of wood and non-fire-resistant fabric allowed the fire to develop rapidly. While the exact cause of the continuous braking—whether due to a mechanical defect or operational factors—could not be definitively established, the intense heat from the brake unit was sufficient to ignite the wing structure.
Safety action
To reduce the vulnerability of this aircraft type to such incidents, the Dutch Safety Board has issued a recommendation to the European Aviation Safety Agency (EASA). The recommendation advises the manufacturer to improve the brake unit design to prevent the overheating of the brake disc caused by friction between the pads and the disc.