What happened
On July 30, 2014, at approximately 09:15 local time, an RV-10 aircraft, registration SP-YZT, was taxiing at Warsaw-Babice Airport (EPBC) for a planned flight to Kołobary-Bagicz. The aircraft, operated by Invest Sp. z o.o., had recently completed pre-flight inspections and engine start procedures.
During a 90-degree right turn on taxiway D1/B2, the pilot noted that the right brake required more pressure than usual to execute the turn, leading him to suspect a malfunction. While attempting to continue taxiing toward apron 1Z, the pilot was alerted by ground personnel that a tire was on fire. Upon inspection, black smoke was visible trailing from the trailing edge of the right wing. The pilot immediately ordered the passenger to evacuate, shut down the engine, and cut off the fuel supply. Both occupants exited the aircraft safely. Although the pilot attempted to use an onboard fire extinguisher, the fire continued until airport fire services arrived to extinguish the flames and cool the landing gear.
The fire caused significant damage, including a destroyed wheel fairing, a burned tire, damage to the landing gear strut fairing, and deformation of the right wing's lower skin and flaps.
The investigation
The PKBWL investigation focused on identifying the source of the flammable material and the ignition source. Investigators performed meteorological and fire experts' analyses. The investigation established that the aircraft's fuel tanks had been filled to capacity. Because the fuel tank vent lacks a check valve, fuel had escaped through the vent during taxiing.
Due to the aircraft sitting on the apron for 30 minutes in high ambient temperatures, the landing gear and wing surfaces had been heated significantly by solar radiation. The investigation tracked the path of the fuel, noting that it flowed from the vent, down the landing gear strut, and through a gap into the right wheel fairing, where it evaporated into highly flammable vapors.
Findings
- The primary cause of the fire was the introduction of a foreign object between the brake disc and the brake pad, which generated a spark during braking.
- This spark ignited the accumulated fuel vapors trapped under the wheel fairing.
- The fuel supply was facilitated by the tanks being filled to capacity, allowing fuel to escape via the vent.
- High ambient and solar temperatures contributed to the rapid evaporation of the fuel into a combustible vapor state.
- The pilot's initial perception of brake malfunction was likely caused by the same foreign object interfering with the braking mechanism.