What happened
During a private flight over Gotland, a pilot and a passenger landed at Gotland's airport. After touching down on runway 03, the pilot continued the rollout and received clearance from the tower to turn around on the runway. The aircraft proceeded to taxi via the taxiway system toward the Gotland Flying Club.
As the aircraft approached its parking position, the occupants noticed a faint odor of smoke. Upon reaching the parking spot, visible smoke and flames emerged from the area in front of the wing. The pilot immediately directed the passenger to evacuate the aircraft. While the pilot attempted to suppress the fire at the left landing gear using a portable extinguisher, the local municipal fire and rescue service arrived to fully extinguish the flames.
The investigation
Investigators examined the aircraft for technical malfunctions but found no mechanical faults that would inherently cause a fire. However, investigators noted an oil stain on the hangar floor at the exact location where the brake caliper had been positioned during parking.
Further scrutiny of the maintenance records revealed that the installed brake hose was not included in the aircraft's current maintenance program. Consequently, the hose had likely exceeded its recommended service life by a significant margin. Reference taxiing conducted during the investigation demonstrated that even with light braking, the brake disc could reach temperatures sufficient to ignite hydraulic oil.
Findings
- The fire was caused by atomized hydraulic oil spraying onto a heated brake disc, which subsequently ignited.
- The fire spread from the brake area to the tires, wheel covers, and other flammable components near the landing gear.
- A failure in the airworthiness organization's routines meant that the brake hose's calendar life was not being monitored.
- The maintenance program failed to incorporate all necessary tasks prescribed by the type certificate holder, specifically regarding the inspection and replacement intervals for the brake hose.