C8/2002L Hot-air balloon accident in Hämeenlinna on 7 September 2002
On Saturday 7 September 2002 at 07.35 there was a hot-air balloon accident in Hämeenlinna, when a hot-air balloon OH-APU, Cameron N-65, descended through a 110 kV electric line after the burner had died. The Accident Investigation Board Finland decided on 9 September 2002 to initiate an investigation C 8/2002 L into the accident. Investigator Olli Luoma was appointed as the chairman and investigator Ville Hämäläinen as the member of the investigation commission.
The balloonist was on a private flight and had flown at 1200 ft above ground level for about 10 minutes. When he descended to 300-500 ft in an attempt to find a landing spot, the pilot flames of both of his burners died. The balloonist tried to re-light the flames using the piezo igniters of the burners as well as his own igniter. The flames did not re-light and the balloon started descending and eventually the balloon collided with the electric line. The hot-air balloon was substantially damaged in the electric shock that followed. The balloonist was not injured.
The investigators determined that the pilot flames were significantly smaller than normal. The left vaporiser piston that controls the pilot flame size was completely stuck. The right piston was very stiff. The investigators determined that the cause of the accident was too small pilot flames. Contributing factors were irregular greasing of the vaporiser pistons and the fact that the burner maintenance instructions do not define detailed subjects.
The investigators recommended that the Finnish Aeronautical Association would inform the users of the hot-air balloons registered in Finland of the deficiencies in the hot-air balloon maintenance instructions. The Flight Safety Authority did not comment the recommendation. The Finnish Aeronautical Association had already informed the users.