A FRICTION CAUSED IGNITION OCCURRED ON THE FACE OF LONGWALL PANEL 49 NEAR 143 SHIELD. THE OPERATOR STATED HE OBSERVED A BLUE AND ORANGE FLAME ABOUT 1.5 CUBIC FEET WRAP AROUND THE HEAD DRUM OF THE SHEARER FOLLOWING THE BITS INTO THE PANLINE. THE FLAME WAS REPORTED AS LASTING TWO TO THREE SECONDS AND WAS EXTINGUISHED BY THE DRUM SPRAYS AND SPRAY BAR.