What was found
DURING RE-INSTALLATION OF OXYGEN BOTTLE AFTER HYDROSTATIC TEST, MECHANIC NOTED SOUND LIKE OXYGEN LEAK. DURING ATTEMPT TO TIGHTEN FITTING, NOTED GREEN GLOW AT REGULATOR, WITH SPARKS. MECHANIC CLEARED AREA AND 2 EXPLOSIONS NOTED. FIRE BURNED HOLES IN AIRCRAFT NOSE SKIN BELOW OXYGEN REGULATOR, FIRE EXTINGUISHER USED, FIRE PUT OUT. INSPECTION FOUND REGULATOR BURNED THROUGH ABOUT MID-WAY.