As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE MAINTENANCE, CHANGING RIGHT COWL FLAP CABLE, THE HEATER'S FUEL LINE CONTACTED THE NON-INSULATED TERMINAL BOARD'S STUD AT RIGHT WING STA 27.125. PLACING MASTER SWITCH IN ON POSITION PROVIDED A SHORT CIRCUIT AND FIRE. THE TERMINAL BOARD'S STUDS NEED TO BE INSULATED FROM FUEL AND OIL LINES IN IMMEDIATE AREA.