What was found
EXTERNAL POWER ANNUNCIATOR WOULD NOT EXTINGUISH. FOUND AFT STIFFENER IN LEFT NACELLE AFT SKIN HAD CHAFED THROUGH INSULATION ON ELECTRICAL LEADS THAT GO FROM THE EXTERNAL POWER RECEPTICAL IN THE WHEEL WELL, TO THE EXTERNAL POWER RELAY IN THE LEFT NACELLE. THIS CAUSED THESE LARGE (6 OR 8 GAUGE) WIRES TO BE GROUNDED TO THE AIRFRAME SUGGEST REROUTING OR BETTER ANTI CHAFE PROTECTION POTENTIAL FOR FIRE OR SEVERE. ELECTRICAL PROBLEMS.