As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 4100 - CREW REPORTED THAT WHEN THE GROUND POWER UNIT WAS CONNECTED TO THE AIRCRAFT THAT SPARKS SHOT OUT FROM AROUND THE PLUG AND THE COCKPIT FILLED UP WITH SMOKE. SMOKE CLEARED AFTER GPU WAS DISCONNECTED. MAINTENANCE FOUND THE BACK SIDE OF THE GROUND POWER BOX DAMAGED. MAINTNANCE REPAIRED THE GROUND POWER BOX USING SRM 53-11-28. OPERATIONAL CHECKS WERE GOOD. AIRCRAFT RETURNED TO SERVICE. (M)