As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE COMING OUT OF LEFT DISTRIBUTION BOX. CAPTAIN SAID ONLY A COUPLE OF CLEANERS WERE ONBOARD DURING PREFLIGHT THE CAPTAIN SAID THEY SMELLED AN ELECTRICAL BURING SMELL THAT CAME FROM LEFT DISTRIBUTION BOX. FOUND K0291 BURNT, REMOVED AND REPLACED APU LINE CONTACTOR IAW AMM 24-34-03.