As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
VERY STRONG ACID ELECTRICAL SMELL LIKE BURNING PLASTIC IN THE DESCENT STARTING AT FL180. PERFORMED GVI IN BOTH PACK BAYS WITH NO OBVIOUS FAULTS NOTED. DURING RIGHT ENGINE RUN, EXHAUST FUMES WERE DETECTED IN THE FLIGHT DECK. SWAPPING BETWEEN PACK 1 AND PACK 2 HAD NO EFFECT. FURTHER TROUBLESHOOTING NEEDED.