What was found
(CAN) ON DESCENT, FLIGHT CREW NOTICED A STRONG BURNING PLASTIC ODOR IN THE COCKPIT. AN EMERGENCY WAS DECLARED AND FLIGHT CREW DONNED THEIR OXYGEN MASK. SOME ELECTRICAL SYS AND ENGINE BLEEDS WERE TURNED OFF. AFTER FEW MINUTES THE ODOR DISSIPATED. ACFT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE TEAM, DISPATCHED TO THE OUTSTATION, DETERMINED THAT THE CONTAMINATION SOURCE ORIGINATED FROM THE NR 1 BLEED SYS. THE ACFT WAS FERRIED TO A MAINTENANCE BASE WITH THE NR1 BLEED SYS SELECTED OFF. FURTHER TROUBLESHOOTING REVEALED PRESENCE OF GLYCOL CONTAMINATION TRACES AT THE INTER COMPRESSOR CASE, ICC, PLENUM, A PARTICLE WAS ALSO FOUND AT THE ICC DRAIN. THE DRAIN WAS CLEANED, ENGINE RAN, ENVIRONMENTAL SYS TESTED AND TEST FLIGHT SUCCESSFULLY CONDUCTED BEFORE RETURNING THE ACFT INTO SERVICE.