What was found
CREW REPORTED A STRONG ODOR IN COCKPIT AND CABIN IN FLIGHT. EMERGENCY DECLARED AS A PRECAUTION. AIRCRAFT LANDED WITHOUT INCIDENT. MX RAN ENGINES WITH BLEEDS ON, NO DISCREPANCIES NOTED. NR 1 ENG WAS FOUND TO BE OVERSERVICED. OIL FROM NR 1 ENG DRAINED TO PROPER LEVEL. APU WAS SUSPECTED TO BE AT FAULT. MEL 49-1 ISSUED FOR APU. AIRCRAFT RETURNED TO SERVICE. DURING AIRCRAFT RUN ON 13 JANUARY 2003, MAINTENANCE OPERATED APU WITH NO PROBLEMS NOTED. AFTER FURTHER TROUBLESHOOTING IT WAS DISCOVERED RT ENGINE WAS CAUSE OF OIL IN BLEED SYSTEM DUE TO INTERNAL OIL COKING. ON 10 JANUARY 2003 RT ENG AIR SWITCHING VALVE REPLACED, NO ODOR FOUND ON ENGINE RUN. RT ENG REPLACED, AIRCRAFT RETURNED TO SERVICE.