What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO GND DUE TO THE FLIGHT CREW REPORTING THAT AFTER TAKEOFF CLIMBING THROUGH 400' THERE WAS A VERY STRONG FUME EVENT IN FLIGHT DECK AND CABIN AFFECTING EYES, NOSE, THROAT AND CHEST. NO VISIBLE SMOKE OR FUMES. THE AIRCRAFT LANDED SAFELY AT GND WITHOUT FURTHER INCIDENT. THE FLIGHT CREW REPORTED THAT THERE WAS NO VISIBLE OIL STREAKING ON OUTSIDE OF AIRCRAFT NOTED DUIRNG THE POST FLIGHT WALKAROUND. MAINTENANCE ACCOMPLISHED SMOKE / ODOR / FUME TROUBLESHOOTING PER JOB CARD 26L00021001 AND A DECONTAMINATION OF THE ENVIRONMENTAL CONTROL SYSTEM PER JOB CARD 26L00021013 WITH NO ODORS NOTED.