What was found
AFTER APPROX 5 MINUTES OF FLIGHT AFTER TAKE OFF FROM EC-160, PILOT NOTICED A STRONG ODOR OF FUEL AND GAUGE WAS FUNCTIONING PROPERLY. RETURNED TO EC-106, SHUT DOWNED AND INSPECTION OF AIRCRAFT SHOWED MISING FUEL CAP. FUEL CAP HAD BEEN REPLACED AFTER REFUELING AND WAS PRESENT ON PREFLIGHT WALK AROUND. MAINTENANCE INSTALLED NEW FUEL CAP AND AIRCRAFT WAS INSPECTED FOR DAMAGE, NONE FOUND, RETURNED AIRCRAFT TO SERVICE.