What was found
ON APPROACH AFTER SELECTING FLAPS 3 RECEIVED SLAT FAIL EICAS MESSAGE. EXECUTED GO AROUND. ONE LEVELED OFF, RAN QRH AND DECLARED EMERGENCY. LANDED WITH NO INCIDENT, SLATS AT 3 AND FLAPS AT 2. MAINTENANCE REMOVED AND REPLACED LHOB 3/4 SKEW SENSOR. SI 270826 TO REMOVE AND REPLACE LHOB 2/3 SKEW SENSOR WAS COMPLIED WITH ON 6/23/09.