What was found
FLIGHT 3928, THE CREW REPORTED THAT PRIOR TO LEVELING OFF AT 10,000 FT AFTER DEPARTURE, RECEIVED A PITCH TRIM MAIN INOPERATIVE WARNING MESSAGE ON EICAS. AIRCRAFT DIFFICULT TO CONTROL. CAPTAIN REQUESTED PTRIM MAIN INOPERATIVE CHECKLIST IN AOM VOL 1. AOM PROCEDURES WERE COMPLIED WITH AND AN EMERGENCY WAS DECLARED. AIRCRAFT RETURNED AND LANDED WITHOUT INCIDENT. VISUALLY INSPECTED EXTERIOR FOR ANY ABNORMALITIES OR DAMAGE, NONE REPORTED. AIRCRAFT REMOVED FROM SERVICE. PERFORMED FIRST OFFICER’S YOKE PITCH TRIM SERVICING IAW AMM 27-40-03. OPS CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.