As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, AIRSPEED UNRELIABLE / STUCK AT 270 KTS INDICATION OF OVERSPEED WITH FLAPS & GEAR UP AT 270 KTS. EMERGENCY DECLARED, AIR TURN BACK. (ATB) . MAINTENANCE T/S - ALT VMO SWITCH SELECTED IAW CDL 32-12-1. AIRSPEED TAPE WILL SHOW 270 KTS. PERFORMED LANDING GEAR OPERATION ABOVE DESIGN SPEED CONDITIONAL INSPECTION IAW B767 AMM 05-51-07. NO DEFECTS NOTED. A/C REMAINS NO ETOPS. A/C RETURNED TO SERVICE.