As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHL - BOS - FLT 343 - AFTER TAKEOFF, AND THE LANDING GEAR WAS RETRACTED, THE RIGHT MAIN GEAR RED LIGHT STAYED ILLUMINATED. THE LANDING GEAR WAS CYCLED BUT THE RED LIGHT REMAINED ILLUMINATED. THE AIRCRAFT RETURNED TO THE FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED THE RIGHT MAIN GEAR UP LOCK PROX SENSOR. (M)