What was found
CLT - FLT 1458 - AFTER TAKEOFF, 'GND/FLT CONTROL' MESSAGE ALONG WITH MASTER CAUTION LIGHT WOULD INTERMITTENTLY APPEAR EVERY 2-3 MINUTES. FLIGHT RETURNED TO CLT AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED THE PROXIMITY SWITCHING ELECTRONIC UNIT, NR 3 AND NR 4 GND/FLT SENSOR, AND RIGHT MAIN GEAR GND/FLT HARNESS. REF: OPERATOR CONTROL NR USAAF98053, AND, 98ZZZX2829 THROUGH 98ZZZX2831.