What was found
THE A-SYSTEM HYDRAULIC OVERHEAT LIGHT ILLUMINATED AFTER TAKEOFF WHILE CLIMBING THROUGH 6000 FEET. A MINUTE LATER, THE A-HYDRAULIC SYSTEM QUANTITY WENT TO ZERO. THE HYDRAULIC FAILURE CHECKLIST WAS PERFORMED, FUEL WAS DUMPED, AND THE AIRCRAFT WAS RETURNED TO IAH WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND AILERON CONTROL MODULE LEAKING. THE AILERON CONTROL MODULE WAS REPLACED. THE HYDRAULIC SYSTEM WAS SERVICED. LEAK AND OPERATIONAL CHECKS WERE GOOD.