On December 2, 2011, about 1425 Pacific standard time (PST), the right main landing gear of a Beech 76 Duchess, N23852, collapsed after landing at the San Carlos Airport, San Carlos, California. Bel-Air was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The commercial pilot with a certified flight instructor (CFI) certificate and the private pilot undergoing instruction (PUI) were not injured; the airplane sustained substantial damage to the right wing. The local instructional flight departed Livermore, California, about 1410. Visual meteorological conditions prevailed, and no flight plan had been filed. Shortly after takeoff, the pilot was notified by the tower controller that the right main landing gear did not appear to fully retract. The pilot then circled back around so that the controller could get a look at the gear. While on the downwind leg, the pilot cycled the gear to try and correct the discrepancy. During the low approach, the tower controller advised the pilot that all three landing gear appeared to be extended. The pilot then requested to depart to another airport. While on approach for landing, the pilot selected the gear down. The left and nose gear indication lights illuminated, however, the right did not. The pilot tested the light bulb and performed an emergency gear extension, which was unsuccessful. During a low approach, tower personnel reported that the landing gear appeared to be in the down position. The pilot was subsequently cleared to land, and during the landing roll everything appeared normal except for the right gear light was still not on. The pilot reported that he cautiously slowed the airplane to almost a complete stop before turning off the runway. During the turn, the right main landing gear collapsed. During the recovery, the airplane was lifted and the right main landing gear was extended and secured. An examination of the landing gear by the assigned Federal Aviation Administration inspector and maintenance personnel revealed that the A-frame assembly, PN-105-810023-68, failed in what appreared to be overload at the top/forward attach point.