On January 28, 2014, about 1515 Pacific standard time, a Piper PA-23, N5977Y, sustained substantial damage following the collapse of the right main landing gear during the landing roll out at the Camarillo Airport (CMA), Camarillo, California. The airplane was registered to Red State, LLC and was operated by the pilot under the provisions of 14 Code of Federal Regulations, Part 91 as a personal flight. The commercial pilot and the pilot rated passenger were not injured. The flight originated from Bob Hope Airport (BUR), Burbank, CA, at 1440 with a planned destination of CMA. Visual meteorological conditions prevailed for the flight and no flight plan was filed. The pilot reported in a written statement to the National Transportation Safety Board (NTSB), investigator-in-charge (IIC), that the purpose of the flight was landing operations and airplane familiarization at CMA for the commercial pilot. After completing a touch-and-go landing in the traffic pattern at CMA, the pilot performed prelanding procedures and landed a second time on runway 26. He stated that after touching down, the right wing contacted the ground and the airplane came to a stop on the runway. The right aileron was substantially damaged. A postaccident examination of the airplane was conducted by a local mechanic. The examination revealed that the right main landing gear was down and the downlock was not in the locked position during landing. No mechanical anomalies were noted with the landing gear system. The hydraulic power-pack was sent to a repair shop for further examination. According to the repair shop, the hydraulic power-pack was bench tested which revealed that it was bypassing the detent internally. During the teardown of the unit, a damaged o-ring was found on the gear selector shaft. This damaged o-ring was not allowing the fluid to build pressure and hold. The repair shop further reported that the unit's oil and internal surface was very dirty.