Incomplete compliance with a non-mandatory Cessna Service Information Letter by an unknown person resulting in pulling through of the attach bolt of the upper and lower link assemblies and subsequent rotation of the right wheel assembly. Additionally, improper overhaul of the right main landing gear actuator by an unknown person resulting in collapse of the right main landing gear. Findings in the investigation were: 1) Inadequate compliance with a Cessna Service Bulletin (SB) by company maintenance personnel for failure to replace the actuator as addressed in the SB due to a discrepancy with the actuator noted during the post incident testing, and 2) Failure of the FAA to include inspection of the main landing gear torque links in the FAA approved inspection program as described in the Cessna Progressive Care Program.