While performing practice instrument approaches, the certified flight instructor (CFI) and pilot under instruction noticed that the right main landing gear indicator light was not illuminated when the landing gear handle was down. A visual check by the CFI confirmed that the right main landing gear was not down and locked. The crew cycled the landing gear and attempted to pump the gear down using the emergency gear handle. Both procedures were unsuccessful in bringing the right main landing gear into a down and locked position. The flight crew landed the airplane on the runway with the left main down and the right main partially extended. The right horizontal stabilizer impacted the runway causing the airplane to veer right, off the runway, and substantially damaging the horizontal stabilizer. A post flight inspection by a airframe and powerplants mechanic determined that the landing gear actuator splined drive shaft had failed. Cessna Service Bulletin SEB11-02, issued in April 2011, recommended a one time inspection of the main landing gear steel pivot assembly. According to the mechanic, the airplane maintenance records do no show that the recommended inspection had been performed.