The aircraft’s right main landing gear failed as it landed on Runway 26 at Isle of Man Airport. The right main landing gear detached, the aircraft slid along the runway on its remaining landing gears, right wingtip and luggage pannier and came to rest on the grass adjacent to the runway. The passengers and crew vacated the aircraft without injury. The mechanism to final failure is not yet fully understood, but was initiated as a result of stress corrosion cracking in the forward yoke pintle at the top of the right main landing gear leg. One Safety Recommendation is made.