Super King Air 300
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Engineer; Flight Crew Flight Instructor
Flight Crew Last 90 Days 40; Flight Crew Total 10200; Flight Crew Type 800
Aircraft Equipment Problem Critical; Ground Event / Encounter Other / Unknown
Aircraft Aircraft Damaged; Flight Crew Landed in Emergency Condition; General Maintenance Action
Aircraft
Training flight for approaches with two successful gear extension and retraction sequence's with no incident. On the third visual pattern the right gear down and locked light was not illuminated. We retracted the gear with no problems; attempted to lower the gear again the same right gear light would not illuminate with gear selected down. Retracted the gear and ran the abnormal gear extension checklist then returned to ZZZ. After clearance for the approach; the gear was lowered with the right gear light not illuminated. Landing gear circuit breaker checked and gear down lights push to test checked; again all normal. Asked the tower to confirm what we saw from the cockpit the gear down in the normal position and tower confirmed that both gear appeared to be down. Briefed on a soft touchdown and to exit the runway and shutdown and wait for tow. Also; briefed if the gear collapsed the plan was perform the emergency engine shut down on the ground and egress out of the main cabin door.  The gear collapsed after the rollout and the start of taxi off the runway. Performed as briefed the emergency engine shut down and evacuation.
BE300 Captain reported an unsafe right gear indication after two successful touch and goes. During a flyby the Tower indicated that the gear appeared to be down. While taxiing off the runway the right gear collapsed.