Flight Crew Flight Instructor; Flight Crew Commercial; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 175; Flight Crew Total 1260; Flight Crew Type 1260
Aircraft Equipment Problem Critical; Ground Event / Encounter Gear Up Landing
Aircraft Aircraft Damaged; Flight Crew Executed Go Around / Missed Approach
Aircraft
I conducted a training flight with a student. A through preflight was conducted and the landing gear was visually inspected with no issues. Upon coming back in to ZZZ I extended the gear and had a green light and mains were down. Upon the student's landing; I felt the right main gear collapse under us. I immediate took the controls and executed a go-around. I exited the traffic pattern and exited the area to the west to troubleshoot. I cycled the gear up and down a few times and it still would not fully extend. I used the emergency gear extension checklist and the left main would not fully extend. I repeated this process multiple times. I made a phone call to our Maintenance Assistant Chief. He called [an] A&P and AI Mechanic. [The mechanic] called me on the phone and had me attempt to recycle the gear using the emergency gear extension. That did not work. I then exited the pattern and used maneuvers to see if I could get the gear to lock into place. That did not work. I retracted the gear and conducted a low pass to ensure the gear was retracted. The individuals on the ground said that the gear appeared to be retracted. I requested EMS to be present for the landing. I flew around to burn some fuel off and wait for the EMS to arrive. Once they arrived I conducted full flap no gear landing.
C172 pilot reported a gear-up landing was executed when all attempts to lower the landing gear failed.