PA-30 Twin Comanche
Flight Crew Flight Instructor; Flight Crew Commercial
Flight Crew Last 90 Days 44; Flight Crew Total 12865; Flight Crew Type 150
Distraction; Situational Awareness
Aircraft Equipment Problem Critical; Ground Event / Encounter Ground Strike - Aircraft
Aircraft Aircraft Damaged; Flight Crew Landed in Emergency Condition
Aircraft
I was giving multiengine dual instruction in reference airplane. We departed and flew to the training area. We did steep turns and slow flight with gear and flaps down. We noticed a squeal noise in the headsets. When we tried to contact Approach we lost radio contact. At that time we decided to return to [departure airport]; and again we were unable to contact the Tower. We set the transponder to 7600; and called the Tower using my cell phone and relay we had no radios.Then; when we tried to lower the landing gear we didn't get a green light and the nose gear looked that it was partially down. We turned off all electrical equipment; leaving the battery on and tried to recycle the gear; but the nose gear remained partially down.I called the Tower again on my cell phone and relayed my situation; and told the controller we were going to extend the gear manually. We refer to the checklist and follow the instructions printed on the reverse side of the landing gear operating motor access cover. After several attempts at lowering the gear manually; we made a low pass for the Tower to check our gear; but they couldn't tell because it was already night time.At that time we decided to land; even though we did not know the status of the gear. Upon touchdown; the airplane skidded on its belly and came to stop near the center of the runway. We deplaned without any further difficulty without sustaining any injuries to ourselves or doing any damage to other property.In retrospect; I could had been paying closer attention to any indication of loss of the electrical system. If there were any; I could have turn off all the electrical systems and save battery power for extending the gear. I've had electrical failures before so probably I missed them this time. Also I could have been more familiar with the emergency landing gear extension system. I think I followed the instructions printed on the cover of the access panel to the emergency extension handle. But I get the feeling that I could have done more to get the gear down and locked.
PA-30 Twin Comanche flight instructor reported an electrical failure that led to a landing gear extension problem and gear collapse on landing.