Narrative:

I was five miles north of the airport on a training flight with a student. I was the instructor. I called the tower for clearance back in to land. Upon initial contact; my radios began to flicker and I was unable to contact tower. I tried for several minutes with no answer. I was also unable to talk to my student; and the radios kept switching to 121.5. Neither radio worked. I tried COM1 and COM2. Eventually the radios failed completely and I was unable to turn them on. The ELT then sounded and the alarm was going off loudly for the remainder of the flight. I squawked 7600 and had full VFR conditions so I climbed up to 4;000 MSL to get a visual of the airport to look for traffic and hoping to get a light gun signal. Upon reaching midfield; the remainder of the electrical system failed; the flaps would not work and I started to smell burning from the aircraft. With a full electrical failure and smoke and burning; I squawked 7700 and made an emergency landing without a landing clearance from tower. I was afraid we were on fire. I made sure there was no aircraft in the area and the landing was completed without incidence. After landing I exited the runway and received light gun clearance to taxi in so I taxied to the ramp. I immediately called tower and explained what had happened. I explained that I had an electrical failure and flight control failure. On final approach; the flaps had uncommanded oscillations up and down making the aircraft difficult to control. Tower said they were unable to pick up the transponder squawking 7600 or 7700.

Related reports:

Google
 

Original NASA ASRS Text

Title: The instructor pilot aboard a C172 landed without a clearance after suffering a total electrical system failure.

Narrative: I was five miles north of the airport on a training flight with a student. I was the instructor. I called the Tower for clearance back in to land. Upon initial contact; my radios began to flicker and I was unable to contact Tower. I tried for several minutes with no answer. I was also unable to talk to my student; and the radios kept switching to 121.5. Neither radio worked. I tried COM1 and COM2. Eventually the radios failed completely and I was unable to turn them on. The ELT then sounded and the alarm was going off loudly for the remainder of the flight. I squawked 7600 and had full VFR conditions so I climbed up to 4;000 MSL to get a visual of the airport to look for traffic and hoping to get a light gun signal. Upon reaching midfield; the remainder of the electrical system failed; the flaps would not work and I started to smell burning from the aircraft. With a full electrical failure and smoke and burning; I squawked 7700 and made an emergency landing without a landing clearance from Tower. I was afraid we were on fire. I made sure there was no aircraft in the area and the landing was completed without incidence. After landing I exited the runway and received light gun clearance to taxi in so I taxied to the ramp. I immediately called Tower and explained what had happened. I explained that I had an electrical failure and flight control failure. On final approach; the flaps had uncommanded oscillations up and down making the aircraft difficult to control. Tower said they were unable to pick up the transponder squawking 7600 or 7700.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.