Narrative:

I was cleared for takeoff; runway xx; and to turn on course southwest (heading 222). I lined up with the runway and verified that the dg aligned with runway heading then applied full power. I called 'airspeed alive and gauges in the green;' and right about 85 mph I had an electrical failure and I determined that it was unsafe to stop the aircraft at that point and took off the ground. I made a left turn at about 1;000 feet AGL from the runway to join a base and I made another left turn to join a downwind. By then I had determined that the avionics master switch had failed; as it was a toggle switch that felt 'empty' and it wasn't making any click as it normally did. When I was abeam the departure end of runway 33 on the left downwind I dropped the landing gear to signal to the tower that I needed to comeback in. I added 20 degrees of flaps to slow down (105 mph) and waited for tower to acknowledge the situation. I waited for light signals from tower; I flew approximately 2 nm in the left downwind that was about 1 nm wide and then I did 2 (on the angle formed by the downwind and base) 360s waiting for light signals. I didn't see light signals; maybe because the tower glass was tinted darker. I proceeded with caution to join the left base and then with caution to join final for runway xx; all while looking for any light signal. I landed the aircraft and cleared the runway at the end. I then looked to the tower and within a few moments I seen the green signal to taxi. I taxied via B to cross runway xx and waited for another signal to cross. I parked the plane at an avionics shop ramp and called tower. They said it was no problem; that they realized what had happened; and asked if I had seen the signals when I was in the air. I told them I hadn't seen the signals but proceeded with great caution. The winds on ATIS at takeoff were 290 at 15-23 approximately. Due to the higher winds there was no traffic at the field on this day.

Related reports:

Google
 

Original NASA ASRS Text

Title: PA34 pilot had electrical failure on takeoff; resulting in return to airport.

Narrative: I was cleared for takeoff; Runway XX; and to turn on course southwest (Heading 222). I lined up with the runway and verified that the DG aligned with Runway Heading then applied full power. I called 'Airspeed alive and gauges in the green;' and right about 85 MPH I had an electrical failure and I determined that it was unsafe to stop the aircraft at that point and took off the ground. I made a left turn at about 1;000 feet AGL from the runway to join a base and I made another left turn to join a downwind. By then I had determined that the avionics master switch had failed; as it was a toggle switch that felt 'empty' and it wasn't making any click as it normally did. When I was abeam the departure end of Runway 33 on the left downwind I dropped the landing gear to signal to the Tower that I needed to comeback in. I added 20 degrees of flaps to slow down (105 MPH) and waited for Tower to acknowledge the situation. I waited for light signals from Tower; I flew approximately 2 nm in the left downwind that was about 1 nm wide and then I did 2 (on the angle formed by the downwind and base) 360s waiting for light signals. I didn't see light signals; maybe because the Tower glass was tinted darker. I proceeded with caution to join the left base and then with caution to join final for Runway XX; all while looking for any light signal. I landed the aircraft and cleared the Runway at the end. I then looked to the Tower and within a few moments I seen the green signal to taxi. I taxied via B to cross Runway XX and waited for another signal to cross. I parked the plane at an avionics shop ramp and called Tower. They said it was no problem; that they realized what had happened; and asked if I had seen the signals when I was in the air. I told them I hadn't seen the signals but proceeded with great caution. The winds on ATIS at Takeoff were 290 at 15-23 approximately. Due to the higher winds there was no traffic at the field on this day.

Data retrieved from NASA's ASRS site 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.