Narrative:

I was acting a pilot-in-command of a M20C single-engine aircraft that was conducting late afternoon familiarization and maintenance test flight when I suffered a loss two way communications while in class C airspace. I and another pilot were flying the aircraft when we began to experience an abnormally high amp reading on the amp meter and a weak and intermittent transponder and temporary loss of communication radio when nearing the class C airspace. While the altitude inoperative annunciator was not illuminated; I soon discovered the alternator was not functioning properly and it was spiking the electrical system with excess voltage. The decision was made to land at our final destination and seek repair. The landing occurred without incident and under two way radio communication provided by the aircraft battery power. The aircraft was then repaired and was returned to service. Two days later myself and a fellow pilot decided to test fly the aircraft; test the electrical system after the repair; and simultaneously conduct a mooney M20C familiarization flight for the other pilot. I maintained authority and responsibility as pilot-in-command for bother regulatory and insurance purposes for the flight in question. After waiting at the FBO for passing IMC and thunderstorms; I conducted the preflight inspection; started the engine; and requested a clearance to remain in closed traffic. After function checking the alternator and electrical system; which appeared to be functioning properly; we departed and made numerous touch and go landings while monitoring the electrical system and conducting the familiarization flight. During the course of these extensive explanations the electrical system failed again and the transponder and communication radio number one became intermittent and failed. Due to my distraction by the routine of more than 10 touch and goes; I failed to realize the failure and thus we became out of two way radio communication while in the closed traffic pattern. I didn't realize the electrical issue until after we had already done two circuits and I quickly pushed the alternator circuit breaker back in which allowed me to again make communication with the tower. I then requested a full stop and taxi to the ramp. In order to keep the radio operative; I was required to reset the circuit breaker approximately every 20 seconds until engine shutdown. I was not out of communication for more than 10 minutes and we maintained a constant vigil for traffic in the pattern. In hind sight; a maintenance test flight should never be conducted along with a familiarization flight and I will never make that mistake again; as too much can go wrong and full attention should be paid to the primary task. Further immediately upon landing I conducted a de-briefing with the other non-flying pilot to understand and learn from what happened. In conclusion; I deeply regret my errors and any issues or inconvenience that occurred because of it and I wish to do whatever it takes to make it right and correct the indiscretion.

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Original NASA ASRS Text

Title: An M20C pilot suffered electrical and communications failures on two flights despite maintenance performed following the initial event.

Narrative: I was acting a pilot-in-command of a M20C single-engine aircraft that was conducting late afternoon familiarization and maintenance test flight when I suffered a loss two way communications while in Class C airspace. I and another pilot were flying the aircraft when we began to experience an abnormally high AMP reading on the AMP meter and a weak and intermittent transponder and temporary loss of communication radio when nearing the Class C airspace. While the ALT INOP annunciator was not illuminated; I soon discovered the alternator was not functioning properly and it was spiking the electrical system with excess voltage. The decision was made to land at our final destination and seek repair. The landing occurred without incident and under two way radio communication provided by the aircraft battery power. The aircraft was then repaired and was returned to service. Two days later myself and a fellow pilot decided to test fly the aircraft; test the electrical system after the repair; and simultaneously conduct a Mooney M20C familiarization flight for the other pilot. I maintained authority and responsibility as pilot-in-command for bother regulatory and insurance purposes for the flight in question. After waiting at the FBO for passing IMC and thunderstorms; I conducted the preflight inspection; started the engine; and requested a clearance to remain in closed traffic. After function checking the alternator and electrical system; which appeared to be functioning properly; we departed and made numerous touch and go landings while monitoring the electrical system and conducting the familiarization flight. During the course of these extensive explanations the electrical system failed again and the transponder and communication radio number one became intermittent and failed. Due to my distraction by the routine of more than 10 touch and goes; I failed to realize the failure and thus we became out of two way radio communication while in the closed traffic pattern. I didn't realize the electrical issue until after we had already done two circuits and I quickly pushed the alternator circuit breaker back in which allowed me to again make communication with the Tower. I then requested a full stop and taxi to the ramp. In order to keep the radio operative; I was required to reset the circuit breaker approximately every 20 seconds until engine shutdown. I was not out of communication for more than 10 minutes and we maintained a constant vigil for traffic in the pattern. In hind sight; a maintenance test flight should never be conducted along with a familiarization flight and I will never make that mistake again; as too much can go wrong and full attention should be paid to the primary task. Further immediately upon landing I conducted a de-briefing with the other non-flying pilot to understand and learn from what happened. In conclusion; I deeply regret my errors and any issues or inconvenience that occurred because of it and I wish to do whatever it takes to make it right and correct the indiscretion.

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.