Narrative:

I started an engine break-in flight late in the afternoon. About 45 minutes into the flight; I noticed the alternator inoperative and low bus voltage annunciators illuminated. I cycled the alternator switch in accordance with the emergency procedure; and both annunciators were extinguished. About 15 minutes later; the alternator inoperative annunciator turned back on. Over the course of the next 15 minutes; the alternator failed and I resolved it in this manner about 6 times. I decided this electrical problem could be managed and that I didn't need to interrupt the 2.5-hour break-in flight. I informed the TRACON; from whom I was receiving traffic advisories; that I wished to cancel radar service. I also informed them that I would be turning off my transponder and would be a primary target only for about another hour. I then turned off the battery and alternator switches for most of the duration of the flight. I turned the battery on periodically to monitor the engine and fuel; but all electrical remained off most of the remainder of the flight. After I completed the break-in; I turned the battery on along with the transponder and strobes; and returned to the class C airport. Shortly after entering class C airspace; the low bus voltage annunciator illuminated once again. I asked tower if I could turn the transponder off to shed electrical load. Upon receiving permission I did so; and turned the alternator back on to bump up the battery voltage one last time. I then landed without further incident. Obviously; I violated 91.7 when I failed to discontinue the flight when an unairworthy condition occurred. I also violated 91.209 by turning the strobes off for a reason other than operational safety. My rationale was that interrupting the engine break-in would damage the engine; so I wanted to continue the flight if possible. In my analysis before deciding to continue with all electrical off; I considered declaring an emergency so I could operate without strobes. But I decided that declaring an emergency would require me to return to the airport after doing so; so I decided not to declare. I considered that I didn't really know what was happening in the electrical system to give the indications I observed. But I decided on a VFR day the risk was low for continuing the flight. In hindsight; the best course of action would have been to discontinue the break-in and return to the home airport after the second alternator failure.

Google
 

Original NASA ASRS Text

Title: PA28-181 pilot reported an electrical failure resulting in airspace and airworthiness FAR violations by continuing the maintenance flight.

Narrative: I started an engine break-in flight late in the afternoon. About 45 minutes into the flight; I noticed the ALTERNATOR INOP and LOW BUS VOLTAGE annunciators illuminated. I cycled the alternator switch in accordance with the emergency procedure; and both annunciators were extinguished. About 15 minutes later; the ALTERNATOR INOP annunciator turned back on. Over the course of the next 15 minutes; the alternator failed and I resolved it in this manner about 6 times. I decided this electrical problem could be managed and that I didn't need to interrupt the 2.5-hour break-in flight. I informed the TRACON; from whom I was receiving traffic advisories; that I wished to cancel radar service. I also informed them that I would be turning off my transponder and would be a primary target only for about another hour. I then turned off the battery and alternator switches for most of the duration of the flight. I turned the battery on periodically to monitor the engine and fuel; but all electrical remained off most of the remainder of the flight. After I completed the break-in; I turned the battery on along with the transponder and strobes; and returned to the class C airport. Shortly after entering class C airspace; the LOW BUS VOLTAGE annunciator illuminated once again. I asked tower if I could turn the transponder off to shed electrical load. Upon receiving permission I did so; and turned the alternator back on to bump up the battery voltage one last time. I then landed without further incident. Obviously; I violated 91.7 when I failed to discontinue the flight when an unairworthy condition occurred. I also violated 91.209 by turning the strobes off for a reason other than operational safety. My rationale was that interrupting the engine break-in would damage the engine; so I wanted to continue the flight if possible. In my analysis before deciding to continue with all electrical off; I considered declaring an emergency so I could operate without strobes. But I decided that declaring an emergency would require me to return to the airport after doing so; so I decided not to declare. I considered that I didn't really know what was happening in the electrical system to give the indications I observed. But I decided on a VFR day the risk was low for continuing the flight. In hindsight; the best course of action would have been to discontinue the break-in and return to the home airport after the second alternator failure.

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.