DA40 Flight Instructor and student reported alternator failure and diversion to nearby airport.
Synopsis
DA40 Flight Instructor and student reported alternator failure and diversion to nearby airport.
Narrative
IP (Instructor Pilot) and SP (Student Pilot) were performing right seat transition practice of CAX (Commercial Pilot Airplane) maneuvers at 4500 ft. SP just finished a maneuver when 'Volts Low' annunciation came on. IP took controls and told SP to pull out the QRH and flip to 'Volts Low (Possible Alternator Failure) 3-3'. As SP was grabbing the handbook IP immediately began initiating a climb and turn towards the nearest airport. While initiating the climb and proceeding direct to ZZZ the 'Alternator Fail' annunciation illuminated. IP checked the engine page and Volts were yellow with the Amps dropped down to zero. IP looked over at the QRH with the student and then both 'Volts Low' and 'Alternator Fail' annunciations disappeared. Volts returned to green and amps were fluctuating. IP and SP considered it could have been a sensor issue and contemplated the best course of action. While talking and continuing the climb; the 'Volts Low' annunciation came back followed by 'Alternator Fail' with the volts and amps rapidly dropping. IP decided that there was most likely an issue and told the SP we will follow the QRH and shed load. The Essential Bus was activated and all unnecessary equipment was turned off. After turning on the essential bus; coms between IP and SP were disconnected and communication was difficult between the noise of the engine and nearby radio communications on the CTAF. SP held up the checklist and communication was made by hand gestures. When over ZZZ runway XX IP told the SP we would just steep spiral down to the runway and perform a normal landing. IP made radio calls during the maneuver until clear of the runway and at the ramp. Maintenance was notified and sent a technician out to fix the issue. A broken terminal was found in the cowling and was replaced.
Second reporter narrative
At about 3000 feet were stating to get Volts low annunciation followed by an inconsistent alternator fail annunciation . At that time we immediately pulled out the QRH and started a climb to gain altitude in case of engine failure. Once MCT (Maximum Continuous Thrust) was introduced the annunciations extinguished for about 30 sec then ignited again. We executed a steep spiral over runway XX numbers into an emergency landing. The engine stayed on for the entire event.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.