C172 flight instructor and student reported a failure of the electrical system during a training flight resulted in heading deviations and lost communications. The flight continued in visual conditions to landing.
Synopsis
C172 flight instructor and student reported a failure of the electrical system during a training flight resulted in heading deviations and lost communications. The flight continued in visual conditions to landing.
Narrative
While operating under IFR flight rules and mixed VMC/IMC conditions during an instrument training flight and receiving radar vectors for the ILS the electrical system failed completely. The flight was continued in VMC conditions and landed without further incident at the airport of origin. On the downwind of the ILS the aircraft and crew encountered an area of moderate turbulence in IMC conditions while the student (PF) was flying the aircraft and the instructor (PM) was monitoring. The student was struggling to maintain altitude and heading (+/- 20 degrees; 150 feet) so the instructor (PM) told the student (PF) to fly the attitude indicator and keep the wings level. Once clear of the turbulence the student returned to the assigned heading and altitude. The controller then stated that the aircraft had been flying off course by approximately 20 degrees to the right and the instructor advised the controller of the encountered turbulence as the reason for the deviation. The controller issued a turn inbound to intercept the ILS However; because the student (PF) was not yet prepared for the approach; delay vectors were requested and a turn to 360 was issued. The controls were transferred to allow the student to focus on preparing for the approach without the added workload of flying once the aircraft was on the assigned delay vector heading.While receiving delay vectors for the ILS the student (PM) was preparing for the instrument approach. ATC asked that we once again check our heading as they were showing the aircraft flying approximately 15-20 degrees right of the assigned heading. It was verified that we were on the appropriate heading on the HSI of 360 and checked the magnetic compass which indicated 020. The instructor (PF) noticed a message had come up on the Garmin G5 that we were using as the primary instrument source which read 'Not receiving ARINC data'. The instructor (PF) grabbed the STC for the G5 and handed it to the student (PM) asking that they find information on this message and to run the appropriate checklist.The instructor (PF) attempted to report the equipment issue to ATC on the communication 1 radio and the Garmin 430 GPS/COMM1/NAV1 subsequently failed. Realizing this may be an electrical system failure and in present VMC conditions the instructor decided to stay in those conditions and vacate the assigned heading and altitude while the failures were being addressed. The instructor (PF) began a descending turn to return to the airport and to stay below the layer of clouds. The instructor (PF) attempted to contact ATC on the communication 2 radio and was not able to contact them however was still able to hear the instructions and altitude alerts for deviating altitude and heading assignments. The instructor (PF) squawked 7600 and continued to contact ATC once more to no avail. The communication 2 radio and the transponder failed soon after. This occurred within a time frame of approximately 2 minutes.To begin troubleshooting the instructor (PF) looked at the ammeter and it was showing an indication of 0; the high voltage light was not illuminated; and there were no circuit breaker faults. Because this was an un-annunciated electrical failure the student (PM) was instructed to turn off the master switches; as all of the electrical components had failed; in accordance with the checklist.The flight was continued under VFR in VMC conditions. The student (PM) was able to use their handheld radio to make contact with the ATC tower and advised of what had happened. The tower issued a landing clearance and the aircraft landed safely without further incident by the instructor (PF).Maintenance personnel were able to determine that the battery had suffered a catastrophic failure.
Second reporter narrative
[Report narrative contained no additional information.]
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.