Flight to YVS

Today was a brilliant day to go flying. A high pressure system was in the area, bringing moderate temperatures, some scattered clouds around 5,000 feet, and light/variable winds out of the north. I offered my brother-in-law to take him up for his flight, to which he duly agreed.

Upon landing at our cross-country destination, I noticed the “LOW BUS VOLT” annunciator panel light begin to flicker – while we were still in flight. I found this odd.

According to the Archer III POH, the electrical system on board the PA3 is a 28-volt system, with a 24-volt battery for usage during the start-up procedure and to backup the alternator output. I was never aware of the fact that the battery is located in the aft fuselage on a battery shelf, I was always under the impression it was under the hood somewhere! More information concerning what exactly drives the LOW BUS VOLT light is unfortunately, not available in the POH. We do however, know that during night flight, the average continuous load on the digital ammeter should read about 32 amperes.

In the end, it is believed that the faulty light comes on because a short in the sensor, which costs a whopping $2300.00 to replace. My club will attempt to troubleshoot the issue before purchasing the spare part. As a safety precaution, I have cancelled my flight for Monday evening because I wouldn’t feel easy with that light flickering on when I’ve got passengers flying around at night. Better safe than sorry.