Yesterday I woke up to find sunny skies and mild winds. I checked the forecast to make sure it was not just a brief lull, and the airplane was available.
My lesson plan for myself was to go do some stalls with more rudder and go over to the towered airport to work on landings, especially soft field landings. That would also get me some radio practice and probably some cross wind landings given the forecast.
I was a little slow getting going, and ended up stopping back by the house, but finally I was ready to do the last preflight checks. I did the runup and noted that the amp meter for the alternator did not settle down. Historically, it osciallates wildly at startup but then calms down once the engine revs up. Well, I thought about it for a bit. On the one hand, it could just be being a little more finicky than usual, on the other hand my alternator could be about to die. If the alternator quits, the airplane does not stop flying. Eventually the battery will discharge, and then I would have no radios or lights.
I decided to take off and see if it improved in flight. I modified my lesson plan to do the stalls first and some turns and then re-evaluate before going to the towered airport. I did not think having my radios fail while talking to air traffic control was a good idea.
I did my stalls and turns. Both were much better than last time. But the amp meter continued its wild oscillations. So I decided I had better go home. I thought about practicing landings at Brookline, but then I realized the electric fuel pump which is used as a backup to the engine driven pump when landing and taking off would also suffer from the battery draining. So I just landed. It was not a very good landing because I was too busy worrying about the alternator.
Back on the ground, I called my instructor to see what he had to say. He suggested the alternator was probably still charging and had a few more tricks to get the amp meter to settle down. I turned the airplane back on and got the amp meter settled. So then I was just feeling silly. Unfortunately, I didn’t have enough time left before work, so I pushed the airplane back into the hangar.
Later that day, I heard the update on the alternator. Diagnosis at the shop had shown it needed brushes, windings, bearings, and diodes. So then I didn’t feel so dumb for having foreshortened my flight.