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- Mar 22, 2019
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We recently purchased a '67 PA-28-140/160 that looks generally to be in good shape. However, there are at least two issues we know of 1) windshield issue (posted separately) and 2) amp indication. This airplane has what looks like a newly rebuild Chrysler alternator (37 amps per the tag). Pretty small, but I imagine there are a few of those out there. I say "newly rebuilt" because it is absolutely clean and bright/shiny; I think it was replaced with engine rebuild about 10 years back and 150 engine hours ago. I can look through the logs to verify that, but they're at the plane right now.
Basically, the ammeter fluctuates continuously back and forth at taxi (say 1100 rpm) with an amplitude of about 20-30 amps and frequency of maybe 2 cycles/sec -- fast enough that the needle may not be fully responding. It is more vigorous at higher rpm, but I have not personally flown the airplane yet.
The prior owner says its "normal" (which I doubt), but we were willing to buy the plane and sort it out. He flew the airplane to us, about an hour flight. It did the same at his location when we looked at it. Resting battery voltage looks ok.
My question is: is this likely to be intermittent alternator brush contacts, bad VR, or is this normal, maybe due to no damping left in the meter? Prior owner says the VR was replaced with a solid state unit. If he left the OV relay in place, could it do this?
I don't know exactly where the VR and (possible) OV relay might be, I'm assuming under the dash like in a separate recent post? (I am gathering that if the OV relay is there, it should probably be removed)
Thanks
Ted
Basically, the ammeter fluctuates continuously back and forth at taxi (say 1100 rpm) with an amplitude of about 20-30 amps and frequency of maybe 2 cycles/sec -- fast enough that the needle may not be fully responding. It is more vigorous at higher rpm, but I have not personally flown the airplane yet.
The prior owner says its "normal" (which I doubt), but we were willing to buy the plane and sort it out. He flew the airplane to us, about an hour flight. It did the same at his location when we looked at it. Resting battery voltage looks ok.
My question is: is this likely to be intermittent alternator brush contacts, bad VR, or is this normal, maybe due to no damping left in the meter? Prior owner says the VR was replaced with a solid state unit. If he left the OV relay in place, could it do this?
I don't know exactly where the VR and (possible) OV relay might be, I'm assuming under the dash like in a separate recent post? (I am gathering that if the OV relay is there, it should probably be removed)
Thanks
Ted
