Old issues from purchase of plane…..all grounds checked for low resistance. As with most vintage aircraft, many loads are grounded to chassis/fuselage and I have ran a grounding bus from batteries for low resistance sink and moved all avionics to that. I’m not likely spending the dinero to up grade to LED system as I rarely fly it at night, although all other lights are LED due to engine EFI. …
I upgraded other original c172 lights to reduce draw should I experience alternator failure as engine is electronic fuel injected and needs battery power to keep running…. So it extends my flight time a bit should being needed….. the LED beacon light also caused this issue until I found a different led brand that didn’t …. All non aviation LEDs so wasn’t all that costly.
These older Whelan strobes, like most GA stuff are from the 1950s 1960s, use capacitors to release significant energy in short pulse, and with so mush stuff common chassis grounded, this energy finds it way to other components.
I expect revisit the ground strobe wires is path of least resistance, no pun intended. The plane is a 1969 and if it could talk, I would keep you up all night. A lot of less than great repairs, upgrades, and mods over its life, with service as trainer and rental. When I got if, it had a inop huge and heavy ADF and left over wires from earlier stuff thy were never removed….i reduced weight by 20+ pounds after removing the ADF and seemingly miles of unused wires from stuff long gone. May have left some wire that’s transferring strobe energy back into ground somewhere.
The plane was only supposed to be a test bed for a new engine design and used for certification so we never put much interest into stuff like this. It’s now mostly used to fly around for proficiency and fly-ins so these little things come to notice. A couple of local CFIs flew it to Oshkosh this year and complained bout the noise on the long flight, so I put the issue on my to do list.
