low voltage on my 503
Posted: Tue Mar 27, 2018 9:06 pm
Backto my voltage situation. I am running a 503 oil injection DCDI, pulse fuel pumpand an electric fuel pump (switch controlled on the panel). I have a GrandRapids EIS that was set up before I got this Gull 2000. So about a week ago thered light comes on during short pattern flight: this indicates system voltagebelow 11v. The light is intermittent: not much rhyme or reason to it coming on orgoing off: I first thought it was rpm related.
Inmy search for an answer I sort of lucked into a check. While parked, engineoff, I shut off all switches: master, EIS, fuel pump (which is normally off allthe time and used only when initial pre-start up to fill the fuel lines and carbbowls) and the ACS switch (5 position key operated known asAirCraftSpruce). With main and EIS on Isee 12.2v displayed, then as I rotate the ACS on over to the Both position Inotice the voltage dropping. And I couldsay similar for the Fuel Pump but I would expect voltage to drop with the pump on.
Irecall 2 yrs ago being at AirVenture Oshkosh 2016 and attending a talk by BrettLawton of Leading Edge Airfoils in which he mentioned spending a lot timechasing down what appeared at first to be an engine problem but was found to bea faulty ACS switch. My symptoms are not exactly like he described but I talkedwith him via phone yesterday just to get his view and to let him know myproblem.
Anyway,shortly I will remove that switch and replace it with two toggle switches (MagI & II) and a push button starter switch (all from B&C). I will follow with my views after thechangeover. I write this now to ask if anyone in the group has been in asimilar situation. By the way, Lawton commented that voltage regulators tend tofail all the way and typically do not behave in the way this voltage is nowpresenting. (As an aside it seems to me that the only way a voltage drop willhappen is that if there is a load (perhaps a short) and my system when inflight has only the load of the EIS which has to be tiny by comparison to thebattery output.)
GG
Inmy search for an answer I sort of lucked into a check. While parked, engineoff, I shut off all switches: master, EIS, fuel pump (which is normally off allthe time and used only when initial pre-start up to fill the fuel lines and carbbowls) and the ACS switch (5 position key operated known asAirCraftSpruce). With main and EIS on Isee 12.2v displayed, then as I rotate the ACS on over to the Both position Inotice the voltage dropping. And I couldsay similar for the Fuel Pump but I would expect voltage to drop with the pump on.
Irecall 2 yrs ago being at AirVenture Oshkosh 2016 and attending a talk by BrettLawton of Leading Edge Airfoils in which he mentioned spending a lot timechasing down what appeared at first to be an engine problem but was found to bea faulty ACS switch. My symptoms are not exactly like he described but I talkedwith him via phone yesterday just to get his view and to let him know myproblem.
Anyway,shortly I will remove that switch and replace it with two toggle switches (MagI & II) and a push button starter switch (all from B&C). I will follow with my views after thechangeover. I write this now to ask if anyone in the group has been in asimilar situation. By the way, Lawton commented that voltage regulators tend tofail all the way and typically do not behave in the way this voltage is nowpresenting. (As an aside it seems to me that the only way a voltage drop willhappen is that if there is a load (perhaps a short) and my system when inflight has only the load of the EIS which has to be tiny by comparison to thebattery output.)
GG