2015 RV-12
Rotax 912ULS
Dynon Skyview Touch
Garmin GTR 200
Bose A20 headsets (2)
During a recent annual condition inspection I removed and re-installed the fuel tank at least four times tracking down a very small fuel leak. I eventually replaced the fuel line that runs from the tank to the electric fuel pump. Flying the aircraft after that, the radio and headset were "loud and clear" on radio checks and had no discenible abnormal noise.
I also had a Skyview back up battery test that failed and that was not remedied with a routine charger. Following Dynon service recommednations, I disconnected the aircraft battery terminals and connected an external DC power supply to the positive cable and grounded it to the aircraft frame ground. I set the amperage to full and the voltage to 14.5 v for two days, then re-connected the aircraft battery cables to the battery after which the Skyview back-up battery test passed. OF NOTE, when reconnecting the battery cables I had accidentally connected the negative wire from the Oil heater to the positive battery terminal, and when I turned on the Master switch, got a brief spark and immediately turned the Master switch off. Fortunately everything seemed to be working normally afterward and I proceeded to do a test flight.
Before start up, I turned on the Master switch and waited until the Dynon system finished booting. Although there were no error messages on the screen and all seemed well, when I put on my headset, I heard a somewhat annoying whining sound in the background. The engine was still not running and neither magneto switch was yet turned on. The engine started normally, and the whining now seemed to increase and decrease in volume with changes in engine RPM. Radio check received a "loud and clear" from another aircraft 10 miles away and all incoming transmissions were as clear as usual. Incoming and outgoing transmissions both cancelled out the whining noise. The noise does NOT stop when I pull the electric fuel pump fuse.
In flight, the noise became nearly unbearable and would decrease in volume with the volume knob, but of course, that made incoming transmissions almost inaudible.
I recently spent several hours in the avionics and engine bays looking for loose wires, connectors, grounds, and bare wires and checking the headphone jacks for looseness or play. Some of the multi-pin avionics connectors required tightening of their screws, but none were loose. I dosconnected the antenna from the Garmin at the radio itself and the whine persisted. I checked the newly reoplaced ELT battery and its connections. The Garmin Receiver LED showed no evidence that the sound was coming from a spurious transmission.
The current voltage regulator is a Silent Hektik that I installed in late 2019 after failure of a second Ducati VR, and based on me having accidentally sent positive current its direction when reconnecting the oil heater wires backwards, I wonder if it could be at fault? Could it cause a whine when the Master is on but engine off? The voltage it shows at idle has always been a bit lower at 13 v, and when I ran the engine recently during my exploratory surgery, it was only showing 12 v.
I have not checked the antenna connection inside the aft fuselage but have no reason to worry about it specifically.
I also could have damaged the ignition switch with the crossed wire mess. Would that cause the problem? It certainly works normally.
I am thinking of getting the more recently approved voltage regulator. Anyone think it could be the culprit?
Rotax 912ULS
Dynon Skyview Touch
Garmin GTR 200
Bose A20 headsets (2)
During a recent annual condition inspection I removed and re-installed the fuel tank at least four times tracking down a very small fuel leak. I eventually replaced the fuel line that runs from the tank to the electric fuel pump. Flying the aircraft after that, the radio and headset were "loud and clear" on radio checks and had no discenible abnormal noise.
I also had a Skyview back up battery test that failed and that was not remedied with a routine charger. Following Dynon service recommednations, I disconnected the aircraft battery terminals and connected an external DC power supply to the positive cable and grounded it to the aircraft frame ground. I set the amperage to full and the voltage to 14.5 v for two days, then re-connected the aircraft battery cables to the battery after which the Skyview back-up battery test passed. OF NOTE, when reconnecting the battery cables I had accidentally connected the negative wire from the Oil heater to the positive battery terminal, and when I turned on the Master switch, got a brief spark and immediately turned the Master switch off. Fortunately everything seemed to be working normally afterward and I proceeded to do a test flight.
Before start up, I turned on the Master switch and waited until the Dynon system finished booting. Although there were no error messages on the screen and all seemed well, when I put on my headset, I heard a somewhat annoying whining sound in the background. The engine was still not running and neither magneto switch was yet turned on. The engine started normally, and the whining now seemed to increase and decrease in volume with changes in engine RPM. Radio check received a "loud and clear" from another aircraft 10 miles away and all incoming transmissions were as clear as usual. Incoming and outgoing transmissions both cancelled out the whining noise. The noise does NOT stop when I pull the electric fuel pump fuse.
In flight, the noise became nearly unbearable and would decrease in volume with the volume knob, but of course, that made incoming transmissions almost inaudible.
I recently spent several hours in the avionics and engine bays looking for loose wires, connectors, grounds, and bare wires and checking the headphone jacks for looseness or play. Some of the multi-pin avionics connectors required tightening of their screws, but none were loose. I dosconnected the antenna from the Garmin at the radio itself and the whine persisted. I checked the newly reoplaced ELT battery and its connections. The Garmin Receiver LED showed no evidence that the sound was coming from a spurious transmission.
The current voltage regulator is a Silent Hektik that I installed in late 2019 after failure of a second Ducati VR, and based on me having accidentally sent positive current its direction when reconnecting the oil heater wires backwards, I wonder if it could be at fault? Could it cause a whine when the Master is on but engine off? The voltage it shows at idle has always been a bit lower at 13 v, and when I ran the engine recently during my exploratory surgery, it was only showing 12 v.
I have not checked the antenna connection inside the aft fuselage but have no reason to worry about it specifically.
I also could have damaged the ignition switch with the crossed wire mess. Would that cause the problem? It certainly works normally.
I am thinking of getting the more recently approved voltage regulator. Anyone think it could be the culprit?
