L

lpeeds

Member
I just powered up my Skyview for the first time and as soon as I turned on the Master, before turning on the Avionic or Autopilot there was a continuous loud noise coming from behind the baggage bulkhead. The noise sounds like a loud rattle or vibration. I'm sure I should have checked the Skyview before sealing the bulkhead and installing the fuel tank but I don't remember seeing anything stating the order of things at this point in the build. Basically the plane is built. Just the final checking remains.

Any ideas on what I'm looking for when I open up the back end again?

Paul Eeds
#120506
 
lpeeds said:
I just powered up my Skyview for the first time and as soon as I turned on the Master, before turning on the Avionic or Autopilot there was a continuous loud noise coming from behind the baggage bulkhead. The noise sounds like a loud rattle or vibration. I'm sure I should have checked the Skyview before sealing the bulkhead and installing the fuel tank but I don't remember seeing anything stating the order of things at this point in the build. Basically the plane is built. Just the final checking remains.

Any ideas on what I'm looking for when I open up the back end again?

Paul Eeds
#120506
Click to expand...

Behind the baggage bulkhead? The only things powered back there are the ADAHRS, the trim servo (way in the back), and the roll servo. Very interesting. Could it be something up front and the sound is resonating to the back perhaps?
 
To troubleshoot, you might try pulling one circuit breaker at a time and see if you can isolate the source. If it is coming from the back of the plane, it is unlikely to be the SkyView. A broken SkyView fan blade might sound like that, but would be from the front of the plane.

-Robert
Dynon Avionics
 
You do know that the fuel pump runs continuously when the master is turned on? It makes a very loud rattle especially if it is running dry.
 
Last edited:
Tony_T said:
You do know that the fuel pump runs continuously when the master is turned on? It makes a very load rattle especially if it is running dry.
Click to expand...

I bet Tony has the winning solution here. A quick pull of the fuel pump fuse will confirm this. I'd bet Tony is right on the money, and the sound from the pump just seems as if it is coming from aft of the baggae bulkhead! Good call, Tony.
 
I suspect that most of us initially test the Fuel Pump circuit to ensure that it works and then we pull the FP fuse until we have fuel in the tank. Rumor has it that running a FP while dry is not good for the pump's inards (besides, it's very noisy).

Keep in mind that the FP circuit also supplies power to the two avionics cooling fans located on the forward shelf. I guess that if one were to test-run the avionics for a longtime with the avionics cover panel in place and high ambient temperatures, the absence of the two cooling fans might cause a heat problem for the avionics bay.

Another "noise in the back" could be the autopilot's roll servo ratcheting. As stated earlier, just start pulling fuses until the noise goes away! :D
 
Noise when master on

Thanks for all the suggestions. I just went out and checked and it is the fuel pump. I will go out in the morning and get a few gallons of 100LL and hopefully that will solve the problem. Thanks again.

Paul Eeds
#120506
 
Fuse

Paul,
Pull your fuel pump fuse while you are doing all the check outs. The cooling fans won't run while the fuse is pulled so don't let that fool you. Ask me how I know?
 
Cooling fans

Just a note for information. I did pull the fuel pump fuse. My cooling fans were still running.

Paul Eeds
#120506
 
lpeeds said:
Just a note for information. I did pull the fuel pump fuse. My cooling fans were still running.

Paul Eeds
#120506
Click to expand...

There are three different fans.
The two fans mounted to the panel deck are indeed powered by the fuel pump circuit and will stop when you pull the fuse (if everything is wired up as designed).
.
There is a third fan in the AV-5000o box that is powered by a different circuit.
 
... and don't forget the two small cooling fans mounted on the backside of the SV display. These two fans are apparently controlled by a thermostat inside the SV display and go on/off as needed to cool the SV display's innards. The display even shows you the unit's internal temperatures and the fans' respective RPMs!
 
I was afraid someone would ask that question! :eek: I don't have Dynon's manuals at my disposal at this moment, but the procedure for finding the appropriate screen page is in there. I found it by looking at all of the SV's various Setup screens and going through each of the sub-screens. Lo and behold there is a screen with the fan temperatures and RPMs. Great stuff to fiddle with on those long cross-countries! :)
 
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