Strange electrical issue - Need Help - GRT - VPX

Fearless · #1 08-07-2017, 04:38 AM

I am having an issue where when I try to start my plane and while idling and not moving, I get an overspeed condition on my flaps. I have talked to Chad about this and he thinks I have an issue with my GRT Sport on the airspeed readings side of the house. I have gone into the VPX Configurator and set my flap ranges to 0 as well as set the Overspeed setting to 300 MPH which I will never hit. Because the flaps are wired into the VPX box I haven't tried to set the flaps to disabled. I can clear the fault through the Configurator but it keeps coming back on occasion. The only way to clear the fault is through the Configurator and I can only do that on the ground with the computer I have the software installed on. I have not seen anything in the GRT Sport setup to make me think its being caused/triggered there. I bought the VPX Sport to use the overspeed functionality as well as monitor my electrical system but this problem is causing me to regret that decision. I would like to have this solved before the first flight on the plane and not have to worry about a no flap landing. I do not have the Ray Allen flap position indicator on my plane.

rv7charlie · #2 08-07-2017, 02:01 PM

The 1st answer needed for the question is, does it happen when you try to start the plane, or when idling and not moving, *after* start? Very different circumstances.

jwilbur · #3 08-07-2017, 02:06 PM

VP-X has a simulation mode. If you turn off the efis, you can turn on the simulator from the software and set the airspeed and some other parameters. If the problem persists it's with the VPX. If not it's either with the efis or the communication between the efis and the VPX.

Another thing is make sure you ARE NOT in simulation mode if the efis is turned on or you will get unexpected issues.

Fearless · #4 08-08-2017, 04:23 AM

I only get alerted to it after the plane has started and not moving. It shows as a fault on the EFIS screen.

cjensen · #5 08-08-2017, 09:48 AM

Mike, I don't remember if we talked about what is hooked up to the VP-X when we were on the phone. Is the computer/configurator always hooked up when you are seeing the overspeed fault? Or are you getting it with just the EFIS?

The VP-X can't generate an airspeed reading without the configurator in simulator mode, essentially a "read-only" function from the EFIS.

Fearless · #6 08-08-2017, 10:32 AM

Chad,

Its always on the EFIS. I have never had the laptop/configurator plugged into the VPX box with the engine running.

I think I am going to change my VPX settings to where my EFIS is turned on through the Avionics switch with my COM and transponder which would not be on when starting the engine and see if this has some effect.

I had the EFIS being turned on with the Master and this might have an undesired effect on the EFIS while the engine is trying to start.

Also as an aside note I did get my alternator field problem resolved.

RViter · #7 08-09-2017, 09:45 AM

"... I would like to have this solved before the first flight on the plane and not have to worry about a no flap landing. I do not have the Ray Allen flap position indicator on my plane."

I made the first 3 Phase 1 landings as "no flap" and in fact, didn't intend to extend flaps on the first flight. (Limited scope to other tests and kept it short). The 2nd and 3rd were unintended due to having set the 'airspeed limit' too low and the flaps would not extend with airspeed above "1" kt. Changed the limit and it's fine now. All my flap settings are with the Ray Allen POS-12 so the SkyView (in my case) only displays the position, but does not control it.

Does your GRT display or "integrate" with the VP-X? If so, is there a 'soft key' showing the current/circuit status for the flap motor? I discovered too late that the soft key UP/DOWN on my SkyView would ignore the VP-X limits and allow flap operation regardless of VP-X limits. Is that an override option?

Fearless · #8 08-10-2017, 04:40 AM

Gary,

The state of the electrical system from the VPX does display on one of the engine pages on the GRT Sport. If memory serves me I believe it only displays if the switch is enabled or not.

cjensen · #9 08-10-2017, 07:20 AM

Quote:

Originally Posted by Fearless

I think I am going to change my VPX settings to where my EFIS is turned on through the Avionics switch with my COM and transponder which would not be on when starting the engine and see if this has some effect.

I had the EFIS being turned on with the Master and this might have an undesired effect on the EFIS while the engine is trying to start.

Also as an aside note I did get my alternator field problem resolved.

The EFIS pin (J12-9) is factory pre-programmed to be always on with the master switch so you have electrical info from the VP-X before the engine is started. There is no connection between engine start and airspeed to generate the error you are seeing.

You can put a switch in to turn the screen off prior to engine start if desired, but it will always turn on when the master switch is cycled.

Glad to hear the alt field issue is resolved.

MCA · #10 08-16-2017, 11:27 PM

Mike,

Set the 'max flap speed' setting in the configurator to 0 and that will disable the over speed alarm during testing. Does that make the issue go away?

If so, then you may have the 'over speed position' set incorrectly.