Servo Power Switch - Requirement

[Rob_Erdos]

Folks,

I'm in the avionics shopping phase of my RV-6 project. It will have a dual 7" Skyview installation with autopilot and VPX-Pro. A have some concerns about this installation:

Autopilot disconnect is signaled to the Skyview system via software. In the event of a system malfunction, I have no easy means to compel an autopilot disconnect. This is especially true with the Vertical Power VPX electrical system installed, as I won't have direct access to mechanical circuit breakers. Consequently, I am considering installation of a SERVO POWER toggle switch on the panel. Is this a useful idea? Is there any technical reason why I couldn't do this?

Thanks in advance,

Rob Erdos
RV-6...in progress
Ottawa, Canada

 

[dynonsupport]

The disconnect is not just a software request. The disconnect button, which is required to be installed, goes direct to the servos and actually electrically interrupts power to the servo motors. This is only true as long as the disconnect button is down, but if you hold the button down, the servos are de-powered no matter what software requests. Also, the servos require continuous bi-directional communications with the screens to stay connected, so software lock-ups in the screens will actually cause a disconnect.

So, to end up with an AP stuck on, you'd need to have all the following occur at the same time:

1) Have software that was still running but ignored the disconnect (never heard of this happening)
2) Have the disconnect button be broken so you can't hold it down and keep the servo in disconnect.
3) Have the VP-X be failed so you can't cut power to servos
4) Be in a place where you can't afford to de-power the whole plane with the master switch to get the servos to stop.

Also, our servos are easily over-ridable by the pilot. It's totally possible to fly the plane any way you want with the AP engaged, even landing if required.

It's a solidly designed system that shouldn't need another level of disconnect redundancy.

 

[mmarien]

I put in an AP power switch because I seen it on several checklists and thought it a necessity. But I agree with Dynon that's it's not required on their system. The disengage/CWS button is required. I mounted mine on the stick and use it regularly.

You can turn off the power to the servos through the VP-X interface on Skyview if you need to. All the VP-X circuits can be managed through Skyview.

 

[Rob_Erdos]

Folks,

Your thoughtful replies are much appreciated.

The SERVO PWR switch will be deleted from the design.

Rob

 

[airguy]

I put in a circuit breaker for the servo power (no VPX in my plane), but that was simply to protect from an overcurrent scenario.