AP Fault???

Hi,

I've had it occur again whereby I can be in a high altitude hover, with the Shkval in Turn-To-Target mode, when the aircraft will start slowly pirouetting, followed by the AP dropping out (all lights off except ALTITUDE).

I'm not sure which is first - the pirouetting or the AP disconnect, but there is no alert to this, except for when the Shkval reaches its gimbal limits and I'm suddenly not looking at what I should be.

I'm not touching the cyclic or collective, and can usually hover quite happily, but it will do this sometimes.

Anyone notice this? Note this is occurring at high altitude (e.g. 1600 meters), so isn't because I'm too low to the ground or anything.

Can turbulence cause this?

Best regards,

Tango.

How are you hovering..autohover or manual trimming? I would get this in autohover all the time, it doesn't seem to happen when manually trimming the helicopter to a hover.

Autohover.

It's fine most of the time.

Best regards,

Tango.

What was your rotor RPM? Did you have main hydraulics failure?

And no, turbulence can't cause this.

I have this happen too. Auto pilot is trying to kill me. Just disengages when in a hover. I'm usualy heads down looking at tv, by the time I realize its off, I'm spinning wild out of control.

Why isnt there some audible warning when autopilot kicks itself off? Airliners give an audible cue, so does an F16. Pretty critical (and timely) bit of information to know.

And WHY does the autopilot disengage itself?

Radar altimeter going awol? Isn't there a max height for it?

I have this happen too. Auto pilot is trying to kill me. Just disengages when in a hover. I'm usualy heads down looking at tv, by the time I realize its off, I'm spinning wild out of control.

 

Why isnt there some audible warning when autopilot kicks itself off? Airliners give an audible cue, so does an F16. Pretty critical (and timely) bit of information to know.

 

And WHY does the autopilot disengage itself?

Post a track, it's not clear what you're doing from your explanation.

The AP will kick off when the helicopter is out of parameters. The question is, which parameter was passed and how?

Good question. I hovered for a good 15 mins last night without issue, but when I'm in the middle of using the Shkval in Turn-To-Target Mode - that's when it does it.

Best regards,

Tango.

How far off the set hover point had you gone before the drift off from pointing at the Shval target & eventual AP failure?

I think if you drift away too far, the AP starts having trouble correcting, starts to impart yaw, then eventually drops out altogether.

No this happens when she is steady as a rock. For no reason i can determine all the autopilot channels bar the Altitude disengage. What parameters can disengage the autopilot? might help knowing them to find the problem. Next time it happens I'll post the track.

Nate

I think I've seen this as well. I think the spinning was caused by the Shkval pointing too straight down. When I hit the lock button it said 0.9 for distance and I was 400 or 500 meters up. Don't know how I got in that situation, but I guess I didn't establish a perfect hover, and thereby got too close to position Shkval was looking at. Just my 2 Eurocents.

Hmm the auto turn to target is only a yaw maneuver. No pitch is commanded. If the Vikhr launchers can't point down that far, oh well says the autopilot.

Are you sure you don't have two commands bound to the same joystick button?