Simrad AP16 Rudder Response failure help?

[mrybas]

Hi,
I'm getting to leave French Polynesia to start the sail to New Zealand. I'm getting a 'Rudder Response Failure' alarm with my Simrad Ap16. I only get the alarm while sailing, when the wind picks up a bit in a gust and there is more weather helm and the AP is forced to work a bit harder. I also do not get the alarm when I disconnect the the rudder position sensor. However this puts the AP into 'Virtual Feedback mode' and it doesn't steer as well as the rudder feedback sensor. The connection from the rudder position sensor to AP computer are good. Does anyone have any suggestions?
Thanks!
Mike
SV Hartley currently Huahine, French Polynesia

[DeepFrz]

Have you tried resetting the AP? I see one post where that did the trick.

[mrybas]

I have reconfigured the AP (the procedure where you drive in a figure 8). Is that what you are referring to? If not how to you reset the AP?

[44'cruisingcat]

If it's happening under load, it's possible the A/P drive simply isn't turning the rudder enough. Maybe you could try moving the link from the tiller arm to the rudder position sensor further in toward the centre of the sensor, which would give an exaggerated indication of rudder movement.

[SilentOption]

It could just be faulty. I had a very new sensor fail then the new one showed up and it was bad. Figure the odds...
I would up sailing 1100 miles in virtual feedback the boat was making about a 20 degree swing the whole time.

I know that doesn't help..

[SilentOption]

If it's only happening under a load it could be your computer is getting hot and the only component affected is feedback.

[mrybas]

Thanks for the input fellas. I just cleaned the electric hydraulic pump brushes, which were pretty dirty. I'll go for a test sail in a couple days....fingers crossed that the problem is solved!

[44'cruisingcat]

Also make sure the wiring to the A/P control box and from there to the pump motor are adequately sized for the load.

[mrybas]

I went for a sail with the cleaned brushes yesterday. With the rudder position sensor hooked up, I repeatedly got a 'rudder response failure' alarm. Once I disconnected the rudder position sensor and the AP was in 'virtual feedback mode', the AP worked perfectly. It weird that having the rudder position sensor connected seems to weaken the power of the ram???

[Neptune's Gear]

The first thing to do is see if the message is correct! By using virtual feedback mode, the system "presumes" the rubber is moving - it may not be!
It could be that there IS a rudder response failure. What that means is that the AP is trying to turn, the pump is running, but the rudder has not moved within the timeout period. Can be down to air in the system, a faulty bypass solenoid, a stuffed hose that is expanding rather than pushing the ram, stuck ram, dodgy seals etc etc.
So, if it is repeatable, set it up, then watch the rudder stock - is it actually moving when the error comes up - the error says it is not.
You may be able to manually simulate a load by holding the wheel (if you wheel normally moves when on AP).....
Good luck

[mrybas]

When the rudder feedback sensor is connected, the autopilot is easily over powered in a slight increase in wind. You hear the AP 'groaning' as it does when there is a lot of load on the AP, then maybe 5-10 seconds later the 'rudder response failure' alarm. So the rudder is not moving the amount the AP computer is telling it to. It would seem like a problem with the hydraulic system somewhere.
Now if I disconnect the rudder feedback sensor, and the AP is in 'Virtual Feedback mode', in the same wind conditions, the AP works fine. The AP doesn't groan and doesn't have the lack of power as when the rudder feedback sensor is connected. However, it doesn't make sense that the rudder feedback sensor would have anything to do with the output of the hydraulic ram???

[DeepFrz]

Is it the pump that is groaning or the actuator that groans? Have you observed the actuator and pump while at sea? Could it be the actuator mounting assembly is shifting and binding? Have you cleaned and tightened every electrical connection to the AP and hydraulic pump?

Try (carefully) putting your hand on the pump while at sea and on the actuator assembly stationary part to check the feel of the action. It might tell you something. A mechanics stethoscope might be even better than feeling by hand.

[Neptune's Gear]

Actually it does have some. The rudder feedback unit effectivly controlls how fast and for how long the hydraulic pump runs for (it's a standard reversing pump, right? RPU 80, 160 or 300).
So with the rudder angle sensor connected the AP says for example, move to port. Pump starts but nothing happens, so AP says to pump "go flat out" still nothing happens = timeout.
Without rudder angle sensor, pump just runs for some time, and presumes helm moves as required. So the loading applied - Amount of pressure and volume the hydraulics produce is different in each case.
Does the noise seem to come from the pump unit or the ram?
If the pump has dodgy bearings, this could happen... Although if the pump is really bad it will likely overload the AP computer, which will fail with a Current Overload type message.

Which AP computer do you have - the J300X ? if so it can only supply 10A...and the pump (RPU80) can use up to about 40ams at stall...
Anyway, if you can tell me if the noise is from the pump or ram, we can probably fault find this a bit better!
Cheers
Matt

[Neptune's Gear]

Phil, you beat me that post! :-)

[DeepFrz]

Matt, we are both on the same track anyway.