If the autopilot is over=powered the auto-trim will run to
try to get control forces back in the acceptable range.
This will place the airplane seriously out of trim. A pilot
can over-power the autopilot, but if this is done it should
be either as a demonstration during checkout or in response
to an autopilot actuator run-away. The pilot should
maintain attitude control, over-powering the autopilot while
they
1 push the disconnect button
2 pull the circuit breaker
3 manually retrim
4 land ASAP



--
James H. Macklin
ATP,CFI,A&P

"Robert M. Gary" wrote in message
oups.com...
|
| Mxsmanic wrote:
| In simulation, if I set the autopilot to maintain the
altitude, and
| then try to change pitch with the controls, the control
surfaces
| barely move, and I can hardly have any effect on pitch.
|
| I think this is a limitation of the simulator. My guess
is that, in
| real life, the autopilot continuously adjusts trim, and
so, if you try
| to change pitch with the yoke, the A/P retrims to cancel
out your
| efforts, and the net effect is that you can change
pitch, but you must
| exert very high control pressures to do it (in order to
overcome the
| trim that the A/P is applying to neutralize your
efforts).
|
| Is this correct? I can see why this is difficult to
simulate with
| controls that don't provide feedback, but I want to make
sure that I
| understand the difference between the sim's way of doing
it and the
| real thing.
|
| It takes pretty minimual control to over power the
autopilot. However,
| if you disrupt it a great deal (make a big pitch change
for instance)
| the autopilot may overcorrect a few times before settling
back to the
| correct pitch. The ability to return to the correct pitch
with minimal
| over correcting is a function of the quality of the
autopilot.
| Sometimes when you make changes such as lowering flaps you
need to
| "help" the autopilot but holding the yoke in the right
place for a bit
| until the autopilot figures out what is going on. This
even with the
| more expensive autopilots (like the new KAP140).
|
| However, it is very easy to hand fly the plane while the
autopilot is
| on. The Cessna training instructors told us that they
routinely hand
| fly procedure holds on approach w/o changing the mode on
the autopilot,
| just over powering it.
| In my plane I'll hand fly through turb but I'll leave the
autopilot on
| because it gives me a nudge back to course (i.e. I can
feel it trying
| to pull me back on course). If I take my hands off during
turb though
| it will make the turb worse.
|
|
| -Robert
|