Advanced autopilot

I was flying this approach last night for practice.
http://204.108.4.16/d-tpp/1105/00785R26.PDF
all was going well on the autopilot
i put in 1450 for minimums(cannot select 1420-if would be nice to be able to put in actual minimums)
i put the MAP altitude in 4400
plane leveled off at 1420 but when i added some power it started to climb before reaching the MAP
i'm using a 430w
is this normal?
What should the autopilot do at minimums?

alan

If you add a significant amount of power at the MAP, it will cause the airplane to climb a bit. Remember the servos are holding altitude so when you add a bunch of power, it takes some time for the servos to compensate for the increase in power and keep the aircraft level. It also depends how much power you are adding. If you are at 18" in a stabilized approach and bring it up to 20" at the MAP, it shouldn't do much. If you are at 12" in the approach and bring it up to 20", it will probably pitch a bit before it stabilizes.

We did debate the minimum altitude scale and determined that 50ft intervals were the most convenient and prudent option. 25ft increments caused it to take too long to run up and down, 100ft increments were too large. Realistically, most of our customers don't fly in IFR conditions where 20ft means landing or going missed.

trevor i was about 12 inches and added power to about 19 inches to level off. At the MAP should the ap start the climb if I unsuspend the 430w?
Alan

Yes, if you press SUSP on the GNS-430W upon reaching the MAP waypoint it will resequence the 430W and 4500 to the next waypoint and the autopilot will go from V:MINS to V:ALT and start climbing to the altitude bug set.

Thanks. While on the subject how about adding a GA( go around) feature to the autopilot?
Alan

Another AP question Trevor. If at the MAP there is a course change say climb to 4000 then turn toward a fix will the AP do that?
Alan

I'll mention the TOGO feature to the software guys. That is nice to have, its common practice on larger aircraft.

Quote:

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If at the MAP there is a course change say climb to 4000 then turn toward a fix will the AP do that?

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The autopilot won't do it automatically. You'd have to be in HDG mode to fly the current heading until reaching the desired altitude.

trevor,
i was reading the vsvg manual and it says while doing an ils approach hitting any button on the ap will start a 500fpm climb .
Alan

Alan,

Are you sure you were looking at the VSVG manual? The Digiflight II VSVG isn't capable of doing ILS/LOC/VOR/NDB approaches. It can only accept deviation commands via GPS.

Trevor,
I should have said glide slope not ils. Here is the link to manual.http://www.trutrakflightsystems.com/...tingManual.pdf
read page 10-11. vertical mode and missed approach.
Alan

Those instructions are for the DII VSVG if you have it coupled directly to a GNS-430/530/480/650/750. It is pretty limited in what it will do connected only to one of those units. When connected to the EFIS and in EFIS mode, it will follow the HDG bug, ALT bug, fly VOR/ILS/LOC/GPS approaches, and it will allow it to level at the MINS bug. When you hit SUSP on the GPS, it will auto-sequence to your MAWP and the EFIS course needle will auto-slew to the new course and give you CDI indication. It will also cause the EFIS to stop holding at the MINS bug and change the vertical mode to V:ARM, causing the autopilot to start a climb to the ALT bug which you would have set previously for your first altitude on the missed approach procedure. You can fly an entire approach from Enroute to the Missed Approach without touching anything other than the altitude bug and your throttle.

trevor,
thanks good summary and I'm learning the EFIS. Now how about holds?
Alan

It will fly the holds really well! I did one yesterday actually on the RNAV-35 into KCVO and it did the whole missed procedure and held at SHEDD as published.

This only works once you're coupled to the glideslope on an approach. In the case of the VSGV, it can only be a GPS approach. So, if you're flying an ILS with the EFIS, the missed approach feature won't work as the AP doesn't know that it's coupled to a glidslope since the EFIS supplies the vertical steering commands for the ILS glideslope.

EDIT: Maybe in the future I'll read page two before posting. Trevor was already on top of this. :)