You still also get the banana bar in your setup correct? That's a pretty easy "manual VNAV" method to follow if you don't have actual VNAV, or are in a position where a VNAV segment isn't available. I find it very useful, maybe more so than VNAV (you're kept high on descent into your field and you just dial in your desired altitude and put the banana right where you want to be at that altitude). Yes VNAV mode is easier, but not having it shouldn't be a deal breaker. And maybe at some point Garmin will release their DAP.

Chip-

[quote="Chip J Grueter"You still also get the banana bar in your setup correct? That's a pretty easy "manual VNAV" method to follow if you don't have actual VNAV, or are in a position where a VNAV segment isn't available. I find it very useful, maybe more so than VNAV (you're kept high on descent into your field and you just dial in your desired altitude and put the banana right where you want to be at that altitude). Yes VNAV mode is easier, but not having it shouldn't be a deal breaker. And maybe at some point Garmin will release their DAP. [/quote]
Yes, you get the "blue banana" along with VNAV guidance on the VSI. Just roll the AP pitch wheel until your VSI lines up with the magenta carat and you're all good. She flies STARs and everything.

Just to spell it out, it will do coupled RNAV and ILS as well as synthetic (Garmin visual) approaches.

One additional point - there are 2 STCs for retrofitting Garmin in the 500 series: Columbia/Blackhawk and JetTech. One thing I like about the JetTech is that they use the Mach display to let you target a VS or IAS and adjust it with the AP pitch wheel. In the Columbia/Blackhawk you have to manually pitch to the VS or IAS that you want and it will hold it.

I like this because as you climb your IAS decreases (there is a table for cruise climb IAS target vs altitude) so I can adjust the IAS target during the climb. Yes, it's pretty easy to just pitch manually, but as a single pilot I like the safety net of IAS - in case I get distracted doing other things the plane will never get slow.

Others have described the capabilities of the SPZ-500 pretty well, and I agree it’s generally a robust autopilot.

One “gotcha” is that on the non Primus birds you have to arm the altitude select. Not a big deal but it can definitely bite you. I’ve also found that the IAS mode works on about 50% of the birds I fly. Some airplanes you can set the VS/IAS on the PFD but on bird with mechanical AIs you’re generally winging it.

The Primus 1000 birds with the a universal FMS will do vertical navigate and they fly “descend via” clearances quite nicely. There is some workload to flying a descend via on a SPZ500, especially without the Garmin PFD, but it’s not hard per se, just more challenging then hitting VNAV on my Garmin AP in the King Air.

Robert

For go around, hit the GA button on the left throttle.
Mike C.

A little thread drift:

My Twin Bonanza has a King KFC-300 autopilot/flight director. It is a King Air/Citation level autopilot, which is only installed in my TwinBo because it was once owned by King Radio, who used it as a testbed and demo airplane. As I often quip, I fly the world’s slowest King Air panel.

It is a completely analog device, made with mostly discrete components and the odd integrated circuit. Oh, and gears…lots and lots of little clockwork components connecting little DC motors.

It can do a lot of what a modern Garmin a/p can do: intercept the localizer and glideslope, fly coupled approaches, preselect an altitude and then climb in either VS or IAS hold, capture a nav track, and of course things like altitude and heading hold.

Not to disparage the truly incredibly capabilities that Garmin has brought to GA, but this 50-year-old autopilot is completely described by the two-foot-wide shelf of maintenance manuals. I was able to figure out and fix why my IAS hold wasn’t working without visiting an avionics shop.

Given the vintage and target market of the SPZ-500, I suspect it is built much the same way.

Yes, I get the "banana" which shows the point in front of you where you will reach the altitude preselect at current speed and vertical rate. It is a great judge of how your climb/descent is doing.

Also, the flight plan can be programmed with VNAV guidance where you get a "GS" like needle next to the altitude and if you track the needled you will reach the preselect altitude at the crossing point. The VNAV feature of the GTN is dandy.

The thing the SPZ500 doesn't do is track the VNAV guidance, so you have to set pitch, VS to track it, and play with power to get the speed you want. There are technical pathways to doing that, but with the coming of digital APs, that's going to be the best way to do it.

Mike C.

It is. The SPZ 500 is analog through and through. Lots of op amps and various discrete logic circuits for mode engagement. I have some schematics for the some parts of it I manage to find.

In my setup, I have the FD box and the AP box. The air data box is gone (JetTech STC keeps it) and all the attitude data comes from the Garmin sensors.

When a digital AP is available, I will be installing it. That will save about 100 lbs. I count 13 boxes I can take out, including the entire AC inverter system (with two inverters and fail over relays). The AP and FD are the last two things that use the main AC power on the airplane.

I will also be able to remove the radar altimeters, a Collins ALT 50B. The SPZ needs it, I'd be happy with the more accurate and equipment free AGL readout on the G700 TXi.

The SPZ is a nice autopilot that is still very maintainable today. But I want a digital AP, with VNAV, less boxes to maintain, and 100+ lbs of more useful load.

Mike C.

To expand on this, the SPZ 500 cancels ALT SEL if you change the target altitude. This is because it can't be tracking that while you are adjusting it, that would cause gyrations. So the FD/AP simply cancels ALT SEL when you change target altitude.

If you forget to reenable ALT SEL, you fly right past your target altitude.

So the habit you develop is to change the target and immediately hit ALT SEL after it is set.

A digital AP will handle this better since it can put program logic around the setting.


The sims also have problems with this.

IAS hold is a very tricky control loop due to the inertia of the plane.

Mike C.

It is. The SPZ 500 is analog through and through. Lots of op amps and various discrete logic circuits for mode engagement. I have some schematics for the some parts of it I manage to find.

In my setup, I have the FD box and the AP box. The air data box is gone (JetTech STC keeps it) and all the attitude data comes from the Garmin sensors.

When a digital AP is available, I will be installing it. That will save about 100 lbs. I count 13 boxes I can take out, including the entire AC inverter system (with two inverters and fail over relays). The AP and FD are the last two things that use the main AC power on the airplane.

I will also be able to remove the radar altimeters, a Collins ALT 50B. The SPZ needs it, I'd be happy with the more accurate and equipment free AGL readout on the G700 TXi.

The SPZ is a nice autopilot that is still very maintainable today. But I want a digital AP, with VNAV, less boxes to maintain, and 100+ lbs of more useful load.

Mike C.

I believe this may be a difference between the JetTech and Columbia STCs. As long as ALTSEL is still in ARM status I can change the altitude preselect on my PFD and nothing will change on the FD mode panel. The one gotcha is that if ALTSEL has moved into CAP mode and you change the altitude target it becomes a bucking bronco (the gyrations to which you refer). So I am in the habit of doing like you said, hit ALTSEL, dial the new altitude, hit ALT SEL again.

I have an SPZ500 and it tracks VNAV guidance...? I do it all the time. Works just like a glideslope.

I have an SPZ500 and it tracks VNAV guidance...? I do it all the time. Works just like a glideslope.

I think you're thinking of shooting an ILS or an RNAV approach and receiving vertical guidance. Yes it does that, but these do NOT fly a STAR with the associated altitudes to hit, automatically.

Quick note - I am pretty certain the Columbia STC is not available for the 501, only the 500 Not sure why they did that - but didn't extend STC to include 501. Jet Tech is the only option for the 501.

Matt

Correct, it will not track the vertical guidance of a STAR, but it does RNAV approaches very well.