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APS4A altitude preselect system

RNC

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Hey folks, I have switched autopilots from an STEC55 to a KFC225 so that means I can't use this anymore, because the 225 has integral preselect.

It was in my Commander for about 2 years and 200 hours.

http://www.avionik.de/en/avionics/avsr-products/aps4a.html

Summary:

For the listed compatible autopilots it will provide altitude preselect capability with the caveats of...

1) It requires an altitude bug with an annunciation output so... Aspen or G500/600 or similar is the most common application. At minimum, an altimeter with a bug and an annunciation attached to the bug.

2) It requires cutting a hole in the panel for the arm/disarm switch. The switch is included. It's a square Eaton #96182 push-button type switch.

3) This is a 28v model.

How it works:

The manner in which you climb or descend is still controlled by the autopilot head unit, whether that be setting pitch or setting vertical speed or whatever. The way you do that in your airplane with your autopilot stays the same.

When the altitude set on the bug is reached and the annunciation fires on the G500/600 or Aspen panel, this box senses the annunciation and triggers alt hold mode on the autopilot head unit. After it does so the unit is automatically disarmed and doesn't do anything else unless you arm it again.

The result of this is a very simple and effective pre-select system. You can engage the system in any order of button presses that you like. Personally, when I was using this I started the climb or descent right away with vertical speed control after I got cleared higher or lower by ATC, then after the airplane was doing its thing I programmed the bug and armed the alt capture after the fact. If you prefer to do it the other way around and set the bug + arm first and then start the climb or descent afterward, go ahead, it doesn't care.

The flexibility of being able to program your climbs/descents in any order you like is what makes this the best preselect system I've used.

Pics here

The retail on this was 1750 dollars ($1200 for the box and Dallas Avionics is the only supplier of the switch, which they charge $550 for).

Looking for 1200.
 
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Orest @ CYFD

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I would just echo, the APS4A altitude preselect is the unit of choice for an STEC. I love mine. Uses your ASPEN or G500 preselect altitude, no separate altimeter to set, always levels perfectly, not order sensitive for the button play, very small panel footprint.

* Orest
 

rrc1962

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Is it hard to install? Something the elves could do (with an IA checking the results)?
 

Orest @ CYFD

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The unit is dead simple. When the momentary closure Eaton button is pushed to arm the system, it looks for a contact closure from the ASPEN which is triggered by the altitude matching the indicated preset. That drives a relay that closes a circuit, which flips the STEC A/P from ALT/VS mode to ALT (hold) mode.

You have to mount the switch in the panel, the box behind the panel somewhere, provide fused power and run the wires. You do need access to the ASPEN and A/P wiring diagrams, you don't want to let out the smoke from your units.

There is paperwork in involved, so an IA is mandatory. You do need to be sure that is transferable.

* Orest
 

RNC

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Edited the original post, slight mistake. These are voltage specific due to a connection to the lighting bus. This is a 28v model.

These are STC'd under the Aspen and G500/600 STCs, there is no paperwork to have but the pilot manual from the manufacturer, which I have to send with the unit so...
 
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rrc1962

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The

You have to mount the switch in the panel, the box behind the panel somewhere, provide fused power and run the wires. You do need access to the ASPEN and A/P wiring diagrams, you don't want to let out the smoke from your units.

There is paperwork in involved, so an IA is mandatory. You do need to be sure that is transferable.

* Orest
Might not need to get into the Aspen. The PFD is connected to a so alert on the panel that goes off when (1) Preset altitude is reached or (2) Minimums are reached. If the input the APS4A is voltage and not a dry contact, I could probably drive it from the same circuit.

Wish I could use this used one, but I need 14V.
 

Orest @ CYFD

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Might not need to get into the Aspen. The PFD is connected to a so alert ...
No, the sonoalert goes off as a 15s warning, not much use for this.

It is a separate circuit.

* Orest
 
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