Piper Autocontrol autopilot with Garmin 430W
OK, call me stupid. I have recently purchased an Archer II with a Piper Autocontrol autopilot and a Garmin 430W. I did not receive training on how to drive the autopilot with the GPS. While I completely understand how to use the HDG mode to drive the autopilot, I don't know how to control the autopilot with the GPS. I understand that I have to set the little toggle to NAV1/GPS and set the autopilot to NAV mode, and I thought the GPS/VLOC had to be set to GPS, but I don't know how else to drive it to the selected destination. Any help would be appreciated.
Comments
Then, to make the AP track it you need to be certain it is connected to the AP. Go up to a safe altitude and put some leg in the 430 direct to somewhere. Set the AP to GPS. In the case of your type AP (same as mine) you also need to put the heading bug on your DG at or near the heading of your planned route. I have found if you put the bug at exactly the same heading, the plane will rock back and forth gently... and if you put the bug about 5 degrees left or right of the direct GPS heading, the plane will zig zag much less and be "better". Even in track mode set to GPS, the AP that you have has a strong desire to favor the bug over the mauve line on the 430. So long as the bug is at within 20 degrees of the 430 direct mauve line heading... it will track the mauve line, however, again it seems best to be within about 5 degrees. If running a plan the has waypoints that involve turns, it is needed to change the bug when you cross those waypoints to within about 5 degrees of the new heading.
Anyway, set the AP to GPS, put the bug in range, and turn it on. See if it tracks the mauve line. To verify if it is connected to your VOR/LOC as well, set it to that and get the NAV tracking some radial. Center the OBS needle and (set the bug in range) and turn it on. Slowly move the OBS to make the needle go right or left. See if the plane chases the needle. If so, it is connected.
For approaches, use the LOC/Normal setting as that is the same as "high sensitivity" and will hold tight to a line (but stiill requires the bug to be in range as well).
A little trick once you get this all figured out. If you have a crosswind when tracking the GPS or NAV, keep the bug slightly (again like 5 degrees) off in the direction from which the wind is coming. Seems to be the best way to go in that case...
There is one problem with the 430 sim from Garmin. They stopped supporting it years ago. The nav data is several years old. There have been many GPS approachs added in recent years and others have changed significantly.
But, there is a fix. This web page discribes how to hack the data from the new 650 sim and install it into the 430 sim. Works like a champ. This data is about one year old, but much better than what you will get with the Garmin download.
http://www.vansairforce.com/community/showthread.php?t=76306&highlight=Simulator+database
There are a few ways for an autopilot to be connected to a navigational source:
[ul]Connection to the CDI instrument - the autopilot simply receives a differential voltage from the indicator, when the needle tracks one way (say left) a positive voltage is sent to the A/P, and a negative voltage when the needle tracks the other way (in this case right). When the needle of the CDI is centered, i.e. the plane is on course, then no differential voltage is sent to the A/P. With this method, the pilot simply selects the 'NAV' mode and the A/P attempts to fly the plane to get a zero differential voltage. When the GPS is being displayed on the CDI (the CDI is set to 'GPS' rather than 'V/LOC' mode), the autopilot will attempt to fly the leg being tracked. The sequencing of the GPS flight plan has to be manually adjusted for each leg - that is to say, the pilot has to set the OBS heading for each leg of the flight plan.
GPS Steering - the autopilot is connected to the GPS via a RS232 serial data connection. The GPS is able to tell the A/P to steer left/right or straight, and it is also able to lead turns. For instance, when flying a coupled approach, the GPS is able to 'lead the turns' since it can calculate the cross wind influence of the track of the aircraft. GPSS coupled autopilots have the potential to fly a holding pattern and multiple legs of a approach procedure. Since this is a direct connection from the GPS to the A/P, multiple legs of the flight plan in the GPS can be automatically sequenced.
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The Piper Autocontrol (which is a Piper branded Century autopilot) is usually coupled to the autopilot using the HDG mode connected to the CDI. There are some aftermarket conversions to allow this set up emulate a GPSS steering solution. Icarus Avionics offer a Steering Assistance Module (SAM) - http://www.icarusavionics.com/ - which can provide such an interface. Another method, not currently with the Century A/Ps, is to use an adapter with your EFIS system (assuming some deep pockets) such as the Aspen Avionics EA100 (http://aspenavionics.com/index.php/products/ea100/) which can also provide the GPSS support.
Newer autopilots, such as the S-Tec 55x, have GPSS inputs, their older series 30 and 50 have optional upgrades that allow for GPSS.
Did this help or did I just ramble on?!!!
Andy
My apologies. I seemed to imply that I knew nothing about the 430. I have certainly read the manual and have flown with the 430 now for several hours. I am pretty comfortable with those functions that are useful for VFR flights (my current certification) in addition to the traffic functions coupled with the 330. What I was confused about is how to use it with the autopilot.
I appreciate all the comments, but the comment above confused me a bit. I thought the autopilot was set to NAV/GPS, not HDG.
.....just seeing if you would read my ramble!
Just wondering...Is this normal? :-)
Just wondering...Is this normal? :-)
I do not know what Big Andy is suggesting, but if you have the selector on HDG... the AP will follow the heading bug and any GPS or other NAV source will have NO EFFECT on where the plane wants to go.
As mentioned above, if there is a stiff crosswind, then the plane will also drift away from and end up paralleling the magenta line. "Cheating" the heading bug into the wind will reduce the track offset.
The only time my autopilots "hunts" (does S-turns along the track) instead of tracking solidly is when there's been a rapid temperature drop and condensation has formed inside the plane. (I now have some dehumidification strategies employed to prevent that from happening in the future!) For my setup, the "hunting" behavior is definitely not normal--when working properly, the AP flies straight and level.
I realized that if you don't start out on the magenta line, the CDI starts off being offset. (I'm unsure if it needs to be set along with the HDG bug, but I did as well.) If you are off the magenta line, the autopilot will be given the direction to head for the line and will cross. Once that happens, you be swung back until this all dampens out. Eventually (again, if you are off the magenta), you will end up on the line. The way I was playing with this was ended up in an almost 180 degree turn (reversal of course going back and forth between close airports), yielding a cross track correction back to the line. Once I understood all of this and was nearly on the track when I started, setting the HDG bug and the CDI (still not sure about that) to the direct track worked great.