A/P GPS question

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N182BF

Filing Flight Plan
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Oct 22, 2011
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Rhode Island
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Gary
I fly 2001 T182T with factory installed KAP 140 auto pilot with Alt.Hold and KLN 94 GPS is it posable to have the auto pilot follow the GPS course without input from the pilot when a direction change is needed ( like following an airway on a IFR flight plan) instead of manually turning the HSI or heading bug course to change course
 
Check your flight manual supplement. If you don't have the -0102 version of the KLN94 I don't think you get roll steering, so you have to set the course properly or use the heading bug if you don't have an HSI to tell the autopilot what your general course is before it transitions to using left-right signals from the CDI.

You can also flight test it by programming in a flight plan with some significant changes in direction at waypoints, get established properly on one leg in NAV mode, and then don't touch anything. If the autopilot smoothly makes the direction changes as it reaches a waypoint, you've got roll steering. If it doesn't, or the GPS "alerts" you to change the CDI/HSI course, you probably don't have roll steering. I'm pretty sure that only the -0102 version of KLN94 puts out that signal.
 
Thanks Tim, I do have a section on roll steering I'll look into it for sure I fly IFR cross country flights often if I have that option it sure would help
 
If this is an aftermarket (didn't come from the factory that way) it my not have been hooked up. If you find that you don't have it, you should ask your avionics guy to tell you what's missing. You may just not have the right "rev" of the KLN-94.
 
What Tim said plus if you do have GPSS I think you will still have to manually set the HSI to match the course just to get agreement. It will not affect the actual tracking of the GPS course
 
The GPS,Autopilot and the HSI are all King and were delivered with the airplane when it was new
 
Gary, I do not know anything about that GPS. As Tim was saying you will just have to check it out. Do a flight and program a short trip with a 30 deg or so course change in the middle of the trip and see if the AP follows the GPS or follows the needle on the HSI. Put it in NAV mode and make sure it is coupled and that NAV has captured the selected course. Then when you get to your way point with the 30 deg course change the AP should make the turn and follow the new course if you have GPSS even though the needle on the HSI will start to swing off center. If the AP follows the needle movement then no GPSS. It may be no more than hooking up the GPSS. Any descent avionics shop can determine that. Hope this helps.

Ronnie
 
The KLN94 has an analog roll steering output. The analog roll steering from the KLN94 can interface to a KFC225 or KAP140, but the performance is marginal at best. With the KAP140, the maximum rate of turn is limited to 2.7 degrees per second, or 90% of standard rate. The KLN94 is not compatible with any of the aftermarket GPSS units as it does not support the ARINC 429 digital interface that is required by these units.
 
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