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rkahmann
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| Joined: | Sun Feb 12th, 2006 |
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Posted: Tue Apr 18th, 2006 02:24 pm |
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| What is the best technique for lowering flaps when using the autopilot? If you lower flaps when the airspeed is too high I will get an audible warning "trim in motion" followed by inactivation of the autopilot. I think this happens because of the force put on the autopilot servos by the application of the flaps. Is the best technique to pull the throttle way back to lower the airspeed followed by application of the flaps?
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rkaplan
Administrator
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Posted: Tue Apr 18th, 2006 02:32 pm |
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What airplane are you flying?
What is your first notch of flaps maximum extension speed?
What speed are you attempting this procedure at?
Yes, generally it is a good idea to first reduce speed with power as you suggest but the specifics depend on the aircraft.
____________________
Richard Kaplan, CFII
rkaplan@flyimc.com
http://www.flyimc.com
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rkahmann
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Posted: Tue Apr 18th, 2006 05:15 pm |
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I fly a 2005 T182T. Normally fly the approach at 90 kts with 10 deg of flaps. The uncoupling of the autopilot occurs when going from no flaps to 10 degrees.
The uncoupling occurs when you apply the flaps, the nose raises up and the yoke needs to be pushed forward to counter this force. The forward pressure appears to be too much for the autopilot servos.
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rkaplan
Administrator
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Posted: Wed Apr 19th, 2006 02:14 am |
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What airspeed are you at when you extend the flaps?
That sounds as if there may be a maintenance-related issue with your autopilot.
____________________
Richard Kaplan, CFII
rkaplan@flyimc.com
http://www.flyimc.com
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MTrescott
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| Joined: | Fri Apr 28th, 2006 |
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Posted: Fri Apr 28th, 2006 07:28 am |
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That's a very common behavior on the C182, particularly if you extend the flaps anywhere near the 140 knots (as I recall) max speed for the first 10 degrees of flaps. I've been told (but never confirmed) that it kicks off the autopilot because it exceeds the 1.6G limitation of the KAP 140 autopilot. I had a comment about this in my G1000 Glass Cockpit Handbook but pulled it out at the last minute as I hadn't confirmed it (though the 1.6G limitation is in the specs so it seemed like a credible explanation).
Max Trescott
http://www.G1000Book.com
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Snafu
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Posted: Thu Oct 26th, 2006 09:45 pm |
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I fly a 2001 T182T with the same autopilot. Putting out the 10 degrees of approach flaps will always yield the "trim in motion" announcement. However, it never kicks off the autopilot as a result. I generally am slowed to 120 or less before putting out the first notch of flaps, but have done so up to flap-limiting speed of 140 kts with no decoupling.
I believe that the KAP 140 has a number of SBs pertaining both the system (tensions primarily) and the computer (gain). These are related to the "wing walking" behavior seen on some G1000 installations; I wonder if your decoupling might be resolved by some or all of these SBs.
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