DFC90 Flight Test

Today I took the plane up for 2.6 hours to do some flight testing of the new autopilot.  This autopilot is capable of many things; however here is the list of things I tested during this flight:

·         Take Off Settings – AP set armed but not active

·         Flight Director on and Vertical Speed set to 1000 FPM climb

·         Turn to assigned heading (070), switch to Indicated Air Speed Mode (IAS) (115 knots Indicated)

·         Straight and Level – Put aircraft into an unusual attitude and push S&L Button

·         Underspeed Protection  

§  Stall aircraft COUPLED – “Speed protection active” should engage

§  Stall aircraft UNCOUPLED – “Caution underspeed” should be announced

·         Overspeed Protection

§  Dive aircraft COUPLED - “Speed protection active” should engage

§  Dive aircraft UNCOUPLED – “Caution overspeed” ” should be announced

·         Test Bank Angle

§  Exceed bank limit – “Caution, excessive bank” should be announced

·         Course Intercept – Set up a 90 degree intercept (V-Airway).    Fly heading mode and GPSS steering should allow a smooth intercept of the navigation course line

·         Test automatic Baro Setting – Fly level AP COUPLED and change Baro settings.  Should automatically adjust altitude with pressure changes

·         IAS - Set 88 knots for best glide and cut power.  Aircraft should set up for 88 knots and stay there

·         RNAV (GPS) Approach with published miss and hold.

·         ILS Approach, both coupled and by hand with flight director.

Before I could even start my testing, the weather was quickly deteriorating.  At the time of take-off, Dothan’s weather was MVFR, 5-mile visibility with mist and a broken layer at 1800’, overcast at 11,000.  I departed in the rain and headed to the south east, where several airports were still showing VFR.  To the west a front was moving in and bringing with it lots of rain.  Just south of the field, the weather was VFR, so I did some maneuver work to test the S&L button and envelope protection.  All worked as advertised and the S&L button is a really amazing feature!  The one thing that didn’t work was the uncoupled envelope protection.  I tried this several times and even confirmed that my software was update, so it must be a setting that needs to be turned on.  Next I set up a flight plan and did some 90 degree interception work.  As advertised, the DFC90 interception and turned onto the course with no issues. 

After about an hour of flying, the DFC90 started to have some issues.  After two successful attempts to intercept a course, the heading feature stopped working or at best barely worked.  The PFD started to show a yellow message stating SERVO LIMIT and the plane would barely begin turning.  I disconnected the AP and tried to re-engage, but got similar results.  On a couple of attempts, it would slowly begin to turn and then completely overshoot the heading and just keep on turning.  I decided to change it up and try something else to see what it would do.  I changed my GPS to a close by airport and programmed in an RNAV approach.  The AP did as commanded and all seemed to be fine.  I’m not sure if something wasn’t programmed correctly or what, but from that point on, everything worked great.

Since the weather was quickly deteriorating, I called Cairns Approach and filed IFR and asked for the RNAV (GPS18) approach into Dothan with an initial fix of IKIQU.  This approach was done completely coupled and the DFC90 executed it perfectly!  I even tried the IAS mode set at 100 knots and it all worked great.  The approach was picture perfect with a breakout at minimums.  AWESOME!  After going missed, I flew to the hold and hoped that maybe my non-WAAS G430s would now be able to fly the hold, but unfortunately that is not the case.  I entered the hold in a teardrop fashion and flew the hold using the heading bug. 

After a few turns, I asked for vectors to the ILS from the east.  This approach went very well also.  I allowed the DFC90 to fly it coupled and it intercepted the final approach coarse perfectly, as well as the glide slope and tracked it all the way down until we broke out of the clouds at 500’ AGL.  The next approach was vectors back to the RNAV (GPS18) again with similar results.  The final approach was for vectors from the west to the ILS RW14 and I hand flew this approach using only the Flight Director for guidance.  This approach didn’t go as well, since it seemed like the FD was slow to react, so I just followed the needles to get me though the clouds.  I’m not sure if it was the FD or if maybe I didn’t have something set up correctly, so I can’t say if the FD was having issues or not.  I guess I’ll have to go out and try that one again. 

Overall, I am extremely happy with the performance of the new DFC90.  I did have a few glitches, but I’m not sure that it is anything to worry about at this time.  I really like the preciseness of the unit as well as the envelope protection.  It just provides my Cirrus with even more safety features that make me love my Cirrus all that much more.