MSR Fail message on PFD
This is an indication that is generated by the DFC90 autopilot computer. Essentially this fault means the DFC90 is unable to read/write to an internal memory component. This will not affect any of the operation of the autopilot, but will cause the aural alerting to cease. The unit will need to come back to Avidyne…
DFC90/100 Servo Start Up Voltages - Cirrus and Piper
This should be tested using a variable DC power supply, connected as displayed in the image below: Once connected, begin at 0VDC and slowly increase voltage until the servo begins to respond. That will be your "start-up voltage." DFC90 Servo Start Up Voltages Roll Servo should be less than 3VDC Pitch Servo…
DFC90 Wings Level
Straight and Level - Pressing the "Straight and Level" button on the autopilot will result in a zero bank, +2 degree pitch angle attitude. It is not an altitude hold or a zero vertical speed mode, nor does it hold a heading. Depending on the power setting and aircraft configuration, this could produce a climb, stea…
DFC90 Autopilot Disconnects
The DFC-90 requires Aircraft Power to be supplied to "A/P Disconnect" P1-17 and "Trim Interrupt " P2-14. If either input is missing the Autopilot will Disengage. The most common cause of DFC-90 problems is the connector mating into the old S-Tec 55x Tray. Insure that the unit is securely seated into the rack. …
Servo Limit Message on PFD
Generally this means the DFC90 is seeing a problem with the roll servo. The roll servo is the only one that will trigger a "Servo Limit" message. Recommend having an avionics shop perform the Start Up Voltage tests on the roll servo.
DFC90 Self Test
The DFC 90 uses 4 criteria to set the self-test failure bit. 1. Servo Fail - Compares expected current and voltage draws of the servos to the actual current and voltage draws of the servos. If the measured value is out of tolerance, the servo fail bit is asserted. (The measured servo readings must be within 500…
DFC90 Audio Fail message
The DFC90 "Audio Fail" message requires the Avidyne Dealer to RMA the unit. Please use the 'Find a Dealer' link at the top of Avidyne.com to find your closest Avidyne Dealer. The card has become "corrupted" due to the fact that it writes information and deletes old information. This can only be done a certain numb…
DFC90 Self Test Fail
If you get a self test fail annunciation please have the following completed by your local Avidyne dealer. 1. Verify Autopilot is properly seated in its tray. 2. Verify no Autopilot external devices has failed (i.e. trim/servo motors, turn coordinator, autopilot disconnect, trim/servo motor, etc.) If the abo…
DFC90 Servo Logic SR22 with Pitch/Pitch-Trim
The following is a theory of operation of the pitch/pitch-trim system. The attached drawing will help, and it is advised to opening the drawings while reading through the paragraphs below. The lines highlighted in blue are grounds, and the lines highlighted in yellow are bus voltage (28V). Pitch Down Trim Relay …
DFC90 Trim Tab Test
* With the aircraft in straight and level flight (hand flying) using the hat switch, roll the trim full left. Let go of the stick and count how long the aircraft takes to roll to the 45dg mark on the PFD (typically 3-5 secs). * Conduct the same test to the right. With the aircraft straight and level using the hat…
