Had an incident yesterday when I engaged the AP GNSS/VS mode the AC immediately rolled into a right turn despite already being on course (AC over the magenta line). I was climbing through 5,000 for the altitude bug of 6,500 on a course of 184 with a BTW of 184 and xtrk error of 0.08 nm. The only unusual part was a heading of 204 to correct for a 15-25 knot 90 deg crosswind. After a 75 deg course change I disconnected the AP and returned to on-course. I tried using the HDG/VS mode with the HDG vector matching the magenta course line and got the same right turn as soon as it engaged. I let the AP make most of a 360 deg turn to see what it would do and disconnected the AP when the bank angle got to 40 degrees with 7 deg down angle (PA=5100, Alt Bug = 6500, VS Bug=800, Speed Bug=78, IAS=112, VS=-1,100 fpm). After returning on-course at 6,500 I turned the AP off, then on and selected HDG/ALT mode and the AP appeared to operate as it should. I had flown the reciprocal route a couple of hours earlier in GNSS AP mode and had no issues with track following or Alt Bug decent (and 90 deg Xwinds of 25-35 knots). The only numbers of note in the flight data are the AP Roll Steps went from a fairly steady -26 to 0, AP Pitch Steps from 22 to 0 after I powered the AP off, then on. I have not really had any issues with the AP / IFD-540 and flying coupled RNAV GPS approaches.
Any ideas on why the AP wanted to turn into the wind when already on-course?
John Salak
RV-12 N896HS
Any ideas on why the AP wanted to turn into the wind when already on-course?
John Salak
RV-12 N896HS