PA-34-200T Turbo Seneca II
Flight Crew Private; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 42; Flight Crew Total 2230; Flight Crew Type 156
Situational Awareness; Training / Qualification; Confusion; Distraction; Human-Machine Interface
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Flight Crew Overcame Equipment Problem; Flight Crew Became Reoriented; Flight Crew FLC Overrode Automation
Human Factors; Aircraft
I was vectored for the ILS in IFR conditions; flying on autopilot.  Set my Garmin 530W for the ILS.  The PFD in my aircraft is an Aspen Evolution 1000.  As the ILS signal began to center; I changed the autopilot mode from heading hold to GPS; since the Aspen had the final course clearly shown in the HSI portion.  Airplane immediately turned right.  At the time; I had no idea why my Autopilot went nuts.  I disconnected the AP; hand flew back to the ILS; but the display on the Aspen was completely wrong - the unit was REVERSE SENSING.  I used my backup ILS to continue that approach and broke out at 600'.  A very scary ride because I didn't know what was wrong with my autopilot.  Now that I've figured it out; I think there's a flaw in the logic of the Aspen Evolution 1000. For all flight modes except an ILS; the Aspen autosets the course.  However; for an ILS; the Aspen remembers your LAST manual course setting.  Mine was MONTHS prior and happened to be 130; exactly opposite of the approach that I was attempting.  Rather [than] suggest a course; or leave in the last course you had been flying; Aspen reverts to a course that could be months old and definitely not what you're attempting to fly.  In the soup; this can easily lead to a fatal crash.  Had I not be proficient flying without the autopilot and noticed the deviation immediately; I too could have been a fatality.It seems that the Aspen has all of the necessary information in the box already to auto set the course that could be refined by the pilot once the approach has been set.  To revert to some random prior course is just nuts.  In all IFR flying in every airplane I've ever flown; the only time I don't need to set a course is on an ILS; but with the Aspen Evolution; the only time I MUST set a course is on an ILS.   Failure to remember that fact could kill someone if it hasn't already.
PA34 pilot; using an Aspen Evolution 1000 and Garmin 530; reported being confused when the autopilot turned the wrong way from what he expected while intercepting the ILS. He disconnected the autopilot and hand flew the approach successfully.