Bonanza 33
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 35; Flight Crew Total 5000; Flight Crew Type 4500
Workload; Distraction; Situational Awareness; Time Pressure; Troubleshooting
Aircraft Equipment Problem Critical; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overrode Automation; Flight Crew Regained Aircraft Control; Flight Crew Took Evasive Action; Flight Crew Overcame Equipment Problem
Aircraft
On short final to a visual landing at ZZZ; the autopilot (which was turned off); pushed the nose towards the ground. I was surprised. I pushed and held the autopilot disconnect; recovered and landed.I was familiar with the ESP (Electronic Stability & Protection) feature on my recently installed Garmin GFC 500 autopilot in theory; but seeing it in practice was scary.Landing speeds for my airplane are 64 to 70 knots depending on weight per the POH. I was light; winds were light; and I intended on landing at 68 knots. The GFC 500 ESP pushes the nose down below 70 knots. Note that a V Tail bonanza with the exact same flight characteristics has a GFC 500 ESP speed of 65 knots; which is better.This is a hazard that needs a software modification to correct.
BE-33 pilot reported a recently installed Garmin GFC 500 autopilot pushed the aircraft nose over un-commanded. The pilot recovered by continuously pushing the disconnect switch. The pilot believes this should be addressed by the manufacturer.