Small Aircraft
Flight Crew Private; Flight Crew Instrument
Flight Crew Last 90 Days 23; Flight Crew Total 2300; Flight Crew Type 690
Communication Breakdown; Situational Awareness
Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
Human Factors; Procedure
I was approaching L52 from the north/west to enter a left downwind for Runway 29. As I was crossing the shoreline at 1;000 AGL (one mile out) and decelerating; my passenger and I spotted two powered gliders crossing the departure end of 29 at approximately 900 feet AGL.They seemed to be transitioning from the southern part of the dunes to the norther part of the dunes through the upwind part of the traffic pattern. I veered the aircraft slightly more to the south to avoid them when I spotted another powered glider transitioning from the south to the north by intersection the downwind leg of the left pattern to 29. He was coming directly toward my aircraft in the opposite direction of traffic pattern. I then had to veer slightly to the left (north/east) to avoid that vehicle. I then landed without incident on 29.When parked at transient space we witnessed another powered glider takeoff from the tarmac and join the other gliders.  They continued to overfly the airport at pattern altitude and not seem to adhere by any observable pattern.
GA pilot reported an NMAC with powered gliders during approach to L52 non-towered airport. Reporter stated the gliders were not following pattern procedures.