According to the pilot, he had just leveled off the motor glider after an initial climb when the left canopy latch loosened and the canopy raised up about 2 inches. With wind blowing into the cockpit area, the pilot returned to the departure airport and made a straight-in approach, landing left of runway centerline. The motor glider subsequently veered to the left during the landing rollout and groundlooped, striking runway signage and lighting, and substantially damaging the composite left wing. According to a Federal Aviation Administration inspector, there were no preaccident mechanical anomalies noted with the motor glider, and the canopy latch system functioned normally. The pilot, who reported 39 hours in make and model, also noted "vision problems with airflow into cockpit" during the approach and landing. Winds, recorded at the airport about the time of the accident, were variable, between 3 and 6 knots.