On May 9, 2010, about 1545 central daylight time, a Gross Cozy III experimental amateur built airplane, N144TJ, was substantially damaged during an off-airport forced landing at Pine Bluff, Arkansas. The solo pilot sustained minor injuries and five persons on the ground sustained minor injuries. The airplane was owned and operated by a private individual. Visual meteorological conditions (VMC) prevailed at the time of the accident and a flight plan had not been filed for the 14 Code of Federal Regulations Part 91 personal flight. The airplane had departed Monroe Regional Airport (MLU), Monroe, Louisiana, about 1510, and was enroute to Rochester International Airport (RST), Rochester, Minnesota. The airplane was in cruise flight at 4,500 feet mean sea level (MSL) when the cockpit canopy suddenly opened to about a 90 degree up position. According to the pilot his headset and several other loose items in the cockpit immediately departed the airplane and debris struck and damaged the pusher propeller on the rear of the airplane. The pilot subsequently reported a “large vibration” in the engine. With the engine producing partial power, the pilot headed for the nearest airport about 9 miles away and began an emergency descent. Approximately four miles from the airport the engine experienced a total loss of power and the pilot executed a forced landing on a busy five lane road in the city limits. After missing several vehicles, the airplane struck and damaged the rear of an automobile. The airplane then struck several sign posts and came to rest in a ditch on the side of the road. The airplane was equipped with a right side hinged canopy which functioned as the front windshield, side windows, cabin roof, and was the only access to and from the cockpit. A primary latch lever mounted on the cockpit side wall operated front and rear hooks which engaged two latch studs installed on the lower left edge of the canopy. A spring steel safety catch mounted at the bottom of the primary latch lever would prevent the latch from opening when a latch pin at the bottom of the lever was properly engaged. In the event the primary latch inadvertently opened, a secondary latch system was designed to catch the partially open canopy and prevent the canopy from going to the full open position. The secondary latch system had a spring steel hook installed on the left side of the canopy which engaged a corresponding latch stud installed on the cockpit side wall. An examination of the canopy primary latch system did not disclose any anomalies. An examination of the secondary latch system showed an overstress fracture of the spring steel hook which had separated. The separated portion was found inside the cockpit. Additionally, the engine’s propeller damage was consistent with debris, from the cockpit, striking the propeller when the canopy opened in-flight. During the accident, the airplane’s left canard and wing were substantially damaged. The engine also appeared to have partially separated from its mount.