On August 4, 2005, about 0720 Atlantic standard time, a Grumman G-164, N460Y, registered to a private individual and operated by Ponce Crop Dusting Services, as a Title 14 CFR Part 137 agricultural, aerial application flight, stalled during a low altitude maneuver and impacted with terrain near Sabana Grande, Puerto Rico. Visual meteorological conditions prevailed and no flight plan was filed. The commercial-rated pilot received minor injuries. The airplane incurred substantial damage and a private home incurred damage. The flight originated from the Lajas Agriculture Airport, Lajas, Puerto Rico, earlier that day, about 0700. The pilot stated that he departed from the Lajas Agriculture Airport at about 7 am in his Grumman G-164 with a northeast heading. On board the airplane was a load of mircoflex fertilizer, which was to be sprayed on a private farm in Sabana Grande. His first swift run over the farm was successful but as he begun his first procedure turn, he experienced a strong downdraft on the leeward side of the mountain. Unable to recover from the downdraft, the airplane lost altitude and crashed into a backyard of a private home. Neither he nor anyone on the ground was hurt and the private home sustained little damage. He further added the weather was for a visual flight rules operation; with the winds from the north and the temperature was 30 degrees Celsius. The pilot stated there were no mechanical failures or malfunctions to the airplane or any of its systems prior to the accident. The FAA inspector who responded to the accident stated the airplane impacted the ground straight down in a flat attitude and with no forward direction.