On January 14, 2003, at 1445 central standard time, an Air Tractor AT-401 agricultural airplane, N1537R, was substantially damaged following a loss of control while maneuvering near Alamo, Texas. The non-instrument rated commercial pilot, who was the sole occupant of the airplane, was seriously injured. The airplane was owned and operated by Moad Aviation, Inc., of Weslaco, Texas, under 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed throughout the area for the aerial application flight for which no flight plan was filed. The local flight originated (approximately 1400) from the Mid Valley Dusters Airport (43TX) near Alamo, Texas. The operator reported that the airplane had been flown on a local aerial application flight during the morning hours and was hangared after completion of the flight. He added that their normal procedures is to top-off the left wing prior to hangaring the airplane. The operator's standard fuel load for local flights was 63 gallons, which normally provides for a 2-hour range. The operator reported to the FAA inspector, who responded to the accident site, that the airplane was in the process of executing a turn to reverse direction, when the airplane stalled and impacted the ground in a nose low attitude. The inspector added that the evidence found at the accident site where consistent with an airplane impacting the ground in a nose low attitude, at a relatively slow airspeed. Examination of the wreckage by the FAA inspector and the operator, revealed that the main wreckage came to rest in an open field in an upright position approximately 75-feet from the initial point of impact. The Pratt & Whitney R-1340 radial engine was found separated from the airframe. The two-blade propeller assembly remained attached to the engine crankshaft. One propeller blade was found bent aft around the engine at about the midspan, while the other blade was slightly bent aft. Both wings sustained structural damage and both fuel cells were compromised during the accident sequence. The inspector added that he arrived at the accident site within an hour after the mishap and there was no evidence of fuel or fuel odors at the accident site. There was no fire. The memory card from the SATLOC system installed in the aircraft was recovered by the FAA inspector for further evaluation. The memory card was analyzed and found not to have any information pertaining to the accident flight. The card was returned to the operator upon completion of the investigation. Several attempts were made by the FAA inspector, as well as the NTSB Investigator-in-Charge to interview the 16,600-hour pilot after his release from the hospital following the accident. The pilot did not have any recollection of the accident or the circumstances prior to the mishap.