On September 27, 2001, at approximately 0900 mountain daylight time, a Grumman-Schweizer G-164A, N9925, was substantially damaged when it impacted terrain while maneuvering during an aerial application pass near Parowan, Utah. The commercial pilot, the sole occupant in the airplane, was not injured. The airplane was being operated by Parowan Crop Dusting Services, Inc., Parowan, Utah, under Title 14 CFR Part 137. Visual meteorological conditions prevailed for the local aerial application flight that originated approximately 30 minutes before the accident. The pilot said that he completed an application pass, and turned his head to look for his flagman. He said there was rising terrain in front of him, and he immediately applied full power. The airplane began losing airspeed, and he was unable to increase the climb rate. The airplane impacted the ground in a rough ravine. The left wing spar was bent up and the fuselage was wrinkled. The calculated density altitude was 9,736 feet.