An automatic collective pitch reducer lowered the collective pitch in the event of an engine failure. YH-41A Ten CH-1Bs purchased by the United States Army for evaluation against possible future production contract.[5] CH-1C UH-41A 15 CH-1C aircraft purchased by the United States Government for its Military Assistance Program (MAP) to foreign countries. CH-4 Cessna's entry for the U.S. Army's Light Observation Helicopter program, it was a CH-1C powered by an Allison Model 250 engine mounted behind the rear passenger seat.