The ai-20s drove four-bladed variable pitch reversible props with a diameter of 4. 5 meters (14 feet 9 inches), featuring prominent propeller spinners, and hydraulic actuation for prop pitch. The ai-20s drove four-bladed variable pitch reversible props with a diameter of 4. 5 meters (14 feet 9 inches), featuring prominent propeller spinners, and hydraulic actuation for prop pitch. The ai-20s drove four-bladed variable pitch reversible props with a diameter of 4. 5 meters (14 feet 9 inches), featuring prominent propeller spinners, and hydraulic actuation for prop pitch.