for more than 100 aircraft each year. The study also showed that most of the concerns expressed by agricultural aircraft operators were addressed by the Ag Cat C model. The Grumman American subsidiary, which also owned the Grumman Gulfstream design series, was sold to American Jet Industries in 1978. From initial production through 1981, Schweizer built 2,455 aircraft under contract. In 1981 Schweizer bought the rights to the design and continued production under the name Schweizer Ag Cat. Schweizer sold the design to Ag Cat Corp. of Malden, Missouri in 1995. Five model G-164B aircraft were produced and registered before Ag Cat Corp. entered bankruptcy. One additional aircraft, a G-164BT500, is listed in the FAA registry as having been produced by Ag-Cat Corp., but no tail number was issued. This may have been an upgrade to an existing airframe. In February 2001, the design was sold to Allied Ag Cat Productions Inc. of Walnut Ridge, Arkansas. Allied Ag Cat is not producing new aircraft, although a related company operates a large fleet of Ag-Cats. The basic airframe incorporates many safety innovations, including a pressurized cockpit to keep pesticides out, air conditioning, and a fuselage structure that is designed to progressively collapse in the event of a collision. Lippert and Koch were recognized for their innovation in agricultural aircraft, being awarded the Puffer Award by Delta Air Lines in 1974. Floats were approved for the aircraft in the early 1990s in Australia. Variants Ag Cat The basic model Ag Cat was certified with four different engines - the 220-225 hp (164-168 kW) Continental Motors radial engine, the 240 hp (179 kW) Gulf Coast W-670-240 radial engine, the 245 hp (183 kW) Jacobs L-4M or L-4MB radial engine, and the 275-300 hp (205-224 kW) Jacobs R-755 radial engine. A total of 400 of this model was produced. Super Ag Cat A/450 The G-164A became the main model starting with serial number 401. This model featured a 450 hp (335 kW) Pratt & Whitney R-985 radial engine along with a higher gross weight, increased fuel capacity, larger diameter wheels, and improved brakes. Super Ag Cat A/600 The A/600 incorporated the same improvements embodied in the A/400, but was powered by a Pratt & Whitney R-1340 radial engine of 600 hp (450 kW). Super Ag Cat B/450 The B/450 improved on the "A" model by increasing the wingspan from 35 ft 11 in (10.95