Piper PA-23 - Design and Development

Design and Development

The PA-23 was the first twin-engine Piper aircraft and was developed from a proposed "Twin Stinson" design, inherited when Piper bought the Stinson Division of the Consolidated Vultee Aircraft Corporation. The prototype PA-23 was a four-seater low-wing all-metal monoplane with a twin tail, powered by two 125 hp Lycoming O-290-D piston engines; it first flew on 2 March 1952. The aircraft performed badly and it was redesigned with a single vertical stabilizer and an all-metal rear fuselage and more powerful 150 hp Lycoming O-320-A engines. Two new prototypes of the re-designed aircraft, now named Apache, were built in 1953 and entered production in 1954; 1,231 were built. In 1958 the Apache 160 was produced by upgrading the engines to 160 hp (119 kW); 816 were built before being superseded in 1962 by the Apache 235, which was a derivative of the Aztec, fitted with 235 hp (175 kW) versions of the engines used on the Aztec and swept tail surfaces (119 built).

In 1958 an upgraded version with 250 hp (186 kW) Lycoming O-540 engines and a swept vertical tail was produced as the PA-23-250 and was named Aztec. These first models came in a five-seat configuration which became available in 1959. In 1961 a longer nosed variant, the Aztec B, entered production. The later models of the Aztec were equipped with IO-540 fuel-injected engines and six-seat capacity, and continued in production until 1982. There were also turbocharged versions of the later models, which were able to fly at higher altitudes.

The United States Navy acquired 20 Aztecs, designating them UO-1, which changed to U-11A when unified designations were adopted in 1962.

In 1974, Piper produced a single experimental PA-41P Pressurized Aztec concept. This concept was short-lived, however, as the aspects of the Aztec that made it so popular for its spacious interior and ability to haul large loads did not lend themselves well to supporting the sealed pressure vessel required for a pressurized aircraft. The project was scrapped, and the one pressurized Aztec produced, N9941P, was donated to Mississippi State University, where it was used for testing purposes. In 2000, N9941P was donated to the Piper Aviation Museum in Lock Haven, Pennsylvania, on the condition that it never be flown again. It now sits there on display.