The Piper PA-23, named Apache and later Aztec, is a four-to-six-seat twin-engined light aircraft aimed at the general aviation market. The United States Navy and military forces in other countries also used it in small numbers. Originally designed in the 1950s by the Stinson Aircraft Company, Piper Aircraft manufactured the Apache and a more powerful version, the Aztec, in the United States from the 1950s to the 1980s.
Design and development
The PA-23 was the first twin-engined 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-seat low-wing all-metal monoplane with a twin tail, powered by two 125 hp Lycoming O-290-D piston engines; it first flew on March 2, 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.
Apache
Two new prototypes of the redesigned 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 ; 816 were built. The Apache 160 was superseded in 1962 by the Aztec-derived Apache 235. With a 1962 price of $45,000, the Apache 235 featured the Aztec's 235 hp engines and swept tail surfaces.
Aztec
The same year, Piper produced an upgraded version with 250 hp Lycoming O-540 engines and a swept vertical tail as the PA-23-250, and named it Aztec. The first models came in a five-seat configuration in 1959. In 1961 a longer nosed variant, the Aztec B, entered production. Later Aztecs were equipped with IO-540 fuel-injected engines and six-seat capacity, and remained in production until 1982. There were also turbocharged versions of the later models, which could fly at higher altitude. 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 condition that it never be flown again. It is now there on display.
Variants
Apache
;PA-23 Twin-Stinson ;PA-23 Apache ;PA-23-150 Apache B ;PA-23-150 Apache C ;PA-23-150 Apache D ;PA-23-160 Apache E ;PA-23-160 Apache G ;PA-23-160 Apache H ;PA-23-235 Apache 235 ;PA-23-250 Aztec ;Seguin Geronimo
Aztec
;PA-23-250 Aztec B ;PA-23-250 Aztec C and Aztec C Turbo ;PA-23-250 Aztec D and Aztec D Turbo ;PA-23-250 Aztec E and Aztec E Turbo ;PA-23-250 Aztec F and Aztec F Turbo ;U-11A ;UO-1 ;PA-41P Pressurized Aztec
On 21 March 1964, a Piper PA-23-160 Apache crashed on its approach to Aintree racecourse, near Liverpool, killing all 5 on board. The flight had taken off from Luton Airport and included broadcaster Nancy Spain, who was covering the Grand National, and her friend Joan Werner Laurie, who was learning to fly. The CAA accident report stated that passenger interference could not be ruled out as a cause of the accident.
On 18 April 1974, Aztec G-AYDE was involved in a ground collision with BAC One-Eleven G-AXMJ at London Luton Airport after the pilot of the Aztec entered the active runway without clearance. He was killed and his passenger was injured. All 91 people on board the One-Eleven successfully evacuated after the takeoff was aborted.
On 15 April 1978, Hollywood stunt flyer Frank Tallman was ferrying a Piper Aztec from Santa Monica Airport, California, to Phoenix, Arizona under visual flight rules when he continued the flight into deteriorating weather, a lowering ceiling and rain. He struck the side of Santiago Peak in the Santa Ana Mountains near Trabuco Canyon at cruise altitude, dying in the ensuing crash.
