PA-23 Apache/Aztec
Piper PA-23-250 Aztec E, Private JP5624327.jpg
PA-23 Aztec over Maho Beach
Role Twin-engined light piston utility
Manufacturer Piper Aircraft
First flight 2 March 1952
Introduction 1954
Produced 1952–1981
Number built 6,976

The Piper PA-23, named Apache and later Aztec, is an American 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.[1] 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;[1] it first flew on March 2, 1952.[2] The aircraft performed badly, so it was redesigned with a single vertical stabilizer and an all-metal rear fuselage and more powerful 150 hp Lycoming O-320-A engines.[1]


(ICAO code: PA23)

Two new prototypes of the redesigned aircraft, now named Apache, were built in 1953[1] 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160 was produced by upgrading the engines to 160 hp (119 kW); 816 were built.[citation needed] The Apache 160 was superseded in 1962 by the Aztec-derived Apache 235.[citation needed] With a 1962 price of $45,000, the Apache 235 featured the Aztec's 235 hp (175 kW) engines and swept tail surfaces[3] (119 built).


(ICAO code: PA27)

An ex-United States Navy U-11A on display at the Pima Air & Space Museum
An ex-United States Navy U-11A on display at the Pima Air & Space Museum

In 1959, Piper produced an upgraded version with 250 hp (186 kW) Lycoming O-540 engines and a swept vertical tail as the PA-23-250, and named it Aztec.[1] The first models came in a five-seat configuration. In 1961, a longer-nosed variant, the Aztec B, entered production.[1] Later Aztecs were equipped with Lycoming IO-540 fuel-injected engines and six-seat capacity, and remained in production until 1982. Turbocharged versions of the later models could 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 is now there on display.



PA-23 Apache in National Air and Space Museum
PA-23 Apache in National Air and Space Museum
Apache on amphibious floats
Apache on amphibious floats
PA-23 Apache 235 fitted with the Aztec-style square fin and rudder
PA-23 Apache 235 fitted with the Aztec-style square fin and rudder
An Apache with Geronimo tail modification
An Apache with Geronimo tail modification
PA-23 Twin-Stinson
Original designation of the Piper PA-23 Apache
PA-23 Apache
Initial production version, 2047 built (including the Apache E, G and H)
PA-23-150 Apache B
1955 variant with minor changes[1]
PA-23-150 Apache C
1956 variant with minor changes[1]
PA-23-150 Apache D
1957 variant with minor changes[1]
PA-23-160 Apache E
PA-23 powered by two 160 hp O-320-B engines
PA-23-160 Apache G
PA-23 with longer internal cabin and extra window
PA-23-160 Apache H
Apache G with O-320-B2B engines and minor changes
PA-23-235 Apache 235
Apache with five seats and 235 hp O-540 engines, 118 built
PA-23-250 Aztec
Apache G with modified rear fuselage, new fin and rudder and 250hp Lycoming O-540-A1D engines, 4811 built (including subvariants)
Seguin Geronimo
Apache with a series of modifications to the engines, nose, and tail[4]


1960 PA-23-250
1960 PA-23-250
PA-23-250 Aztec B
1962-1964. Aztec with longer nose for a baggage compartment; six seats, new instrument panel and changes to systems.
PA-23-250 Aztec C and Aztec C Turbo
1964-1968. Aztec B with either IO-540-C4B5 engines or turbocharged TIO-540-C1A as an option, also modified engine nacelles and modified landing gear.
PA-23-250 Aztec D and Aztec D Turbo
1969-1970. Aztec C with revised instrument panel and controls.
PA-23-250 Aztec E and Aztec E Turbo
1971-1975. Aztec D with longer pointed nose and a single-piece windshield.
PA-23-250 Aztec F and Aztec F Turbo
1976-1981. Aztec E with improved systems and cambered wingtips and tailplane tip extensions.
United States Navy designation formerly UO-1.
United States Navy designation for PA-23-250 Aztec with additional equipment; 20 delivered, later re-designated U-11A.
PA-41P Pressurized Aztec
Pressurized Aztec concept, one built.


Military operators

 Costa Rica
 El Salvador
 Papua New Guinea
 United States
Uruguay Uruguay

Specifications (PA-23-250F, normally aspirated)

3-view line drawing of the Piper PA-23 Aztec

Data from Jane's All The World's Aircraft 1976–77[12]

General characteristics


Accidents and incidents

See also

Aircraft of comparable role, configuration, and era



  1. ^ Although marked with a United States registration and carrying the appropriate registration documentation the aircraft had been cancelled from the American register in 1974; the new owners had not re-registered the aircraft so was unregistered and stateless at the time of the accident
  1. ^ a b c d e f g h i Peperell & Smith 1987, pp. 91–104
  2. ^ Bridgman 1952, p. 238
  3. ^ "Piper Apache 235 (advertisement)". Flying. Vol. 71, no. 5. November 1962. pp. 10–11.
  4. ^ Bill Cox (December 1, 2004). "Geronimo! For many light-twin owners, Piper's Apache is about as good as it gets". Plane & Pilot. Madavor Media. Retrieved 13 January 2017.
  5. ^ Fontanellaz, Cooper & Matos 2020, pp. 9–10
  6. ^ Hagedorn 1993, p. 128
  7. ^ Hagedorn 1993, p. 18
  8. ^ Hagedorn 1993, p. 55
  9. ^ Hagedorn 1993, p. 72
  10. ^ Hagedorn 1993, p. 134
  11. ^ Hagedorn 1993, p. 42
  12. ^ Taylor 1976, pp. 348–349
  13. ^ "ASN Wikibase Occurrence # 66552: Accident Piper PA-23-160 Apache G-ASHC, 21 Mar 1964". Aviation Safety Network. Retrieved 25 February 2019.
  14. ^ The second death of Castello Branco
  15. ^ "Aircraft Accident Report 14/76" (PDF). Accidents Investigation Board. 29 September 1976. Retrieved 25 November 2011.
  16. ^ BBC, This day in history-- 1975: Graham Hill killed in air crash.
  17. ^ Graham Hill, 46, Retired Racer, In Fatal Crash Piloting His Plane. UPI News Service. December 1, 1975 (Monday) New York Times archive
  18. ^ "NTSB Identification: LAX78FA043". National Transportation Safety Board. Retrieved July 27, 2017.
  19. ^ "The Reaper Catches Up . . . In Trabuco Canyon, California April 15, 1978". Retrieved July 8, 2016.


Media related to Piper PA-23 Apache at Wikimedia Commons
Media related to Piper PA-23-250 Aztec at Wikimedia Commons

United States tri-service utility aircraft designations post-1962