View source for Piper PA-23

{{short description|Family of twin engine general aviation aircraft built 1952–1981}}
{{Infobox aircraft
 |name = PA-23 Apache/Aztec
 |image = File:1960PA-23-250.jpg
 |caption = PA-23 Aztec 
 |type = Twin-engined light piston utility
 |manufacturer = [[Piper Aircraft]]
 |designer = <!--only appropriate for single designers, not project leaders-->
 |first_flight = 2 March 1952
 |introduction = 1954
 |retired =
 |status =
 |more_users =
 |produced = 1952–1981
 |number_built = 6,976
 |developed_from =
 |variants =
}}

The '''Piper PA-23''', named '''Apache''' and later '''Aztec''', is an American four- to six-seat twin-engined [[general aviation]] [[light aircraft]], used also in small numbers by the [[United States Navy]] and military forces in other countries. Originally designed as the Twin Stinson in the 1950s by the [[Stinson Aircraft Company]], it was produced as the Apache and a more powerful version, the Aztec, by [[Piper Aircraft]] 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 [[Convair|Consolidated Vultee Aircraft Corporation]].<ref name="Peperell" /> The prototype PA-23 was a four-seat, low-wing, all-metal [[monoplane]] with a [[twin tail]], powered by two 125&nbsp;hp [[Lycoming O-290]]-D piston engines;<ref name="Peperell" /> it first flew on March 2, 1952.<ref name="jawa52p238">{{Harvnb|Bridgman|1952|p=238}}</ref> The aircraft performed poorly, so it was redesigned with a single [[Stabilizer (aircraft)|vertical stabilizer]] and an all-metal rear fuselage and more powerful 150&nbsp;hp [[Lycoming O-320]]-A engines.<ref name="Peperell" />

===Apache===
(ICAO code: PA23)

Two new prototypes of the redesigned aircraft, named '''Apache''', were built in 1953<ref name="Peperell" /> and entered production in 1954; 1,231 Apaches were built. In 1958, the '''Apache 160''' was produced with upgraded 160&nbsp;hp (119&nbsp;kW) engines; 816 were built.{{Citation needed|date=February 2019}}
The Apache 160 was superseded in 1962 by the Aztec-derived 235&nbsp;hp (175&nbsp;kW) '''Apache 235'''.{{Citation needed|date=February 2019}} With a 1962 price of $45,000, the Apache 235 featured the Aztec's engines and swept tail surfaces<ref>{{cite magazine |title=Piper Apache 235 (advertisement) |magazine=[[Flying (magazine)|Flying]] |date=November 1962 |volume=71 |issue= 5 |pages=10–11 |url=https://books.google.com/books?id=S-45uoS-v04C }}</ref> (119 built).

===Aztec===
(ICAO code: PA27)
[[File:PiperU11A149067atPima.JPG|thumb|An ex-United States Navy U-11A on display at the [[Pima Air & Space Museum]]]]

In 1959, Piper produced an upgraded version with 250&nbsp;hp (186&nbsp;kW) [[Lycoming O-540]] engines and a swept vertical tail as the PA-23-250, and named it '''Aztec'''.<ref name="Peperell" /> The first models came in a five-seat configuration. In 1961, a longer-nosed variant, the Aztec B, entered production.<ref name="Peperell" /> 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.

==Variants==
===Apache===
[[File:Piper PA-23 Apache SI.jpg|thumb|PA-23 Apache in National Air and Space Museum]]
[[File:Apache on floats 2000.jpg|thumb|Apache on amphibious floats]]
[[File:Piper PA-23 235 G-ASFF SPK 21.10.65 edited-2.jpg|thumb|PA-23 Apache 235 fitted with the Aztec-style square fin and rudder]]
[[File:Piper-Geronimo.jpg|thumb|An Apache with ''Geronimo'' tail modification]]
[[File:N6795Y PA-23-250 Piper Aztec.jpg|thumb|Piper Aztec C with de-cowled [[Lycoming O-540|Lycoming IO-540]]-C4B5 engines]]
;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<ref name="Peperell" />
;PA-23-150 Apache C
:1956 variant with minor changes<ref name="Peperell" />
;PA-23-150 Apache D
:1957 variant with minor changes<ref name="Peperell" />
;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
;Seguin Geronimo
:Apache with a series of modifications to the engines, nose, and tail<ref>{{cite web|author1=Bill Cox|title=Geronimo! For many light-twin owners, Piper's Apache is about as good as it gets|url=http://www.planeandpilotmag.com/article/geronimo/|website=Plane & Pilot|publisher=Madavor Media|access-date=13 January 2017|date=December 1, 2004}}</ref>

===Aztec===
[[File:Piper PA-23-250 Aztec E, Private JP5624327.jpg|thumb|PA-23 Aztec over [[Maho Beach]], St. Martin]]

;{{visible anchor|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)
;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.
;U-11A
:United States Navy designation formerly UO-1.
;UO-1
:United States Navy designation for PA-23-250 Aztec with additional equipment; 20 delivered, later re-designated U-11A.
;C-26
:[[Brazilian Air Force]] designation of the PA-23-250 Aztec.<ref>{{Cite web |title=Brazilian Military Aircraft Designations |url=https://designation-systems.net/non-us/brazil.html |access-date=2025-03-17 |website=designation-systems.net}}</ref>
;PA-41P Pressurized Aztec
:Pressurized Aztec concept, one built.

==Operators==

===Military operators===
; {{flag|Angola}}<ref>{{harvnb|Fontanellaz|Cooper|Matos|2020|pp=9–10}}</ref>
; {{ARG}}
; {{BOL}}
; {{BRA}}
; {{CMR}}
; {{COL}}
; {{CRI}}
* [[Public Force of Costa Rica]]<ref>{{harvnb|Hagedorn|1993|p=128}}</ref>
; {{CUB}}
* ''Fuezas Aéreas Ejército de Cuba''<ref>{{harvnb|Hagedorn|1993|p=18}}</ref>
; {{ESA}}
;{{GTM}}
*[[Armed Forces of Guatemala|Guatemalan Air Force]]<ref>{{harvnb|Hagedorn|1993|p=55}}</ref>
; {{HND}}
* [[Honduran Air Force]]<ref>{{harvnb|Hagedorn|1993|p=72}}</ref>
; {{HTI}}
* [[Armed Forces of Haiti|Haitian Air Force]]<ref>{{harvnb|Hagedorn|1993|p=134}}</ref>
; {{MDG}}
; {{MEX}}
;{{NIC}}
* [[Nicaraguan Air Force]]<ref>{{harvnb|Hagedorn|1993|p=42}}</ref>
; {{ESP}}
* [[Spanish Air Force]]
** [[Escuadrón 912]]
** [[Escuadrilla de Enlace 905]]
; {{PAR}}
* [[Paraguayan Air Force]]
** [[Grupo Aéreo de Transporte Especial/GATE]]
; {{PNG}}
* Air Operations Element, [[Papua New Guinea Defence Force]] - former operator
; {{UGA}}
; {{USA}}
* [[United States Navy]]
; {{VEN}}
;{{Flagicon|Uruguay}} [[Uruguay]]
;*[[Uruguayan Air Force]]

==Accidents and incidents==
<!-- Note, the vast majority of accidents and incidents are non-notable in Wikipedia's terms and should not be included here. Notable accidents include those involving Wikinotable people or collisions with military or commercial civil airliners.-->
*On 21 March 1964, a Piper PA-23-160 Apache (G-ASHC) crashed on its approach to the Aintree racecourse, near Liverpool, England, 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.<ref>{{cite web|title=ASN Wikibase Occurrence # 66552: Accident Piper PA-23-160 Apache G-ASHC, 21 Mar 1964 |work=Aviation Safety Network |url=http://aviation-safety.net/wikibase/wiki.php?id=66552 |access-date=25 February 2019}}</ref>{{verify source|The wikibase part of Aviation SafetyNetwork is user edited and hence not a RS|date=February 2019}}
*On 8 May 1966, [[Pennsylvania Attorney General]] [[Walter Alessandroni]], his wife, [[Montgomery County, Pennsylvania|Montgomery County]] Republican chairman James E. Staudinger, and pilot Melvin E. Ladin were killed when the Piper Aztec they were traveling to a campaign speech in crashed in the [[Allegheny Mountains]] near [[Somerset, Pennsylvania]].<ref>{{cite news |title=4 Found Dead In Air Crash |url=https://books.google.com/books?id=nSZPAAAAIBAJ&pg=PA2&article_id=5641,4596195&hl=en |access-date=4 November 2025 |work=Toledo Blade |date=May 10, 1966}}</ref>
*On 18 July 1967, Aztec C ''PP-ETT'' was hit by a [[Lockheed T-33]] of the Brazilian Air Force near [[Fortaleza|Mondubim]], Brazil, killing former Brazilian President [[Humberto de Alencar Castelo Branco]].<ref>[http://www.adur-rj.org.br/5com/pop-up/morte_castello.htm The second death of Castello Branco]</ref> 
*On 18 April 1974, Aztec ''G-AYDE'' collided with [[Court Line Flight 95]], a [[BAC One-Eleven]], 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 29 November 1975, retired [[Formula One]] racing driver and [[Embassy Hill]] team owner [[Graham Hill]] was [[Graham Hill plane crash|piloting]] a Piper PA-23-250 Turbo Aztec D, marked as N6645Y,{{efn|Although marked with U.S. registration and carrying matching and unexpired registration documents, the aircraft's U.S. registration had been canceled after it was exported to the Bahamas, and its new owners had not re-registered it.<ref>{{cite report |url=https://assets.publishing.service.gov.uk/media/5422f6a040f0b61342000593/14-1976_N6645Y.pdf |title=Piper PA-23 Turbo Aztec 'D' N6645Y Report on the accident at Arkley Golf Course, Arkley, Hertfordshire, on 29 November 1975 |publisher=Accidents Investigation Branch |date=29 September 1976 |accessdate=25 May 2024|p=8}}</ref>}} from [[Circuit Paul Ricard]], France, to London, United Kingdom.<ref name=Hillreg>{{cite web |url=http://www.aaib.gov.uk/cms_resources.cfm?file=/14-1976%20N6645Y.pdf |title=Aircraft Accident Report 14/76 |publisher=Accidents Investigation Board |date=29 September 1976 |access-date=25 November 2011}}</ref> His passengers were Embassy Hill race driver [[Tony Brise]], team manager Ray Brimble, designer Andy Smallman, and mechanics Terry Richards and Tony Alcock. While on approach to land at [[Elstree Airfield]], [[Hertfordshire]], shortly before 10&nbsp;pm, the aircraft hit trees on a golf course at [[Arkley]], Hertfordshire in thick fog. [[1975 Grand Prix (Bahamas) Ltd Piper PA-23 Aztec crash|The ensuing crash and explosion]] killed everyone on board.<ref name="BBC">[[BBC]], [http://news.bbc.co.uk/onthisday/hi/dates/stories/november/29/newsid_2527000/2527363.stm This day in history-- 1975: Graham Hill killed in air crash.]</ref><ref name="NYTimes2">Graham Hill, 46, Retired Racer, In Fatal Crash Piloting His Plane. [[United Press International|UPI News Service]]. December 1, 1975 (Monday) [https://www.nytimes.com/1975/12/01/archives/graham-hill-46-retired-racer-in-fatal-crash-piloting-his-plane.html New York Times archive]</ref>
*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.<ref>{{cite news|url=https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=41626&key=0|title=NTSB Identification: LAX78FA043|work=[[National Transportation Safety Board]]|access-date=July 27, 2017}}</ref><ref>{{cite web |url=http://www.check-six.com/Crash_Sites/Tallman-N5641Y.htm |title=The Reaper Catches Up . . . In Trabuco Canyon, California April 15, 1978 |publisher=Check-Six.com |access-date=July 8, 2016}}</ref>

==Specifications (PA-23-250F, normally aspirated)==
{{multiple image
 |total_width = 500
 | image1 = Piper PA-23 Apache 3-view line drawing.svg
 | alt1 = 3-view line drawing of the Piper PA-23-150 Apache
 | caption1 = 3-view line drawing of the Piper PA-23-150 Apache
 | image2 = Piper PA-23 Aztech Dreiseitenansicht.svg
 | alt2 = 3-view line drawing of the Piper PA-23-250 Aztec
 | caption2 = 3-view line drawing of the Piper PA-23-250 Aztec
}}

{{Aircraft specs
|ref=Jane's All The World's Aircraft 1976–77<ref name="Janes 76 p348-9">{{harvnb|Taylor|1976|pp=348–349}}</ref>
|prime units?=imp
<!--
        General characteristics
-->
|genhide=

|crew=1
|capacity=5 passengers
|length m=
|length ft=31
|length in=2+3/4
|span m=
|span ft=37
|span in=2+1/2
|height m=
|height ft=10
|height in=4
|wing area sqm=
|wing area sqft=207.56
|aspect ratio=6.8:1
|airfoil=USA 35B (modified)
|empty weight kg=
|empty weight lb=3180
|gross weight kg=
|max takeoff weight lb=5200
|fuel capacity={{convert|140|USgal|impgal L|abbr=on}} usable fuel (normal), optional extra tanks with {{convert|40|USgal|impgal L|abbr=on}}
<!--
        Powerplant
-->
|eng1 number=2
|eng1 name=[[Lycoming IO-540]]-C4B5
|eng1 type=normally aspirated air-cooled [[flat-six]] [[piston engine]]s
|eng1 kw=<!-- prop engines -->
|eng1 hp=250
|prop blade number=2<!-- propeller aircraft -->
|prop name=Hartzell HC-E2YK-2RB constant-speed propellers
|prop dia m=<!-- propeller aircraft -->
|prop dia ft=<!-- propeller aircraft -->
|prop dia in=<!-- propeller aircraft -->

<!--
        Performance
-->
|perfhide=

|max speed kmh=
|max speed mph=215
|max speed kts=
|max speed mach=<!-- supersonic aircraft -->
|cruise speed kmh=<!-- if max speed unknown -->
|cruise speed mph=172<!-- if max speed unknown -->
|cruise speed note=at {{convert|10200|ft|m|abbr=on}} (long-range cruise)
|stall speed mph=68
|stall speed note=(flaps down)
|never exceed speed mph=277
|range km=
|range miles=1519
|range nmi=
|range note=at long-range cruise
|ceiling m=
|ceiling ft=18950
|ceiling note=(absolute ceiling)
|climb rate ms=
|climb rate ftmin=1400
|more performance=*'''Takeoff distance to 50 ft (15 m):''' {{convert|1695|ft|m|abbr=on}}
*'''Landing distance from 50 ft (15 m):''' {{convert|1695|ft|m|abbr=on}}

|avionics=
}}

==See also==
{{aircontent|
|related=
|similar aircraft=
* [[Beagle B.206]]
* [[Beechcraft Baron]]
* [[Beechcraft Travel Air]]
* [[Beechcraft Twin Bonanza]]
* [[Cessna 310]]
* [[Helio Twin Courier]]
* [[Let L-200 Morava]]
* [[Partenavia P.68]]
* [[Piper PA-34 Seneca]]
|lists=
|see also=
}}

==References==

===Notes===
{{notelist}}
<references>
<ref name="Peperell">{{Harvnb|Peperell|Smith|1987|pp=91–104}}</ref>
</references>

===Bibliography===
*{{cite book |last= Bridgman |first=Leonard |title=Jane's All The World's Aircraft 1952–53 |year= 1952 |publisher= Sampson Low, Marston & Company, Ltd. |location= London}}
*{{cite book |last1=Fontanellaz |first1=Adrien |last2=Cooper |first2=Tom |last3=Matos |first3=Jose Augusto |title=War of Intervention in Angola, Volume 3: Angolan and Cuban Air Forces, 1975-1985 |date=2020 |publisher=Helion & Company Publishing |location=Warwick, UK |isbn=978-1-913118-61-7}}
* {{cite book |last=Hagedorn |first=Daniel P. |title=Central American and Caribbean Air Forces |year=1993 |location=Tonbridge, Kent, UK |publisher=Air-Britain (Historians) Ltd |isbn=0-85130-210-6}}
*{{cite book |last1=Peperell |first1=Roger W |last2=Smith |first2=Colin M. | title= Piper Aircraft and their Forerunners | year=1987 |publisher=[[Air-Britain]] | location=Tonbridge, Kent, England | isbn=0-85130-149-5}}
*{{cite book |last=Taylor |first=John W. R. |author-link=John W. R. Taylor |title=Jane's All The World's Aircraft 1976–77  |year= 1976|publisher=Jane's Yearbooks |location= London|isbn=0-354-00538-3  }}

==External links==
{{stack|
{{commons category-inline|Piper PA-23 Apache}}<br>
{{commons category-inline|Piper PA-23-250 Aztec}}
}}
*[http://www.avweb.com/news/features/Used-Aircraft-Guide-Piper-Apache-Aztec-223825-1.html Used Aircraft Guide: Piper Apache-Aztec] by AVweb

{{Piper}}
{{AircraftDesignationNavboxShell
  |1={{USN utility aircraft 1955}}
  |2={{US utility aircraft}}
  |3={{FAB aircraft designations}}
  |4={{Spanish trainer aircraft}}
}}

{{DEFAULTSORT:Piper Pa-23}}
[[Category:Piper aircraft|PA-23]]
[[Category:1950s United States civil utility aircraft]]
[[Category:Low-wing aircraft]]
[[Category:Aircraft first flown in 1952]]
[[Category:Twin piston-engined tractor aircraft]]
[[Category:Aircraft with retractable tricycle landing gear]]