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Piper PA-23
Piper PA-23
Piper PA-23
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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.

Key Information

Design and development

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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 poorly, 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]

Apache

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(ICAO code: PA23)

Two new prototypes of the redesigned aircraft, named Apache, were built in 1953[1] and entered production in 1954; 1,231 Apaches were built. In 1958, the Apache 160 was produced with upgraded 160 hp (119 kW) engines; 816 were built.[citation needed] The Apache 160 was superseded in 1962 by the Aztec-derived 235 hp (175 kW) Apache 235.[citation needed] With a 1962 price of $45,000, the Apache 235 featured the Aztec's engines and swept tail surfaces[3] (119 built).

Aztec

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(ICAO code: PA27)

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.

Variants

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Apache

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PA-23 Apache in National Air and Space Museum
Apache on amphibious floats
PA-23 Apache 235 fitted with the Aztec-style square fin and rudder
An Apache with Geronimo tail modification
Piper Aztec C with de-cowled 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[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
Seguin Geronimo
Apache with a series of modifications to the engines, nose, and tail[4]

Aztec

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PA-23 Aztec over Maho Beach, St. Martin
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.[5]
PA-41P Pressurized Aztec
Pressurized Aztec concept, one built.

Operators

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Military operators

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Angola[6]
 Argentina
 Bolivia
 Brazil
 Cameroon
 Colombia
 Costa Rica
 Cuba
  • Fuezas Aéreas Ejército de Cuba[8]
 El Salvador
 Guatemala
 Honduras
 Haiti
 Madagascar
 Mexico
 Nicaragua
 Spain
 Paraguay
 Papua New Guinea
 Uganda
 United States
 Venezuela
Uruguay Uruguay

Accidents and incidents

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

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3-view line drawing of the Piper PA-23-150 Apache
3-view line drawing of the Piper PA-23-150 Apache
3-view line drawing of the Piper PA-23-250 Aztec
3-view line drawing of the Piper PA-23-250 Aztec

Data from Jane's All The World's Aircraft 1976–77[22]

General characteristics

  • Crew: 1
  • Capacity: 5 passengers
  • Length: 31 ft 2+3⁄4 in (9.519 m)
  • Wingspan: 37 ft 2+1⁄2 in (11.341 m)
  • Height: 10 ft 4 in (3.15 m)
  • Wing area: 207.56 sq ft (19.283 m2)
  • Aspect ratio: 6.8:1
  • Airfoil: USA 35B (modified)
  • Empty weight: 3,180 lb (1,442 kg)
  • Max takeoff weight: 5,200 lb (2,359 kg)
  • Fuel capacity: 140 US gal (120 imp gal; 530 L) usable fuel (normal), optional extra tanks with 40 US gal (33 imp gal; 150 L)
  • Powerplant: 2 × Lycoming IO-540-C4B5 normally aspirated air-cooled flat-six piston engines, 250 hp (190 kW) each
  • Propellers: 2-bladed Hartzell HC-E2YK-2RB constant-speed propellers

Performance

  • Maximum speed: 215 mph (346 km/h, 187 kn)
  • Cruise speed: 172 mph (277 km/h, 149 kn) at 10,200 ft (3,100 m) (long-range cruise)
  • Stall speed: 68 mph (109 km/h, 59 kn) (flaps down)
  • Never exceed speed: 277 mph (446 km/h, 241 kn)
  • Range: 1,519 mi (2,445 km, 1,320 nmi) at long-range cruise
  • Service ceiling: 18,950 ft (5,780 m) (absolute ceiling)
  • Rate of climb: 1,400 ft/min (7.1 m/s)
  • Takeoff distance to 50 ft (15 m): 1,695 ft (517 m)
  • Landing distance from 50 ft (15 m): 1,695 ft (517 m)

See also

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Aircraft of comparable role, configuration, and era

References

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[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Piper PA-23

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from Grokipedia
The Piper PA-23 is an American twin-engine, low-wing, all-metal family developed by Company, initially introduced as the four-seat in 1954 as the company's first venture into multi-engine designs. It evolved into the more powerful and spacious Aztec variant in 1960, offering five- or six-seat configurations with enhanced load-carrying capabilities, making it popular for private, business, and utility operations. The PA-23 originated from Piper's acquisition of the Twin Stinson design in 1948, which was refined into the prototype that received FAA type certification on January 29, 1954. Early Apaches were powered by two 150-horsepower engines, with a maximum gross weight of 3,500 pounds, a cruise speed of about 157 knots, and a useful load approaching 1,500 pounds, emphasizing short-field performance and reliability for its era. By 1960, Piper upgraded the design to the Aztec with 250-horsepower engines, a swept vertical for improved stability, and a stretched , increasing gross weight to 5,200 pounds in later models and boosting cruise speeds to 178–200 knots while maintaining strong short-takeoff capabilities around 1,100–2,000 feet. Key variants include the original (PA-23-150/160), the intermediate Apache 235 (PA-23-235) with 235-horsepower engines from 1962 to 1965, and the Aztec series (PA-23-250) spanning models A through F from 1960 to 1982, with later iterations adding turbocharging, components, and a for better handling. Notable features across the line encompass a high-lift for heavy hauling, a roomy cabin accommodating up to six passengers plus , and retractable tricycle , though single-engine performance was modest at 180–240 feet per minute climb rate, prioritizing overall utility over speed. Fuel consumption ranged from 16 to 35 gallons per hour depending on power settings, with standard capacity of 144 usable gallons supporting ranges up to 1,000 nautical miles. Production totaled approximately 2,036 , 114 Apache 235s, and 5,500 through 1982, with military adaptations like the U.S. Navy's U-11A utility version. The PA-23 family remains in widespread use today for its durability, parts availability, and versatility in roles from to cargo hauling, though owners note ongoing maintenance needs for engines and corrosion-prone structures.

Development

Origins and early Apache

Following , sought to diversify its portfolio by entering the twin-engine light aircraft market, driven by increasing demand for reliable, multi-engine planes suitable for business and personal use. The company acquired the unfinished Twin Stinson design from Stinson Aircraft in 1948, a project originally intended as an all-metal, low-wing twin with retractable gear, and initiated a redesign to align with production capabilities and safety priorities. The resulting PA-23 Apache prototype incorporated key features such as all-metal construction and a tricycle landing gear configuration—influenced by aeronautical Fred Weick's pioneering work on stable designs like the Ercoupe—and accommodations for a pilot and five passengers, emphasizing ease of handling for less experienced pilots. Weick's prior NACA research on low-drag cowlings and safe flight characteristics informed such designs generally. Weick joined Piper in to lead later development efforts at the Vero Beach facility. The prototype achieved its first flight on March 2, 1952, under the designation PA-23 Twin-Stinson before being renamed , marking Piper's inaugural venture into twin-engine production. Extensive testing followed, focusing on stability, engine-out performance, and compliance under Civil Air Regulations Part 3. The received FAA type on January 29, 1954, enabling entry into production later that year. From 1954 to 1958, Piper produced 1,231 Apache units, primarily the PA-23-150 and subsequent PA-23-160 variants powered by 150- to 160-horsepower , establishing the model as a benchmark for affordable light twins before refinements led to the Aztec series. These early Apaches were marketed to corporate operators and flight schools, filling a niche for versatile with improved over single-engine contemporaries.

Aztec introduction and refinements

In 1959, Piper introduced the PA-23-250 Aztec as an upgraded evolution of the , featuring two Lycoming O-540-A1D five-cylinder engines each rated at 250 horsepower, a significant increase from the Apache's 150- to 235-horsepower powerplants. This power boost enhanced single-engine climb performance and overall speed, with the achieving a cruise speed of around 160 knots while maintaining the basic configuration. Initial refinements included a redesigned vertical with a swept fin and rudder for improved stability, along with aerodynamic tweaks to the cowlings. The Aztec was certified by the FAA in early following that validated the engine integration and structural modifications. The Aztec B, introduced in 1962, brought further refinements including a longer, more aerodynamic nose section that housed additional baggage space and improved forward visibility, while expanding the cabin to comfortably seat six passengers in a club-seating arrangement. Optional via Lycoming IO-540 engines was made available, enhancing efficiency and altitude performance without altering the core power output. Turbocharged engines were first offered as an option with this model. By late 1964, the Aztec C model standardized fuel-injected IO-540-C4B5 engines and incorporated upgraded packages, such as improved electrical systems and optional integration, alongside a gross weight increase to 5,200 pounds for better payload capacity. Certification testing for these IO-540 modifications focused on vibration analysis and fuel system reliability, ensuring compliance with FAA standards for high-altitude operations. Subsequent iterations from the Aztec D in 1971 through the E and F models continued refinements, with later models featuring refined propeller systems and optional adjustments for better handling. Production of the Aztec series spanned until , with over 5,000 units built across all variants, driven by demand for reliable multi-engine trainers and executive transports before market shifts toward more advanced composites and jets curtailed output.

Design

Airframe and systems

The Piper PA-23 series employs an all-metal airframe construction, utilizing aluminum over a framework of tubing in high-stress areas such as the and wing attachments, which enhances structural integrity and simplifies maintenance for both and Aztec variants. The consists of four primary sections—a tail cone, cabin enclosure, nose compartment, and reinforced tubular cage—finished with chromate primer and synthetic enamel for resistance. This design promotes durability in operations while allowing straightforward access for inspections and repairs. The wings adopt a low-wing configuration with a rectangular planform, a span of 37 feet 2.5 inches, and the USA 35-B modified sections, which provide stable lift characteristics suitable for the aircraft's multi-role use. Each wing features a stepped main spar, auxiliary front and rear spars, stringers, and ribs, with detachable tips for ease of handling; they attach to the via high-strength fittings that ensure a continuous load path across the structure. The all-metal control surfaces, including ailerons, flaps, , and elevators, are integrated into this framework without fabric covering, contributing to the airframe's overall weather resistance and longevity. Landing gear on the PA-23 is a retractable tricycle arrangement, hydraulically actuated by a single pump system, with air-oil oleo struts on all units to absorb shocks during rough-field landings. Main gear employs 600x6 wheels with 6-ply tires and disc brakes, while the nose gear uses a 600x6 4-ply tire and offers 30 degrees of steering authority; an emergency extension system combines a CO2 cartridge and manual hydraulic hand pump (requiring 30-50 strokes) for reliability in power loss scenarios. The cabin layout in the Aztec accommodates up to six passengers in a club seating arrangement, while the Apache has four or five seats, with steel tubular frames supporting foam cushions and adjustable reclining seats, fostering a spacious environment for business or family travel. In the Aztec, baggage capacity totals 300 pounds across forward and aft compartments (150 pounds each, with volumes of 21 and 26 cubic feet); the Apache offers about 200 pounds total, accessible via external doors and secured with straps for balanced loading. Amenities include armrests, reading lights, a glove compartment, and double-pane windows (with a storm window on the pilot's side) to enhance comfort and visibility. Avionics in the PA-23 series evolved from basic VFR/IFR configurations in production models, featuring provisions for up to four radio stacks, dual microphone/headset jacks, overhead speakers, and standard instruments like attitude indicators and navigation receivers. Refurbished commonly integrate modern systems, such as the GNS 430 WAAS GPS/NAV/COM and G500 glass displays, improving and compliance with current airspace requirements. Key safety systems include firewalls that isolate the twin engine nacelles from the cabin and fuel lines, minimizing fire propagation risks during integration of the powerplants. Dual fuel selectors allow independent management of wing tanks (with crossfeed capability) for engine-out operations, while additional features encompass an emergency exit window, stall warning horn, door-ajar indicator, and overheat protection in the cabin heater. These elements, combined with landing gear position lights and a warning horn, support safe handling in diverse conditions.

Engines and propulsion

The initial Apache variant of the Piper PA-23 was equipped with two Lycoming O-320-B1A flat-four air-cooled engines, each producing 150 horsepower at 2,700 RPM and featuring carbureted fuel induction for reliable operation in the normally aspirated configuration. These engines provided the twin-engine essential for the aircraft's multi-engine , emphasizing through balanced power delivery and straightforward routines typical of Lycoming's O-series . The initial Aztec was equipped with carbureted Lycoming O-540-A1B5 six-cylinder engines, each rated at 250 horsepower at 2,575 RPM. Starting with the 1965 Aztec C model, fuel-injected IO-540-C4B5 engines were used for improved efficiency and altitude performance. Starting in 1966 with the Aztec C model, turbocharged variants became available, initially with Rajay turbochargers on IO-540 engines and later with TIO-540-C1A engines maintaining the 250-horsepower output but enabling sustained power at higher altitudes, which enhanced the aircraft's suitability for operations in varied environmental conditions. This progression in propulsion options underscored the PA-23's evolution toward greater reliability and versatility in twin-engine applications. Both Apache and Aztec models utilized Hartzell constant-speed propellers with full-feathering capability, allowing pilots to feather the propeller on a failed engine to minimize drag and improve single-engine climb performance during emergency operations. The fuel system in the Aztec incorporated wing-mounted bladder tanks with a total usable capacity of 144 gallons; earlier Apache models had 72 gallons standard (108 optional), featuring balanced selectors and crossfeed valves to ensure even distribution to both engines and prevent yaw-inducing imbalances. These propulsion characteristics contributed to cruise speeds reaching up to 200 knots in turbocharged at optimal altitudes, with a standard service ceiling of 20,000 feet for normally aspirated models and up to 25,000 feet for turbo variants, providing adequate margin for en route weather avoidance and efficiency. emphasized engine-out procedures outlined in the pilot's operating , including immediate power reduction on the operating , propeller feathering, and airspeed control to achieve a positive single-engine climb rate, supported by the inherent reliability of as documented in FAA service bulletins.

Variants

Apache models

The Piper PA-23 Apache series introduced Piper's first twin-engine light aircraft, with the base model certified by the FAA in 1954 following its first flight in 1952. Powered by two Lycoming O-320-A1A engines each producing 150 horsepower, the PA-23-150 featured a maximum takeoff weight (MTOW) of 3,500 pounds and accommodated up to five occupants in a configuration emphasizing simplicity and affordability for general aviation use. Production of this initial variant began in March 1954, with the PA-23-150 and subsequent PA-23-160 totaling approximately 2,047 units, and the base model priced at around $32,500 in mid-1950s dollars. In 1957, Piper introduced the PA-23-160 as an updated variant, replacing the 150-horsepower engines with more powerful Lycoming O-320-B2A units rated at 160 horsepower each, which improved climb performance to about 1,000 feet per minute at . The MTOW increased to 3,800 pounds, allowing for greater useful load capacity while maintaining the core design. This model, produced through the late , addressed early criticisms of marginal single-engine performance in the base and became the predominant version before the transition to higher-powered Aztec derivatives. In 1962, Piper introduced the PA-23-235 as a more powerful Apache variant, powered by two Lycoming O-540-A2B carbureted engines each producing 235 horsepower, with a swept vertical tail for improved stability but retaining the shorter Apache . It featured an MTOW of 4,800 pounds, a cruise speed of about 170 knots, and was produced until 1965 with 118 units built. Special conversions for the Apache series included engine upgrade kits, such as those increasing power to 180 horsepower via modified O-360 installations, which boosted airspeed by 10 to 12 and improved overall efficiency. While no direct "Navajo" conversion kits were developed specifically for the smaller Apache airframe—those being reserved for the larger PA-31 series—aftermarket options like float installations enabled operations for international and remote markets. Export variants were adapted for global sales, incorporating regional and certification adjustments to meet demands in and during the 1950s.

Aztec models

The Piper PA-23-250 Aztec, certified on September 18, 1959, marked a significant upgrade from earlier models with the introduction of two 250-horsepower Lycoming O-540-A1B5 carbureted engines, a swept vertical , and an initial (MTOW) of 4,800 pounds, allowing for five seats and increased fuel capacity of 144 U.S. gallons. Production of the initial Aztec began in 1960, emphasizing enhanced performance for business and personal transport. In , the Aztec B variant was introduced, featuring fuel-injected Lycoming IO-540-C4B5 engines for improved efficiency and reliability, a longer nose section to accommodate a compartment and increase seating to six, along with an MTOW raised to 5,200 pounds. Optional turbocharging with AiResearch turbochargers became available from this model, enabling better high-altitude operations when paired with an oxygen system. The Aztec C, launched in late 1964, standardized and further refined with sleeker engine cowlings, while maintaining the 5,200-pound MTOW and offering turbo options that extended engine time between overhaul (TBO) to 2,000 hours. The subsequent Aztec D, produced from 1968 to 1970, incorporated minor interior and instrumentation updates without major structural changes. By 1971, the Aztec E introduced engine nacelles for easier maintenance and reduced weight, followed by the Aztec F as the final production model from 1972 to 1981, which added a flap-stabilator interconnect for better low-speed handling and compatibility with modern two-blade Hartzell propellers. The Turbo Aztec, certified as a distinct variant in 1966 with Lycoming TIO-540-C1A turbocharged s, featured a slightly lower MTOW of 4,995 pounds and a zero-fuel weight limit of 4,500 pounds to account for the added systems. Overall, approximately 5,400 were built across all variants through 1981, with the series concluding after two decades of production focused on iterative power and weight enhancements.
VariantIntroduction YearEnginesMTOW (lbs)Key Features
PA-23-250 Aztec A19592 × Lycoming O-540-A1B5 (250 hp, carbureted)4,800Swept , 5 seats, 144 gal
PA-23-250 Aztec B19622 × Lycoming IO-540-C4B5 (250 hp, )5,200Longer nose, 6 seats, optional turbo
PA-23-250 Aztec C19642 × Lycoming IO-540-C4B5 (250 hp)5,200Standard , sleeker cowlings, turbo option
PA-23-250 Aztec D19682 × Lycoming IO-540-C4B5 (250 hp)5,200Minor interior updates
PA-23-250 Aztec E19712 × Lycoming IO-540-C4B5 (250 hp)5,200 nacelles
PA-23-250 Aztec F19722 × Lycoming IO-540-C4B5 (250 hp)5,200Flap-stabilator interconnect, modern props
Turbo Aztec19662 × Lycoming TIO-540-C1A (250 hp, turbocharged)4,995High-altitude performance, oxygen system

Operational history

Civil operations

The Piper PA-23 series, encompassing both Apache and Aztec variants, has served as a cornerstone in civil since its debut in 1954, primarily fulfilling roles in personal transport for families and business executives seeking reliable multi-engine travel. Air taxi operators adopted it for short-haul passenger services, leveraging its capacity for four to six occupants and stable handling characteristics. In remote regions, the aircraft excelled in cargo hauling, where its short-field performance and rugged design supported operations on unprepared strips, particularly in areas like and the Australian . Market success stemmed from the PA-23's production run of approximately 7,650 units between 1954 and 1982, with 2,036 , 114 Apache 235s, and 5,500 built, establishing it as one of Piper's best-selling twins due to its affordability, ease of maintenance, and proven reliability in diverse environments. The model gained strong adoption in the United States for business and training flights, in for bush operations, and in for regional connectivity, where operators valued its ability to handle varying weather and terrain without excessive downtime. As of 2023, over 2,000 PA-23 aircraft remain active on the FAA registry, reflecting ongoing demand in programs for multi-engine ratings and in for utility missions. Owners continue to utilize upgraded models with modern for instrument approaches, underscoring the type's adaptability to contemporary needs. Economic viability has sustained its popularity, with variable operating costs averaging around $235 per hour, including fuel at 25-30 gallons per hour and routine maintenance, while annual premiums for light twins typically range from $2,500 to $3,500 depending on pilot experience and coverage limits. The PA-23's approval for single-pilot (IFR) operations under its original certification further cemented its role, enabling solo pilots to conduct all-weather flights efficiently.

Military service

The procured 20 examples of the Piper PA-23-250 Aztec in 1959 for utility and liaison duties, initially designating them UO-1 before redesignating them U-11A under the 1962 Tri-Service system. These aircraft featured standard modifications including radio equipment, oxygen systems, and propeller anti-icing to support naval operations. The U-11As served primarily in training and transport roles during the , with retirement occurring in the early 1970s as more advanced platforms became available. Several surviving examples are preserved in museums, including the in and the MAPS Air Museum in . Internationally, the PA-23 series saw adoption by numerous armed forces starting in the for light utility, training, and reconnaissance missions. The Brazilian Air Force operated the PA-23-250 Aztec under the local designation C-26 for general transport and support tasks. Similarly, the Spanish Air Force utilized the PA-23-250 Aztec E variant, with aircraft bearing serials such as E.19-2 and E.19-3, in utility roles at bases like Madrid-Cuatro Vientos. Other operators included the militaries of , , , , , , , , , , , , , and , where the type performed liaison and light transport functions often with minimal modifications beyond enhancements. Military service of the PA-23 peaked during the era for observer training and utility operations, particularly in and , though specific Vietnam War involvement remains undocumented. Many fleets were phased out by the 1980s and 1990s in favor of turbine-powered or offering greater speed and range, but select examples persisted in secondary roles into the . As of 2025, limited numbers remain active with smaller air forces for light transport, underscoring the type's enduring reliability in resource-constrained environments.

Incidents and accidents

Notable crashes

The development of the Piper PA-23 involved significant modifications to the following issues identified during initial prototype testing in the early , which prompted a redesign to improve reliability and handling characteristics before production certification. One early high-profile incident occurred on October 31, 1973, when a Piper PA-23-250 Aztec (N5141Y) crashed after the pilot was advised of icing conditions during a weather briefing but continued flight without wing equipment, leading to a loss of control; the aircraft was destroyed, and both occupants were fatally injured. This event highlighted vulnerabilities in non-equipped twins operating in adverse , contributing to NTSB recommendations for enhanced pilot training on icing avoidance. In the , engine failures contributed to several accidents, including a January 17, 2019, crash near , where a Piper PA-23-250 (N14372) impacted after a loss of control with suspected power loss, resulting in one fatality (the pilot); post-accident examination revealed no pre-impact mechanical failures, but the NTSB emphasized the challenges of managing engine-out scenarios in the type. Another incident on , 2010, involved a Piper PA-23-250 (N1526T) that crashed into the water off the shoreline near Alice Town, , after engine issues, killing both occupants; the aircraft clipped power lines, lost a wing, and spilled hot fuel, severely burning two bystanders on the beach. Recent events include a May 24, 2022, overrun at , involving a Piper PA-23-250 Aztec during a no-flap , where the pilot's high approach speed and failure to attain a proper point caused the to overrun the , veer off, and strike a , resulting in substantial damage and one injury; the NTSB cited pilot decision-making factors, with no evidence of brake failure. In 2024, a Piper PA-23-250 Aztec E (N555MH) ditched off , on September 12 due to fuel exhaustion en route from , resulting in two fatalities and four injuries among the six occupants; the AAIA investigation confirmed inadequate preflight fuel planning as the primary cause. In 2025, additional incidents occurred, including a fatal crash on October 17 near , involving N2345R with three fatalities, and a substantial damage event on September 6 near , with N4085P and no injuries. Common causes across PA-23 accidents include engine-out , where the aircraft's low single-engine climb rate (typically 100-240 feet per minute) exacerbates control difficulties, and in multi-engine operations, such as improper flap-gear lever management or inadequate response to power loss, as documented in NTSB analyses of light twin mishaps. Fuel system issues, particularly water contamination leading to power loss, have been recurrent, with the NTSB identifying 14 confirmed cases from 1975 to the late 1980s and suspecting involvement in approximately 40 additional PA-23 incidents, prompting FAA Airworthiness Directive 92-13-4 for improved fuel drainage procedures. As of 2024, the PA-23 series has recorded approximately 907 accidents with 1,304 associated fatalities, according to the Aviation Safety Network database; historical NTSB data for light twins like the PA-23 indicate a fatal accident rate of about 2.04 per 100,000 flight hours in the , though rates have improved to around 1.2 per 100,000 hours in recent decades.

Safety record analysis

The Piper PA-23 series, encompassing the Apache and Aztec variants, exhibits an overall accident rate for light twin-engine aircraft of approximately 7.46 incidents per 100,000 flight hours, with a fatal accident rate of 2.04 per 100,000 hours, based on (NTSB) data from the late 1970s that remains indicative of historical trends for similar piston twins. This rate is generally higher than that of comparable single-engine aircraft, which averaged around 5.0-6.0 accidents per 100,000 hours in the same period, though PA-23-specific data shows elevated risks due to its marginal single-engine performance and higher lethality (20-50% fatal in engine failure cases vs. under 10% for singles). Compared to modern twin-engine designs like the 58 or Piper Seneca V, which benefit from improved aerodynamics and power, the PA-23's accident profile is elevated, particularly in engine failure cases. Key safety challenges in the PA-23 stem from design and maintenance vulnerabilities in older models, including fuel system where accumulation in un-drained sumps has contributed to at least 14 confirmed power-loss accidents in Apaches from to the late , with suspicions in approximately 40 additional incidents across PA-23 variants per NTSB reviews. Propeller synchronization failures, while less prevalent, have occasionally led to asymmetric thrust issues exacerbating engine-out handling, compounded by the aircraft's low single-engine climb rate of 180-240 feet per minute, which demands precise pilot technique to avoid stalls. Safety enhancements have addressed these through (FAA) Airworthiness Directives (ADs), such as AD 78-02-03 (superseded in later years) mandating inspections and reinforcements for engine mounts on PA-23-250 models to prevent fatigue cracks, originally issued in the late with ongoing applicability into the . Additional ADs like 90-23-18 and 92-13-4 targeted drainage to mitigate contamination risks. Supplemental Type Certificates (STCs) enable modern upgrades, including G500 systems approved for Part 23 aircraft like the PA-23, providing integrated digital displays to reduce pilot workload and error. The PA-23's redundant twin-engine design contributes to relatively high survival rates in incidents, with approximately 50-80% of engine-out accidents non-fatal, attributed to the ability to maintain controlled flight despite power loss, though outcomes depend on altitude and pilot response. Contemporary safety for the PA-23 fleet has improved through retrofits such as (TCAS) and (WAAS)-enabled GPS, which enhance and navigation precision in twins, correlating with broader reductions in and approach accidents by up to 40% in equipped aircraft since 2000 per NTSB analyses of upgrades.

Specifications

General characteristics

The Piper PA-23-250 Aztec F is configured for a of one or two pilots and accommodates up to five passengers in its cabin. The measures 31 feet 3 inches in , has a of 37 feet 3 inches (wing area of 207 square feet), and stands 10 feet 4 inches in height. It features Hartzell HC-E2YR-2RBSF/F8465-7R propellers. It has a typical empty weight of 3,180 pounds, a of 5,200 pounds (useful load approximately 2,020 pounds), and a standard fuel capacity of 144 US gallons (140 usable). The airframe employs an all-aluminum alloy construction for the and wings, supplemented by tubing for engine mounts and select magnesium components in non-structural areas. No armament is standard on the civil model, though military variants such as the U-11 featured optional equipment provisions.

Performance

The Piper PA-23-250 Aztec F demonstrates solid flight for a twin-engine , with a maximum speed of 215 knots achieved at 22,000 feet under maximum power and standard atmospheric conditions. At 75% power, it maintains a cruise speed of 182 knots at 10,000 feet, providing efficient operation for typical cross-country missions while balancing speed and fuel economy. This cruise setting supports a range of 945 nautical miles with 45-minute reserves, corresponding to an endurance of approximately 5.2 hours with standard fuel load. The 's service ceiling reaches 19,000 feet, enabling operations in non-icing conditions at moderate altitudes. Initial is 1,400 feet per minute at , reflecting the contribution of its 250-horsepower Lycoming IO-540-C4B5 , while the single-engine climb rate stands at 225 feet per minute, sufficient for maintaining altitude following an under gross weight conditions. Short-field performance is a key strength, with a takeoff distance of 1,980 feet over a 50-foot obstacle and a landing ground roll of 951 feet, allowing access to smaller airfields when properly configured with full flaps and at maximum gross weight. Fuel consumption totals 30 gallons per hour at cruise power (15 gallons per engine), emphasizing the model's practical utility for multi-crew or family travel without excessive operating costs.

References

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