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PA-23 Apache/Aztec
PA-23 Aztec
Type	Twin-engined light piston utility
Manufacturer	Piper Aircraft
Maiden flight	1952
Introduction	1954
Primary user	United States Navy
Produced	1952-1981
Number built	6,976
Developed from	Twin Stinson

The Piper PA-23, named Apache and later Aztec, was an American twin-engined monoplane, the first twin-engine aircraft built by Piper Aircraft.

Originally to be named the "Twin-Stinson" and designed as a four-seater low-wing all-metal monoplane with a twin tail, the prototype first flew 2 March 1952. The prototype was then named the PA-21 to conform to Piper's numerical nomenclature[1] It was redesigned with a single vertical stabilizer and an all-metal rear fuselage and renamed to Apache 150 when it entered production in 1954; 1,231 were built. In 1958, the Apache 160 was produced by upgrading the engines to 160 hp (119 kW), and 816 were built before being superseded by the Apache 235, which went to 235 hp (175 kW) engines and swept tail surfaces (119 built).

Declining sales of the Apache prompted the redesign dubbed PA-23-250 Aztec, with 250 hp (186 kW) Lycoming. The first models were delivered with O-540 Lycoming carburetor engines. These first models came in a five-seat configuration which became available in 1959. 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.

Among other light twin-engined airplanes of its generation, the Aztec was known for its good load hauling, long endurance, stable handling, and respectable single-engine performance, at the cost of higher fuel consumption and a draggier (slower) airframe. Part of the drag was due to use of the same basic wing design (albeit with substantially different dimensions and construction) as the Piper Cub series of aircraft. The Piper Cub airfoil gave the Aztec superior short field operation characteristics at the price of lower performance at cruising speeds.

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

Contents 1 Variants 2 Military Operators 3 Specifications (model E, normally aspirated) 4 Related content

PA-23 Apache

Initial production version, 2047 built (including the Apache E, G and H).

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 0-320-B2B engines and minor changes.

PA-23-235 Apache 235

Aztec with 5 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 sub-variants)

PA-23-250 Aztec B

Aztec with longer nose for a baggage compartment, six-seats, new instrument panel and changes to systems.

PA-23-250 Aztec C

Aztec B with either IO-540-C4B5 engines or turbocharged TIO-540-C4B5 as an option, also modified engine nacelles and modified landing gear.

PA-23-250 Aztec D

Aztec B with revised instrument panel and controls.

PA-23-250 Aztec E

Aztec D with longer pointed nose and a single piece windshield.

PA-23-250 Aztec F

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.

 Argentina

 Bolivia

 Cameroon

 Colombia

 Costa Rica

 Madagascar

 Mexico

 Spain

• Spanish Air Force
  • Escaudrón 912
  • Escuadrilla de Enlace 905

 United States

• US Navy

 Venezuela

General characteristics

• Crew: one, pilot
• Capacity: 6 passengers (4 in the early models)
• Length: 31 ft 3 in (9.51 m)
• Wingspan: 37 ft 2 in (11.3 m)
• Height: 10 ft 4 in (3.14 m)
• Wing area: 208 ft² (19.3 m²)
• Empty weight: 3,300 lb (1500 kg)
• Max takeoff weight: 5,200 lb (2360 kg)
• Powerplant: 2× Lycoming O-540-C4B5 , 250 hp (186 kW) each

Performance

• Maximum speed: 210 mph (182 knots, 340 km/h)
• Range: 1,200 miles (1042 nm, 1,900 km)
• Service ceiling: 20,000 ft (6100 m)
• Rate of climb: 1,500 ft/min (460 m/min)
• Wing loading: 25 lb/ft² (120 kg/m²)
• Power/mass: 10 lb/hp (3.38 kg/kW)

Related development

Helio Twin Courier

Comparable aircraft

• Cessna 310
• Beech Baron
• Piper Seneca

Designation sequence

pre-1962

UO-1

post-1962

U-7 - U-8 - U-9 - U-10 - U-11 Aztec - U-16 - U-17

See also

v • d • e Piper aircraft models
Civilian	E-2 · F-2 · G-2 · H-2 · J-2 (Taylor) · J-2 (Piper) · J-3 · J-4 · J-5 · PA-6 · PA-7 · PA-8 · PA-11 · PA-12 · PA-14 · PA-15 · PA-16 · PA-17 · PA-18 · PA-20 · PA-22 · PA-23 · PA-24 · PA-25  · PA-28 · PA-30 · PA-31 · PA-31T · PA-32 · PA-32R · PA-34 · PA-36 · PA-38 · PA-39 · PA-40 · PA-42 · PA-44 · PA-46 · PA-60 · PiperJet
Military	AE · C-83 · HE · L-4 · L-14 · L-18 · L-21 · LNP · NE · O-59 · PA-48 · TG-8 · U-7

v • d • e Lists relating to aviation
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Military	Air forces · Aircraft weapons · Missiles · Unmanned aerial vehicles (UAVs) · Experimental aircraft
Notable incidents and accidents	Military aviation · Airliners · General aviation · Famous aviation-related deaths
Records	Flight airspeed record · Flight distance record · Flight altitude record · Flight endurance record · Most produced aircraft